From 674806b5356862fe9bde107d027f5ed5eab0b8b5 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Sun, 24 Jul 2022 13:11:52 +0100
Subject: [PATCH 01/14] feature: add module for BME280 sensor.

---
 Lib/Inc/BME280.h | 17 +++++++++++++++++
 Lib/Src/BME280.c | 12 ++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 Lib/Inc/BME280.h
 create mode 100644 Lib/Src/BME280.c

diff --git a/Lib/Inc/BME280.h b/Lib/Inc/BME280.h
new file mode 100644
index 00000000..1bde7816
--- /dev/null
+++ b/Lib/Inc/BME280.h
@@ -0,0 +1,17 @@
+/**
+ *@file BME280.h
+ *@brief This file contains the API functions for accessing BME280 sensor.
+ *
+ */
+
+/*
+ * BME280.h
+ *
+ *  Created on: 24 Jul 2022
+ *      Author: salavat.magazov
+ */
+
+#ifndef INC_BME280_H_
+#define INC_BME280_H_
+
+#endif /* INC_BME280_H_ */
diff --git a/Lib/Src/BME280.c b/Lib/Src/BME280.c
new file mode 100644
index 00000000..c95eb52a
--- /dev/null
+++ b/Lib/Src/BME280.c
@@ -0,0 +1,12 @@
+/**
+ *@file BME280.c
+ *@brief This file contains the BME280 sensor driver code.
+ *
+ */
+
+/*
+ * BME280.c
+ *
+ *  Created on: 24 Jul 2022
+ *      Author: salavat.magazov
+ */

From 1e3a824369aa880299b1e4ee3f0784205625f13e Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Sun, 24 Jul 2022 13:30:08 +0100
Subject: [PATCH 02/14] feature: transfer Sam's code unmodified to a new
 module.

---
 Lib/Inc/BME280.h |  12 +++
 Lib/Src/BME280.c | 221 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 233 insertions(+)

diff --git a/Lib/Inc/BME280.h b/Lib/Inc/BME280.h
index 1bde7816..6fe8f3b0 100644
--- a/Lib/Inc/BME280.h
+++ b/Lib/Inc/BME280.h
@@ -14,4 +14,16 @@
 #ifndef INC_BME280_H_
 #define INC_BME280_H_
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    // Function prototypes and all definitions that should be visible from
+    // outside the module go here.
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* INC_BME280_H_ */
diff --git a/Lib/Src/BME280.c b/Lib/Src/BME280.c
index c95eb52a..8c9f526b 100644
--- a/Lib/Src/BME280.c
+++ b/Lib/Src/BME280.c
@@ -10,3 +10,224 @@
  *  Created on: 24 Jul 2022
  *      Author: salavat.magazov
  */
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#include <string.h>
+#include "gpio.h"
+#include "spi.h"
+
+    const uint8_t ctrl_meas = 0b01110100;
+    const uint8_t ctrl_hum = 0b01110010;
+    const uint8_t config = 0b01110101;
+    const uint8_t status = 0b11110011;
+    const uint8_t hum_msb = 0b11111101;
+    const uint8_t temp_msb = 0b11111010;
+    const uint8_t dig_H1_addr = 0b10100001;
+    const uint8_t dig_H2_addr = 0b11100001;
+    const uint8_t dig_H3_addr = 0b11100011;
+    const uint8_t dig_H4_addr = 0b11100100;
+    const uint8_t dig_H5_addr = 0b11100101;
+    const uint8_t dig_H6_addr = 0b11100111;
+    const uint8_t dig_T1_addr = 0b10001000;
+    const uint8_t dig_T2_addr = 0b10001010;
+    const uint8_t dig_T3_addr = 0b10001100;
+
+    HAL_StatusTypeDef ret;
+    uint8_t hum_val[3];   // humidity raw value
+    uint8_t temp_val[3];  // temperature raw value
+    typedef int32_t BME280_S32_t;
+    typedef uint32_t BME280_U32_t;
+
+    BME280_S32_t t_fine, adc_T, adc_H;
+    uint8_t spi_buff[5];              // SPI buffer not for measurements
+    uint8_t hum_osrs = 0b00000001;    // enable humidity with x1 oversampling
+    uint8_t meas_val = 0b00100001;    // set forced mode and turn off press
+    uint8_t filter_off = 0b00000000;  // turn off filter
+    BME280_U32_t humidity;            // final humidity value
+    uint8_t digT1[2];
+    int8_t digT2[2], digT3[2], digH2[2];
+
+    unsigned short dig_T1;
+    short dig_T2, dig_T3, dig_H2, dig_H4, dig_H5, dig_H4_ls[2], dig_H5_ls[2];
+    unsigned char dig_H1, dig_H3, digH6;
+    char dig_H6;
+    memset(spi_buff, 0, sizeof(spi_buff));
+    // select mode 0
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
+
+    // write settings
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&ctrl_hum, 1, 100);
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&hum_osrs, 1, 100);
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&ctrl_meas, 1, 100);
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&meas_val, 1, 100);
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&config, 1, 100);
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&filter_off, 1, 100);
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
+
+    spi_buff[0] = 1;
+
+    // check status
+    while (spi_buff[0] & 0b00001000)
+    {  // bit masking need bit 3
+
+        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
+        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
+        HAL_SPI_Transmit(&hspi2, (uint8_t *)&status, 1, 100);
+        HAL_SPI_Receive(&hspi2, (uint8_t *)spi_buff, 1, 100);
+        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
+    }
+
+    // read hum data
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&hum_msb, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)hum_val, 2, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)hum_val, 2, 100);
+    }
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
+    adc_H = (hum_val[1] >> 8) | (hum_val[0]);
+
+    // read temp data
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&temp_msb, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)temp_val, 1, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)temp_val, 1, 100);
+    }
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
+
+    // correct temp data
+    adc_T = (temp_val[2] >> 24) | (temp_val[1] >> 21) | temp_val[0];
+
+    // read data
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_T1_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT1, 2, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT1, 2, 100);
+    }
+
+    dig_T1 = (digT1[1] << 8) | digT1[0];
+
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_T2_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT2, 2, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT2, 2, 100);
+    }
+
+    dig_T2 = (int)(digT2[1] << 8) | (int)digT2[0];
+
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_T3_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT3, 2, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT3, 2, 100);
+    }
+
+    dig_T3 = (int)((digT3[1] << 8) | digT3[0]);
+
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H1_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&dig_H1, 1, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&dig_H1, 1, 100);
+    }
+
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H2_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digH2, 2, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digH2, 2, 100);
+    }
+
+    dig_H2 = (int)((digH2[1] << 8) | digH2[0]);
+
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H3_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&dig_H3, 1, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&dig_H3, 1, 100);
+    }
+
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H4_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)dig_H4_ls, 2, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)dig_H4_ls, 2, 100);
+    }
+
+    dig_H4_ls[1] = dig_H4_ls[1] & 0b0000000000001111;
+    dig_H4 = (int)(dig_H4_ls[0] | dig_H4_ls[1]);
+
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H5_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)dig_H5_ls, 2, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)dig_H5_ls, 2, 100);
+    }
+
+    dig_H5_ls[0] = (dig_H5_ls[0] & 0b1111000000000000) >> 12;
+    dig_H5_ls[1] = dig_H5_ls[1] << 8;
+    dig_H5 = (int)(dig_H5_ls[1] | dig_H5_ls[0]);
+
+    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H6_addr, 1, 100);
+    ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&digH6, 1, 100);
+    while (ret != HAL_OK)
+    {
+        ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&digH6, 1, 100);
+    }
+
+    dig_H6 = (char)digH6;
+
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
+
+    // perform calculations
+    BME280_S32_t var1, var2;
+    var1 = ((((adc_T >> 3) - ((BME280_S32_t)dig_T1 << 1))) *
+            ((BME280_S32_t)dig_T2)) >>
+           11;
+
+    var2 = (((((adc_T >> 4) - ((BME280_S32_t)dig_T1)) *
+              ((adc_T >> 4) - ((BME280_S32_t)dig_T1))) >>
+             12) *
+            ((BME280_S32_t)dig_T3)) >>
+           14;
+    t_fine = var1 + var2;
+
+    BME280_S32_t v_x1_u32r;
+    v_x1_u32r = (t_fine - ((BME280_S32_t)76800));
+    v_x1_u32r = (((((adc_H << 14) - (((BME280_S32_t)dig_H4) << 20) -
+                    (((BME280_S32_t)dig_H5) * v_x1_u32r)) +
+                   ((BME280_S32_t)16384)) >>
+                  15) *
+                 (((((((v_x1_u32r * ((BME280_S32_t)dig_H6)) >> 10) *
+                      (((v_x1_u32r * ((BME280_S32_t)dig_H3)) >> 11) +
+                       ((BME280_S32_t)32768))) >>
+                     10) +
+                    ((BME280_S32_t)2097152)) *
+                       ((BME280_S32_t)dig_H2) +
+                   8192) >>
+                  14));
+    v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) *
+                               ((BME280_S32_t)dig_H1)) >>
+                              4));
+    v_x1_u32r = (v_x1_u32r < 0 ? 0 : v_x1_u32r);
+    v_x1_u32r = (v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r);
+
+    humidity = (BME280_U32_t)(v_x1_u32r >> 12);
+
+#ifdef __cplusplus
+}
+#endif

From 852b544cf8f14073be3bd022e41db6f81dc6bedd Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Mon, 25 Jul 2022 08:50:44 +0100
Subject: [PATCH 03/14] feature: add sensor initialisation method

---
 Lib/Inc/BME280.h    |  29 ------
 Lib/Inc/CBME280.h   |  84 ++++++++++++++++
 Lib/Src/BME280.c    | 233 --------------------------------------------
 Lib/Src/CBME280.cpp | 148 ++++++++++++++++++++++++++++
 4 files changed, 232 insertions(+), 262 deletions(-)
 delete mode 100644 Lib/Inc/BME280.h
 create mode 100644 Lib/Inc/CBME280.h
 delete mode 100644 Lib/Src/BME280.c
 create mode 100644 Lib/Src/CBME280.cpp

diff --git a/Lib/Inc/BME280.h b/Lib/Inc/BME280.h
deleted file mode 100644
index 6fe8f3b0..00000000
--- a/Lib/Inc/BME280.h
+++ /dev/null
@@ -1,29 +0,0 @@
-/**
- *@file BME280.h
- *@brief This file contains the API functions for accessing BME280 sensor.
- *
- */
-
-/*
- * BME280.h
- *
- *  Created on: 24 Jul 2022
- *      Author: salavat.magazov
- */
-
-#ifndef INC_BME280_H_
-#define INC_BME280_H_
-
-#ifdef __cplusplus
-extern "C"
-{
-#endif
-
-    // Function prototypes and all definitions that should be visible from
-    // outside the module go here.
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* INC_BME280_H_ */
diff --git a/Lib/Inc/CBME280.h b/Lib/Inc/CBME280.h
new file mode 100644
index 00000000..438905ee
--- /dev/null
+++ b/Lib/Inc/CBME280.h
@@ -0,0 +1,84 @@
+/**
+ *@file CBME280.h
+ *
+ */
+
+/*
+ * CBME280.h
+ *
+ *  Created on: 24 Jul 2022
+ *      Author: salavat.magazov
+ */
+
+#ifndef CBME280_H_
+#define CBME280_H_
+
+#include "CGpioWrapper.h"
+#include "gpio.h"
+#include "spi.h"
+
+#define T_CALIBRATION_SIZE 3
+#define P_CALIBRATION_SIZE 9
+#define H_CALIBRATION_SIZE 6
+
+class CBME280
+{
+    enum REGISTER_MAP
+    {
+        /* Calibration registers. */
+        DIG_T1 = 0x88,
+        DIG_T2 = 0x8A,
+        DIG_T3 = 0x8C,
+        DIG_P1 = 0x8E,
+        DIG_P2 = 0x90,
+        DIG_P3 = 0x92,
+        DIG_P4 = 0x94,
+        DIG_P5 = 0x96,
+        DIG_P6 = 0x98,
+        DIG_P7 = 0x9A,
+        DIG_P8 = 0x9C,
+        DIG_P9 = 0x9E,
+        DIG_H1 = 0xA1,
+        DIG_H2 = 0xE1,
+        DIG_H3 = 0xE3,
+        DIG_H4 = 0xE4,
+        DIG_H5 = 0xE5,
+        /* Sensor data registers. */
+        ID = 0xD0,
+        RESET = 0xE0,
+        CTRL_HUM = 0xF2,
+        STATUS = 0xF3,
+        CTRL_MEAS = 0xF4,
+        CONFIG = 0xF5,
+        PRESS_MSB = 0xF7,
+        PRESS_LSB = 0xF8,
+        PRESS_XLSB = 0xF9,
+        TEMP_MSB = 0xFA,
+        TEMP_LSB = 0xFB,
+        TEMP_XLSB = 0xFC,
+        HUM_MSB = 0xFD,
+        HUM_LSB = 0xFE
+    };
+
+public:
+    CBME280(SPI_HandleTypeDef *p_spi,
+            GPIO_TypeDef *p_slave_select_port,
+            uint16_t slave_select_pin);
+    virtual ~CBME280();
+
+    bool init();
+
+private:
+    void calibrateSensor(uint8_t const *const p_calibration_data);
+
+    SPI_HandleTypeDef *mp_spi;
+    CGpioWrapper m_slave_select;
+
+    bool mb_initialised;
+
+    uint16_t m_temperature_calibration[T_CALIBRATION_SIZE];
+    uint16_t m_pressure_calibration[P_CALIBRATION_SIZE];
+    uint16_t m_humidity_calibration[H_CALIBRATION_SIZE];
+};
+
+#endif /* CBME280_H_ */
diff --git a/Lib/Src/BME280.c b/Lib/Src/BME280.c
deleted file mode 100644
index 8c9f526b..00000000
--- a/Lib/Src/BME280.c
+++ /dev/null
@@ -1,233 +0,0 @@
-/**
- *@file BME280.c
- *@brief This file contains the BME280 sensor driver code.
- *
- */
-
-/*
- * BME280.c
- *
- *  Created on: 24 Jul 2022
- *      Author: salavat.magazov
- */
-
-#ifdef __cplusplus
-extern "C"
-{
-#endif
-
-#include <string.h>
-#include "gpio.h"
-#include "spi.h"
-
-    const uint8_t ctrl_meas = 0b01110100;
-    const uint8_t ctrl_hum = 0b01110010;
-    const uint8_t config = 0b01110101;
-    const uint8_t status = 0b11110011;
-    const uint8_t hum_msb = 0b11111101;
-    const uint8_t temp_msb = 0b11111010;
-    const uint8_t dig_H1_addr = 0b10100001;
-    const uint8_t dig_H2_addr = 0b11100001;
-    const uint8_t dig_H3_addr = 0b11100011;
-    const uint8_t dig_H4_addr = 0b11100100;
-    const uint8_t dig_H5_addr = 0b11100101;
-    const uint8_t dig_H6_addr = 0b11100111;
-    const uint8_t dig_T1_addr = 0b10001000;
-    const uint8_t dig_T2_addr = 0b10001010;
-    const uint8_t dig_T3_addr = 0b10001100;
-
-    HAL_StatusTypeDef ret;
-    uint8_t hum_val[3];   // humidity raw value
-    uint8_t temp_val[3];  // temperature raw value
-    typedef int32_t BME280_S32_t;
-    typedef uint32_t BME280_U32_t;
-
-    BME280_S32_t t_fine, adc_T, adc_H;
-    uint8_t spi_buff[5];              // SPI buffer not for measurements
-    uint8_t hum_osrs = 0b00000001;    // enable humidity with x1 oversampling
-    uint8_t meas_val = 0b00100001;    // set forced mode and turn off press
-    uint8_t filter_off = 0b00000000;  // turn off filter
-    BME280_U32_t humidity;            // final humidity value
-    uint8_t digT1[2];
-    int8_t digT2[2], digT3[2], digH2[2];
-
-    unsigned short dig_T1;
-    short dig_T2, dig_T3, dig_H2, dig_H4, dig_H5, dig_H4_ls[2], dig_H5_ls[2];
-    unsigned char dig_H1, dig_H3, digH6;
-    char dig_H6;
-    memset(spi_buff, 0, sizeof(spi_buff));
-    // select mode 0
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
-
-    // write settings
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&ctrl_hum, 1, 100);
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&hum_osrs, 1, 100);
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&ctrl_meas, 1, 100);
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&meas_val, 1, 100);
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&config, 1, 100);
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&filter_off, 1, 100);
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
-
-    spi_buff[0] = 1;
-
-    // check status
-    while (spi_buff[0] & 0b00001000)
-    {  // bit masking need bit 3
-
-        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
-        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
-        HAL_SPI_Transmit(&hspi2, (uint8_t *)&status, 1, 100);
-        HAL_SPI_Receive(&hspi2, (uint8_t *)spi_buff, 1, 100);
-        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
-    }
-
-    // read hum data
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&hum_msb, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)hum_val, 2, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)hum_val, 2, 100);
-    }
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
-    adc_H = (hum_val[1] >> 8) | (hum_val[0]);
-
-    // read temp data
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&temp_msb, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)temp_val, 1, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)temp_val, 1, 100);
-    }
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
-
-    // correct temp data
-    adc_T = (temp_val[2] >> 24) | (temp_val[1] >> 21) | temp_val[0];
-
-    // read data
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_RESET);
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_10, GPIO_PIN_SET);
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_T1_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT1, 2, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT1, 2, 100);
-    }
-
-    dig_T1 = (digT1[1] << 8) | digT1[0];
-
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_T2_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT2, 2, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT2, 2, 100);
-    }
-
-    dig_T2 = (int)(digT2[1] << 8) | (int)digT2[0];
-
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_T3_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT3, 2, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digT3, 2, 100);
-    }
-
-    dig_T3 = (int)((digT3[1] << 8) | digT3[0]);
-
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H1_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&dig_H1, 1, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&dig_H1, 1, 100);
-    }
-
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H2_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digH2, 2, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)digH2, 2, 100);
-    }
-
-    dig_H2 = (int)((digH2[1] << 8) | digH2[0]);
-
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H3_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&dig_H3, 1, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&dig_H3, 1, 100);
-    }
-
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H4_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)dig_H4_ls, 2, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)dig_H4_ls, 2, 100);
-    }
-
-    dig_H4_ls[1] = dig_H4_ls[1] & 0b0000000000001111;
-    dig_H4 = (int)(dig_H4_ls[0] | dig_H4_ls[1]);
-
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H5_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (uint8_t *)dig_H5_ls, 2, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (uint8_t *)dig_H5_ls, 2, 100);
-    }
-
-    dig_H5_ls[0] = (dig_H5_ls[0] & 0b1111000000000000) >> 12;
-    dig_H5_ls[1] = dig_H5_ls[1] << 8;
-    dig_H5 = (int)(dig_H5_ls[1] | dig_H5_ls[0]);
-
-    HAL_SPI_Transmit(&hspi2, (uint8_t *)&dig_H6_addr, 1, 100);
-    ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&digH6, 1, 100);
-    while (ret != HAL_OK)
-    {
-        ret = HAL_SPI_Receive(&hspi2, (unsigned char *)&digH6, 1, 100);
-    }
-
-    dig_H6 = (char)digH6;
-
-    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_12, GPIO_PIN_SET);
-
-    // perform calculations
-    BME280_S32_t var1, var2;
-    var1 = ((((adc_T >> 3) - ((BME280_S32_t)dig_T1 << 1))) *
-            ((BME280_S32_t)dig_T2)) >>
-           11;
-
-    var2 = (((((adc_T >> 4) - ((BME280_S32_t)dig_T1)) *
-              ((adc_T >> 4) - ((BME280_S32_t)dig_T1))) >>
-             12) *
-            ((BME280_S32_t)dig_T3)) >>
-           14;
-    t_fine = var1 + var2;
-
-    BME280_S32_t v_x1_u32r;
-    v_x1_u32r = (t_fine - ((BME280_S32_t)76800));
-    v_x1_u32r = (((((adc_H << 14) - (((BME280_S32_t)dig_H4) << 20) -
-                    (((BME280_S32_t)dig_H5) * v_x1_u32r)) +
-                   ((BME280_S32_t)16384)) >>
-                  15) *
-                 (((((((v_x1_u32r * ((BME280_S32_t)dig_H6)) >> 10) *
-                      (((v_x1_u32r * ((BME280_S32_t)dig_H3)) >> 11) +
-                       ((BME280_S32_t)32768))) >>
-                     10) +
-                    ((BME280_S32_t)2097152)) *
-                       ((BME280_S32_t)dig_H2) +
-                   8192) >>
-                  14));
-    v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) *
-                               ((BME280_S32_t)dig_H1)) >>
-                              4));
-    v_x1_u32r = (v_x1_u32r < 0 ? 0 : v_x1_u32r);
-    v_x1_u32r = (v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r);
-
-    humidity = (BME280_U32_t)(v_x1_u32r >> 12);
-
-#ifdef __cplusplus
-}
-#endif
diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
new file mode 100644
index 00000000..bf7e6a9f
--- /dev/null
+++ b/Lib/Src/CBME280.cpp
@@ -0,0 +1,148 @@
+/**
+ *@file CBME280.cpp
+ *
+ */
+
+/*
+ * BME280.cpp
+ *
+ *  Created on: 24 Jul 2022
+ *      Author: salavat.magazov
+ */
+
+#include <CBME280.h>
+
+#define BME280_ID             0x60
+#define BMP280_ID             0x58
+#define SOFT_RESET            0xB6
+#define SPI_WRITE_MASK        0x80
+#define ID_PACKET_SIZE        2
+#define CALIB1_PACKET_SIZE    24
+#define CALIB2_PACKET_SIZE    1
+#define CALIB3_PACKET_SIZE    8
+#define SPI_TIMEOUT_MS        100
+#define SENSOR_RESET_DELAY_MS 9
+
+#define CONCAT_BYTES(msb, lsb) (((uint16_t)msb << 8) | (uint16_t)lsb)
+
+#define HIGH true
+#define LOW  false
+
+CBME280::CBME280(SPI_HandleTypeDef *p_spi,
+                 GPIO_TypeDef *p_slave_select_port,
+                 uint16_t slave_select_pin)
+    : mp_spi(p_spi),
+      m_slave_select(p_slave_select_port, slave_select_pin),
+      mb_initialised(false)
+{
+    if (mp_spi == nullptr)
+    {
+        Error_Handler();
+    }
+    m_slave_select.set(true);
+}
+
+CBME280::~CBME280()
+{
+    // TODO Auto-generated destructor stub
+}
+
+bool CBME280::init()
+{
+    /* TODO:
+     * 1. Check SPI works.
+     * 2. Read chip ID to verify comms to sensor works.
+     * 3. Read calibration values and store in appropriate places.
+     */
+    /* This communication via SPI is going to be done without interrupts.*/
+    // TODO: how do we ensure SPI is available? Perhaps need a wrapper around
+    // SPI with a mutex.
+    if (HAL_SPI_GetState(mp_spi) != HAL_SPI_STATE_READY)
+    {
+        Error_Handler();
+    }
+    uint8_t register_address;
+    /* Soft reset. */
+    register_address = RESET;
+    m_slave_select.set(false);
+    HAL_SPI_Transmit(mp_spi, &register_address, 1, SPI_TIMEOUT_MS);
+    m_slave_select.set(true);
+    HAL_Delay(SENSOR_RESET_DELAY_MS);
+    /* Read sensor ID to see if it is responding to comms. */
+    register_address = ID;
+    uint8_t id_register[ID_PACKET_SIZE];
+    m_slave_select.set(LOW);
+    HAL_SPI_TransmitReceive(mp_spi,
+                            &register_address,
+                            id_register,
+                            ID_PACKET_SIZE,
+                            SPI_TIMEOUT_MS);
+    m_slave_select.set(HIGH);
+    if ((id_register[1] != BME280_ID) && (id_register[1] != BMP280_ID))
+    {
+        return false;
+    }
+    /* Read sensor calibration data. */
+    register_address = DIG_T1;
+    uint8_t calibration_register[CALIB1_PACKET_SIZE +
+                                 CALIB2_PACKET_SIZE * CALIB3_PACKET_SIZE];
+    m_slave_select.set(LOW);
+    HAL_SPI_TransmitReceive(mp_spi,
+                            &register_address,
+                            calibration_register,
+                            CALIB1_PACKET_SIZE,
+                            SPI_TIMEOUT_MS);
+    m_slave_select.set(HIGH);
+    register_address = DIG_H1;
+    m_slave_select.set(LOW);
+    HAL_SPI_TransmitReceive(mp_spi,
+                            &register_address,
+                            &(calibration_register[CALIB1_PACKET_SIZE - 1]),
+                            CALIB2_PACKET_SIZE,
+                            SPI_TIMEOUT_MS);
+    m_slave_select.set(HIGH);
+    register_address = DIG_H2;
+    m_slave_select.set(LOW);
+    HAL_SPI_TransmitReceive(mp_spi,
+                            &register_address,
+                            &(calibration_register[CALIB1_PACKET_SIZE]),
+                            CALIB2_PACKET_SIZE,
+                            SPI_TIMEOUT_MS);
+    m_slave_select.set(HIGH);
+    calibrateSensor(calibration_register);
+    mb_initialised = true;
+    return true;
+}
+
+void CBME280::calibrateSensor(uint8_t const *const p_calibration_data)
+{
+    uint8_t const *p_runner = p_calibration_data;
+    for (int i = 0; i < T_CALIBRATION_SIZE; i++)
+    {
+        m_temperature_calibration[i] = *p_runner;
+        m_temperature_calibration[i] |= *(++p_runner) << 8;
+        ++p_runner;
+    }
+    for (int i = 0; i < P_CALIBRATION_SIZE; i++)
+    {
+        m_pressure_calibration[i] = *p_runner;
+        m_pressure_calibration[i] |= *(++p_runner) << 8;
+        ++p_runner;
+    }
+    /* Humidity calibration data is spread around and is stored in a weird
+     * convoluted way. See the manual. This recovery was copied with
+     * modifications from the Bosch github repository.
+     * https://github.com/BoschSensortec/BME280_driver */
+    /* I am certain the engineer at Bosch who came up with this had management
+     * breathing down their neck. One day they stopped caring and made this
+     * monstrocity.*/
+    m_humidity_calibration[0] = p_calibration_data[25];
+    m_humidity_calibration[1] =
+        (p_calibration_data[27] << 8) + p_calibration_data[26];
+    m_humidity_calibration[2] = p_calibration_data[28];
+    m_humidity_calibration[3] =
+        (p_calibration_data[29] << 4) + (p_calibration_data[30] & 0x0F);
+    m_humidity_calibration[4] =
+        (p_calibration_data[31] << 4) + (p_calibration_data[30] >> 4);
+    m_humidity_calibration[5] = p_calibration_data[32];
+}

From 7c55e7f50d4e293237d3fb72da60a2d17b5b2a68 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Mon, 25 Jul 2022 09:16:09 +0100
Subject: [PATCH 04/14] docs: add doxygen headers to methods. feature: add
 sensor data access methods.

---
 Lib/Inc/CBME280.h   | 39 +++++++++++++++++++++++++++++++++++++++
 Lib/Src/CBME280.cpp | 19 +++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/Lib/Inc/CBME280.h b/Lib/Inc/CBME280.h
index 438905ee..c4e5fa1e 100644
--- a/Lib/Inc/CBME280.h
+++ b/Lib/Inc/CBME280.h
@@ -68,8 +68,39 @@ class CBME280
 
     bool init();
 
+    /**
+     * @brief Access processed temperature data.
+     *
+     * @return Temperature in degrees Celsius.
+     */
+    float getTemperature() const
+    {
+        return m_temperature;
+    };
+
+    /**
+     * @brief Access processed pressure data.
+     *
+     * @return Pressure in Pascals.
+     */
+    float getPressure() const
+    {
+        return m_pressure;
+    };
+
+    /**
+     * @brief Access processed humidity data.
+     *
+     * @return Humidity in %RH.
+     */
+    float getHumidity() const
+    {
+        return m_humidity;
+    };
+
 private:
     void calibrateSensor(uint8_t const *const p_calibration_data);
+    void convertRawData(uint8_t const *const p_raw_adc_data);
 
     SPI_HandleTypeDef *mp_spi;
     CGpioWrapper m_slave_select;
@@ -79,6 +110,14 @@ class CBME280
     uint16_t m_temperature_calibration[T_CALIBRATION_SIZE];
     uint16_t m_pressure_calibration[P_CALIBRATION_SIZE];
     uint16_t m_humidity_calibration[H_CALIBRATION_SIZE];
+
+    uint32_t m_raw_temperature_data;
+    uint32_t m_raw_pressure_data;
+    uint32_t m_raw_humidity_data;
+
+    float m_temperature;
+    float m_pressure;
+    float m_humidity;
 };
 
 #endif /* CBME280_H_ */
diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index bf7e6a9f..bcecb682 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -28,6 +28,13 @@
 #define HIGH true
 #define LOW  false
 
+/**
+ * @brief Construct a sensor driver class instance.
+ *
+ * @param p_spi Pointer to HAL handler for SPI channel.
+ * @param p_slave_select_port Pointer to GPIO port for SS pin.
+ * @param slave_select_pin Mask of the SS pin.
+ */
 CBME280::CBME280(SPI_HandleTypeDef *p_spi,
                  GPIO_TypeDef *p_slave_select_port,
                  uint16_t slave_select_pin)
@@ -47,6 +54,12 @@ CBME280::~CBME280()
     // TODO Auto-generated destructor stub
 }
 
+/**
+ * @brief Initialise the sensor. This must be successfully completed before
+ * sensor can be accessed for data.
+ *
+ * @return True if initialisation is successful, false otherwise.
+ */
 bool CBME280::init()
 {
     /* TODO:
@@ -114,6 +127,12 @@ bool CBME280::init()
     return true;
 }
 
+/**
+ * @brief Convert raw data from the sensor registers into usable calibration
+ * values.
+ *
+ * @param p_calibration_data Pointer to raw data stream of 33 8-bit values.
+ */
 void CBME280::calibrateSensor(uint8_t const *const p_calibration_data)
 {
     uint8_t const *p_runner = p_calibration_data;

From 478051074e039dae98e5fb2d6612a0172f2ecaf1 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Mon, 25 Jul 2022 10:22:59 +0100
Subject: [PATCH 05/14] feature: add conversion of raw data stream into raw
 structured data.

---
 Lib/Src/CBME280.cpp | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index bcecb682..735327d5 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -165,3 +165,28 @@ void CBME280::calibrateSensor(uint8_t const *const p_calibration_data)
         (p_calibration_data[31] << 4) + (p_calibration_data[30] >> 4);
     m_humidity_calibration[5] = p_calibration_data[32];
 }
+
+/**
+ * @brief Convert raw data from sensor registers into corresponding unprocessed
+ * sensor values.
+ *
+ * @param p_raw_adc_data Pointer to raw data stream of 8 8-bit values.
+ */
+void CBME280::convertRawData(uint8_t const *const p_raw_adc_data)
+{
+    m_raw_pressure_data = p_raw_adc_data[0];
+    m_raw_pressure_data = m_raw_pressure_data << 8;
+    m_raw_pressure_data += p_raw_adc_data[1];
+    m_raw_pressure_data = m_raw_pressure_data << 4;
+    m_raw_pressure_data += p_raw_adc_data[2] >> 4;
+
+    m_raw_temperature_data = p_raw_adc_data[0];
+    m_raw_temperature_data = m_raw_temperature_data << 8;
+    m_raw_temperature_data += p_raw_adc_data[1];
+    m_raw_temperature_data = m_raw_temperature_data << 4;
+    m_raw_temperature_data += p_raw_adc_data[2] >> 4;
+
+    m_raw_humidity_data = p_raw_adc_data[6];
+    m_raw_humidity_data = m_raw_humidity_data << 8;
+    m_raw_humidity_data += p_raw_adc_data[7];
+}

From 59dfe1f2e8449c2b89c046ee64f4f069d3631627 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Mon, 25 Jul 2022 11:18:00 +0100
Subject: [PATCH 06/14] feature: add basic state machine to run sensor.

---
 Lib/Inc/CBME280.h   | 15 +++++++--
 Lib/Src/CBME280.cpp | 80 +++++++++++++++++++++++++++++++++++++--------
 2 files changed, 80 insertions(+), 15 deletions(-)

diff --git a/Lib/Inc/CBME280.h b/Lib/Inc/CBME280.h
index c4e5fa1e..4ce43578 100644
--- a/Lib/Inc/CBME280.h
+++ b/Lib/Inc/CBME280.h
@@ -20,6 +20,7 @@
 #define T_CALIBRATION_SIZE 3
 #define P_CALIBRATION_SIZE 9
 #define H_CALIBRATION_SIZE 6
+#define RAW_ADC_DATA_SIZE  8
 
 class CBME280
 {
@@ -67,6 +68,7 @@ class CBME280
     virtual ~CBME280();
 
     bool init();
+    bool run();
 
     /**
      * @brief Access processed temperature data.
@@ -100,17 +102,26 @@ class CBME280
 
 private:
     void calibrateSensor(uint8_t const *const p_calibration_data);
-    void convertRawData(uint8_t const *const p_raw_adc_data);
+    void convertRawData();
+    bool startMeasument();
+    void applyCalibration();
 
     SPI_HandleTypeDef *mp_spi;
     CGpioWrapper m_slave_select;
 
-    bool mb_initialised;
+    enum STATES
+    {
+        INIT_PENDING = 0,
+        READY,
+        MEASURING,
+        NEW_DATA
+    } m_state;
 
     uint16_t m_temperature_calibration[T_CALIBRATION_SIZE];
     uint16_t m_pressure_calibration[P_CALIBRATION_SIZE];
     uint16_t m_humidity_calibration[H_CALIBRATION_SIZE];
 
+    uint8_t m_raw_adc_data[RAW_ADC_DATA_SIZE];
     uint32_t m_raw_temperature_data;
     uint32_t m_raw_pressure_data;
     uint32_t m_raw_humidity_data;
diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index 735327d5..a4dadb0b 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -40,7 +40,7 @@ CBME280::CBME280(SPI_HandleTypeDef *p_spi,
                  uint16_t slave_select_pin)
     : mp_spi(p_spi),
       m_slave_select(p_slave_select_port, slave_select_pin),
-      mb_initialised(false)
+      m_state(INIT_PENDING)
 {
     if (mp_spi == nullptr)
     {
@@ -63,7 +63,7 @@ CBME280::~CBME280()
 bool CBME280::init()
 {
     /* TODO:
-     * 1. Check SPI works.
+     * 1. Check SPI available.
      * 2. Read chip ID to verify comms to sensor works.
      * 3. Read calibration values and store in appropriate places.
      */
@@ -72,7 +72,7 @@ bool CBME280::init()
     // SPI with a mutex.
     if (HAL_SPI_GetState(mp_spi) != HAL_SPI_STATE_READY)
     {
-        Error_Handler();
+        return false;
     }
     uint8_t register_address;
     /* Soft reset. */
@@ -123,10 +123,43 @@ bool CBME280::init()
                             SPI_TIMEOUT_MS);
     m_slave_select.set(HIGH);
     calibrateSensor(calibration_register);
-    mb_initialised = true;
     return true;
 }
 
+bool CBME280::run()
+{
+    bool b_new_data = false;
+    switch (m_state)
+    {
+        case INIT_PENDING:
+            if (init())
+            {
+                m_state = READY;
+            }
+            break;
+        case READY:
+            // TODO: perhaps need to have some sort of timeout here to only run
+            // this at regular intervals.
+            if (startMeasument())
+            {
+                m_state = MEASURING;
+            }
+            break;
+        case MEASURING:
+            // N.B. This state is a wait-state to allow class to know when it is
+            // busy waiting for SPI interrupt to fire.
+            break;
+        case NEW_DATA:
+            convertRawData();
+            applyCalibration();
+            b_new_data = true;
+            break;
+        default:
+            Error_Handler();
+    }
+    return b_new_data;
+}
+
 /**
  * @brief Convert raw data from the sensor registers into usable calibration
  * values.
@@ -172,21 +205,42 @@ void CBME280::calibrateSensor(uint8_t const *const p_calibration_data)
  *
  * @param p_raw_adc_data Pointer to raw data stream of 8 8-bit values.
  */
-void CBME280::convertRawData(uint8_t const *const p_raw_adc_data)
+void CBME280::convertRawData()
 {
-    m_raw_pressure_data = p_raw_adc_data[0];
+    m_raw_pressure_data = m_raw_adc_data[0];
     m_raw_pressure_data = m_raw_pressure_data << 8;
-    m_raw_pressure_data += p_raw_adc_data[1];
+    m_raw_pressure_data += m_raw_adc_data[1];
     m_raw_pressure_data = m_raw_pressure_data << 4;
-    m_raw_pressure_data += p_raw_adc_data[2] >> 4;
+    m_raw_pressure_data += m_raw_adc_data[2] >> 4;
 
-    m_raw_temperature_data = p_raw_adc_data[0];
+    m_raw_temperature_data = m_raw_adc_data[0];
     m_raw_temperature_data = m_raw_temperature_data << 8;
-    m_raw_temperature_data += p_raw_adc_data[1];
+    m_raw_temperature_data += m_raw_adc_data[1];
     m_raw_temperature_data = m_raw_temperature_data << 4;
-    m_raw_temperature_data += p_raw_adc_data[2] >> 4;
+    m_raw_temperature_data += m_raw_adc_data[2] >> 4;
 
-    m_raw_humidity_data = p_raw_adc_data[6];
+    m_raw_humidity_data = m_raw_adc_data[6];
     m_raw_humidity_data = m_raw_humidity_data << 8;
-    m_raw_humidity_data += p_raw_adc_data[7];
+    m_raw_humidity_data += m_raw_adc_data[7];
 }
+
+/**
+ * @brief Initiate measurement process.
+ *
+ * @return True if measurement started successfully.
+ */
+bool CBME280::startMeasument()
+{
+    if (HAL_SPI_GetState(mp_spi) != HAL_SPI_STATE_READY)
+    {
+        return false;
+    }
+
+    return true;
+}
+
+/**
+ * @brief Apply calibration to raw data.
+ *
+ */
+void CBME280::applyCalibration() {}

From 65d9806c8793c7cc2e3185ee7a214e9798c88e96 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Mon, 25 Jul 2022 12:07:23 +0100
Subject: [PATCH 07/14] wip

---
 Lib/Inc/CBME280.h   | 10 +++++++++-
 Lib/Src/CBME280.cpp | 22 ++++++++++++++++++++--
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/Lib/Inc/CBME280.h b/Lib/Inc/CBME280.h
index 4ce43578..954c6505 100644
--- a/Lib/Inc/CBME280.h
+++ b/Lib/Inc/CBME280.h
@@ -21,6 +21,7 @@
 #define P_CALIBRATION_SIZE 9
 #define H_CALIBRATION_SIZE 6
 #define RAW_ADC_DATA_SIZE  8
+#define MAX_SENSORS 2
 
 class CBME280
 {
@@ -100,10 +101,15 @@ class CBME280
         return m_humidity;
     };
 
+    bool isMeasuring() const
+    {
+        return m_state == MEASURING;
+    }
+
 private:
     void calibrateSensor(uint8_t const *const p_calibration_data);
     void convertRawData();
-    bool startMeasument();
+    bool startMeasurement();
     void applyCalibration();
 
     SPI_HandleTypeDef *mp_spi;
@@ -117,6 +123,8 @@ class CBME280
         NEW_DATA
     } m_state;
 
+    static CBME280* sp_sensors[]
+
     uint16_t m_temperature_calibration[T_CALIBRATION_SIZE];
     uint16_t m_pressure_calibration[P_CALIBRATION_SIZE];
     uint16_t m_humidity_calibration[H_CALIBRATION_SIZE];
diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index a4dadb0b..2ac42259 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -140,7 +140,7 @@ bool CBME280::run()
         case READY:
             // TODO: perhaps need to have some sort of timeout here to only run
             // this at regular intervals.
-            if (startMeasument())
+            if (startMeasurement())
             {
                 m_state = MEASURING;
             }
@@ -229,12 +229,24 @@ void CBME280::convertRawData()
  *
  * @return True if measurement started successfully.
  */
-bool CBME280::startMeasument()
+bool CBME280::startMeasurement()
 {
     if (HAL_SPI_GetState(mp_spi) != HAL_SPI_STATE_READY)
     {
         return false;
     }
+    /* Configure SPI comms as required by the sensor. */
+    // TODO: this type of channel sharing with different configurations should
+    // be handled by a wrapper class. It can also queue up traffic and call
+    // callback functions.
+    mp_spi->Init.CLKPolarity = SPI_POLARITY_HIGH;
+    mp_spi->Init.CLKPhase = SPI_PHASE_2EDGE;
+    mp_spi->Init.NSS = SPI_NSS_SOFT;
+    mp_spi->Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_32;
+    if (HAL_SPI_Init(&hspi2) != HAL_OK)
+    {
+        return false;
+    }
 
     return true;
 }
@@ -244,3 +256,9 @@ bool CBME280::startMeasument()
  *
  */
 void CBME280::applyCalibration() {}
+
+#ifdef __cplusplus
+extern "C"
+{
+    void HAL_SPI_RxCpltCallback(hspi) {}
+}

From 0f2470169661ef68a76d77ae9d6a612da0a16ece Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Thu, 28 Jul 2022 13:38:45 +0100
Subject: [PATCH 08/14] wip.

---
 Lib/Inc/CBME280.h   |  6 ++++--
 Lib/Src/CBME280.cpp | 17 ++++++++++++++++-
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/Lib/Inc/CBME280.h b/Lib/Inc/CBME280.h
index 954c6505..e76a4bfa 100644
--- a/Lib/Inc/CBME280.h
+++ b/Lib/Inc/CBME280.h
@@ -21,7 +21,7 @@
 #define P_CALIBRATION_SIZE 9
 #define H_CALIBRATION_SIZE 6
 #define RAW_ADC_DATA_SIZE  8
-#define MAX_SENSORS 2
+#define MAX_SENSORS        2
 
 class CBME280
 {
@@ -111,6 +111,7 @@ class CBME280
     void convertRawData();
     bool startMeasurement();
     void applyCalibration();
+    void receiveNewData();
 
     SPI_HandleTypeDef *mp_spi;
     CGpioWrapper m_slave_select;
@@ -123,7 +124,8 @@ class CBME280
         NEW_DATA
     } m_state;
 
-    static CBME280* sp_sensors[]
+    static CBME280 *sp_sensors[MAX_SENSORS];
+    static uint8_t s_sensor_count;
 
     uint16_t m_temperature_calibration[T_CALIBRATION_SIZE];
     uint16_t m_pressure_calibration[P_CALIBRATION_SIZE];
diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index 2ac42259..e516c7f8 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -28,6 +28,10 @@
 #define HIGH true
 #define LOW  false
 
+/* Static instance control variables. */
+CBME280 *CBME280::sp_sensors[] = {nullptr};
+uint8_t CBME280::s_sensor_count = 0;
+
 /**
  * @brief Construct a sensor driver class instance.
  *
@@ -47,6 +51,15 @@ CBME280::CBME280(SPI_HandleTypeDef *p_spi,
         Error_Handler();
     }
     m_slave_select.set(true);
+    if (s_sensor_count < MAX_SENSORS)
+    {
+        sp_sensors[s_sensor_count] = this;
+        s_sensor_count++;
+    }
+    else
+    {
+        Error_handler();
+    }
 }
 
 CBME280::~CBME280()
@@ -260,5 +273,7 @@ void CBME280::applyCalibration() {}
 #ifdef __cplusplus
 extern "C"
 {
-    void HAL_SPI_RxCpltCallback(hspi) {}
+    void HAL_SPI_RxCpltCallback(SPI_HandleTypeDef *hspi) {}
 }
+
+#endif

From 65218ba78f5eb92fb71d9541c339594d98ba9086 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Sat, 30 Jul 2022 10:32:43 +0100
Subject: [PATCH 09/14] feature: add ADC data receive functionality.

---
 Lib/Inc/CBME280.h   |  3 ++-
 Lib/Src/CBME280.cpp | 37 ++++++++++++++++++++++++++++++++++---
 2 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/Lib/Inc/CBME280.h b/Lib/Inc/CBME280.h
index e76a4bfa..65f1d871 100644
--- a/Lib/Inc/CBME280.h
+++ b/Lib/Inc/CBME280.h
@@ -106,12 +106,13 @@ class CBME280
         return m_state == MEASURING;
     }
 
+    static void processIrq();
+
 private:
     void calibrateSensor(uint8_t const *const p_calibration_data);
     void convertRawData();
     bool startMeasurement();
     void applyCalibration();
-    void receiveNewData();
 
     SPI_HandleTypeDef *mp_spi;
     CGpioWrapper m_slave_select;
diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index e516c7f8..8dc0d3fe 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -58,7 +58,7 @@ CBME280::CBME280(SPI_HandleTypeDef *p_spi,
     }
     else
     {
-        Error_handler();
+        Error_Handler();
     }
 }
 
@@ -260,7 +260,15 @@ bool CBME280::startMeasurement()
     {
         return false;
     }
-
+    m_raw_adc_data[0] = PRESS_MSB;
+    for (int i = 1; i < RAW_ADC_DATA_SIZE; i++)
+    {
+        m_raw_adc_data[i] = 0;
+    }
+    HAL_SPI_TransmitReceive_IT(mp_spi,
+                               m_raw_adc_data,
+                               m_raw_adc_data,
+                               RAW_ADC_DATA_SIZE);
     return true;
 }
 
@@ -270,10 +278,33 @@ bool CBME280::startMeasurement()
  */
 void CBME280::applyCalibration() {}
 
+/**
+ * @brief Process IRQ call for all registered and active sensors
+ *
+ */
+void CBME280::processIrq()
+{
+    uint8_t sensor = 0;
+    while ((sp_sensors[sensor] != nullptr) && sensor < s_sensor_count)
+    {
+        if (sp_sensors[sensor]->isMeasuring())
+        {
+            sp_sensors[sensor]->m_state = NEW_DATA;
+            break;
+        }
+        sensor++;
+    }
+}
+
+CBME280::processIrq();
+
 #ifdef __cplusplus
 extern "C"
 {
-    void HAL_SPI_RxCpltCallback(SPI_HandleTypeDef *hspi) {}
+    void HAL_SPI_RxCpltCallback(SPI_HandleTypeDef *hspi)
+    {
+        CBME280::processIRQ();
+    }
 }
 
 #endif

From 661c56737289a66bb0250c5309496a730f4c833c Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Sat, 30 Jul 2022 10:55:24 +0100
Subject: [PATCH 10/14] feature: enable IRQ for SPI2 engine.

---
 Core/Inc/stm32f4xx_it.h             |  1 +
 Core/Src/spi.c                      |  5 +++++
 Core/Src/stm32f4xx_it.c             | 15 +++++++++++++++
 Multichannel temperature sensor.ioc |  3 ++-
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/Core/Inc/stm32f4xx_it.h b/Core/Inc/stm32f4xx_it.h
index deb0aa40..902a5f97 100644
--- a/Core/Inc/stm32f4xx_it.h
+++ b/Core/Inc/stm32f4xx_it.h
@@ -55,6 +55,7 @@ void SVC_Handler(void);
 void DebugMon_Handler(void);
 void PendSV_Handler(void);
 void SysTick_Handler(void);
+void SPI2_IRQHandler(void);
 void USART1_IRQHandler(void);
 void USART2_IRQHandler(void);
 void DMA2_Stream0_IRQHandler(void);
diff --git a/Core/Src/spi.c b/Core/Src/spi.c
index 51b2da7a..2982ec6c 100644
--- a/Core/Src/spi.c
+++ b/Core/Src/spi.c
@@ -85,6 +85,9 @@ void HAL_SPI_MspInit(SPI_HandleTypeDef* spiHandle)
     GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
     HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 
+    /* SPI2 interrupt Init */
+    HAL_NVIC_SetPriority(SPI2_IRQn, 0, 0);
+    HAL_NVIC_EnableIRQ(SPI2_IRQn);
   /* USER CODE BEGIN SPI2_MspInit 1 */
 
   /* USER CODE END SPI2_MspInit 1 */
@@ -110,6 +113,8 @@ void HAL_SPI_MspDeInit(SPI_HandleTypeDef* spiHandle)
     */
     HAL_GPIO_DeInit(GPIOB, GPIO_PIN_10|GPIO_PIN_12|GPIO_PIN_14|GPIO_PIN_15);
 
+    /* SPI2 interrupt Deinit */
+    HAL_NVIC_DisableIRQ(SPI2_IRQn);
   /* USER CODE BEGIN SPI2_MspDeInit 1 */
 
   /* USER CODE END SPI2_MspDeInit 1 */
diff --git a/Core/Src/stm32f4xx_it.c b/Core/Src/stm32f4xx_it.c
index 4aae7358..f093fd62 100644
--- a/Core/Src/stm32f4xx_it.c
+++ b/Core/Src/stm32f4xx_it.c
@@ -56,6 +56,7 @@
 
 /* External variables --------------------------------------------------------*/
 extern DMA_HandleTypeDef hdma_adc1;
+extern SPI_HandleTypeDef hspi2;
 extern UART_HandleTypeDef huart1;
 extern UART_HandleTypeDef huart2;
 /* USER CODE BEGIN EV */
@@ -200,6 +201,20 @@ void SysTick_Handler(void)
 /* please refer to the startup file (startup_stm32f4xx.s).                    */
 /******************************************************************************/
 
+/**
+  * @brief This function handles SPI2 global interrupt.
+  */
+void SPI2_IRQHandler(void)
+{
+  /* USER CODE BEGIN SPI2_IRQn 0 */
+
+  /* USER CODE END SPI2_IRQn 0 */
+  HAL_SPI_IRQHandler(&hspi2);
+  /* USER CODE BEGIN SPI2_IRQn 1 */
+
+  /* USER CODE END SPI2_IRQn 1 */
+}
+
 /**
   * @brief This function handles USART1 global interrupt.
   */
diff --git a/Multichannel temperature sensor.ioc b/Multichannel temperature sensor.ioc
index 0ac350fe..de1522cb 100644
--- a/Multichannel temperature sensor.ioc	
+++ b/Multichannel temperature sensor.ioc	
@@ -147,6 +147,7 @@ NVIC.MemoryManagement_IRQn=true\:0\:0\:false\:false\:true\:false\:false\:true
 NVIC.NonMaskableInt_IRQn=true\:0\:0\:false\:false\:true\:false\:false\:true
 NVIC.PendSV_IRQn=true\:0\:0\:false\:false\:true\:false\:false\:true
 NVIC.PriorityGroup=NVIC_PRIORITYGROUP_4
+NVIC.SPI2_IRQn=true\:0\:0\:false\:false\:true\:true\:true\:true
 NVIC.SVCall_IRQn=true\:0\:0\:false\:false\:true\:false\:false\:true
 NVIC.SysTick_IRQn=true\:15\:0\:false\:false\:true\:false\:true\:true
 NVIC.USART1_IRQn=true\:0\:0\:false\:false\:true\:true\:true\:true
@@ -354,7 +355,7 @@ ProjectManager.FreePins=false
 ProjectManager.HalAssertFull=false
 ProjectManager.HeapSize=0x200
 ProjectManager.KeepUserCode=true
-ProjectManager.LastFirmware=true
+ProjectManager.LastFirmware=false
 ProjectManager.LibraryCopy=1
 ProjectManager.MainLocation=Core/Src
 ProjectManager.MultiThreaded=true

From e2600934970be1bdfded375f32f8a30e8c3e6fdb Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Sat, 30 Jul 2022 10:56:20 +0100
Subject: [PATCH 11/14] feature: add IRQ callback via static method.

---
 Lib/Src/CBME280.cpp | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index 8dc0d3fe..b62a9de2 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -279,7 +279,7 @@ bool CBME280::startMeasurement()
 void CBME280::applyCalibration() {}
 
 /**
- * @brief Process IRQ call for all registered and active sensors
+ * @brief Process IRQ call for all registered and active sensors.
  *
  */
 void CBME280::processIrq()
@@ -296,15 +296,7 @@ void CBME280::processIrq()
     }
 }
 
-CBME280::processIrq();
-
-#ifdef __cplusplus
-extern "C"
+void HAL_SPI_TxRxCpltCallback(SPI_HandleTypeDef *hspi)
 {
-    void HAL_SPI_RxCpltCallback(SPI_HandleTypeDef *hspi)
-    {
-        CBME280::processIRQ();
-    }
+    CBME280::processIrq();
 }
-
-#endif

From b1a5ac6319845144805701dbfcad3e31d857f623 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Sat, 30 Jul 2022 11:00:16 +0100
Subject: [PATCH 12/14] wip.

---
 Lib/Src/CBME280.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index b62a9de2..b836b941 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -136,6 +136,9 @@ bool CBME280::init()
                             SPI_TIMEOUT_MS);
     m_slave_select.set(HIGH);
     calibrateSensor(calibration_register);
+    // TODO: sensor requires setting up.
+    //  set operational mode.
+    //  set oversampling modes for all three measurements.
     return true;
 }
 

From 4254bc617bf2be226d4510b09c70276f0da31c76 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Sun, 7 Aug 2022 11:21:34 +0100
Subject: [PATCH 13/14] feature: modify calibration from integer to float.

---
 Lib/Inc/CBME280.h   |  6 +++---
 Lib/Src/CBME280.cpp | 50 +++++++++++++++++++++++++++++++++++----------
 2 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/Lib/Inc/CBME280.h b/Lib/Inc/CBME280.h
index 65f1d871..3985928a 100644
--- a/Lib/Inc/CBME280.h
+++ b/Lib/Inc/CBME280.h
@@ -128,9 +128,9 @@ class CBME280
     static CBME280 *sp_sensors[MAX_SENSORS];
     static uint8_t s_sensor_count;
 
-    uint16_t m_temperature_calibration[T_CALIBRATION_SIZE];
-    uint16_t m_pressure_calibration[P_CALIBRATION_SIZE];
-    uint16_t m_humidity_calibration[H_CALIBRATION_SIZE];
+    float m_temperature_calibration[T_CALIBRATION_SIZE];
+    float m_pressure_calibration[P_CALIBRATION_SIZE];
+    float m_humidity_calibration[H_CALIBRATION_SIZE];
 
     uint8_t m_raw_adc_data[RAW_ADC_DATA_SIZE];
     uint32_t m_raw_temperature_data;
diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index b836b941..89189bae 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -11,6 +11,7 @@
  */
 
 #include <CBME280.h>
+#include <math.h>
 
 #define BME280_ID             0x60
 #define BMP280_ID             0x58
@@ -28,6 +29,25 @@
 #define HIGH true
 #define LOW  false
 
+/* These values were extracted from BME280 calibration source code. The original
+ * calibration source code was intended for use with integers to allow its use
+ * on resource constrained MCUs. This code will run on MCU with floating point
+ * unit, so converting into float calibration increases dynamic range and make
+ * code much more readable and maintainable.
+ */
+constexpr float T_CALIB_CORRECTION[] = {1, 1 / 1024, 1 / sqrt(8092)};
+constexpr float P_CALIB_CORRECTION[] = {1 / 6250,
+                                        1 / 524288 / 32768,
+                                        1 / 524288 / 524288 / 32768,
+                                        65536 / 4096,
+                                        1 / 2 / 4096,
+                                        1 / 32768 / 4 / 4096,
+                                        1 / 16,
+                                        1 / 32768 / 16,
+                                        1 / 2147483648 / 16};
+constexpr float H_CALIB_CORRECTION[] =
+    {-1 / 524288, 1 / 65536, 1 / 67108864, -1 / 64, 1 / 16384, 1 / 67108864};
+
 /* Static instance control variables. */
 CBME280 *CBME280::sp_sensors[] = {nullptr};
 uint8_t CBME280::s_sensor_count = 0;
@@ -185,16 +205,19 @@ bool CBME280::run()
 void CBME280::calibrateSensor(uint8_t const *const p_calibration_data)
 {
     uint8_t const *p_runner = p_calibration_data;
+    uint32_t raw_calibration;
     for (int i = 0; i < T_CALIBRATION_SIZE; i++)
     {
-        m_temperature_calibration[i] = *p_runner;
-        m_temperature_calibration[i] |= *(++p_runner) << 8;
+        raw_calibration = m_temperature_calibration[i] = *p_runner;
+        raw_calibration |= *(++p_runner) << 8;
+        m_temperature_calibration[i] = raw_calibration * T_CALIB_CORRECTION[i];
         ++p_runner;
     }
     for (int i = 0; i < P_CALIBRATION_SIZE; i++)
     {
-        m_pressure_calibration[i] = *p_runner;
-        m_pressure_calibration[i] |= *(++p_runner) << 8;
+        raw_calibration = *p_runner;
+        raw_calibration |= *(++p_runner) << 8;
+        m_pressure_calibration[i] = raw_calibration * P_CALIB_CORRECTION[i];
         ++p_runner;
     }
     /* Humidity calibration data is spread around and is stored in a weird
@@ -204,15 +227,20 @@ void CBME280::calibrateSensor(uint8_t const *const p_calibration_data)
     /* I am certain the engineer at Bosch who came up with this had management
      * breathing down their neck. One day they stopped caring and made this
      * monstrocity.*/
-    m_humidity_calibration[0] = p_calibration_data[25];
-    m_humidity_calibration[1] =
-        (p_calibration_data[27] << 8) + p_calibration_data[26];
-    m_humidity_calibration[2] = p_calibration_data[28];
-    m_humidity_calibration[3] =
+    raw_calibration = p_calibration_data[25];
+    m_humidity_calibration[0] = raw_calibration * H_CALIB_CORRECTION[0];
+    raw_calibration = (p_calibration_data[27] << 8) + p_calibration_data[26];
+    m_humidity_calibration[1] = raw_calibration * H_CALIB_CORRECTION[1];
+    raw_calibration = p_calibration_data[28];
+    m_humidity_calibration[2] = raw_calibration * H_CALIB_CORRECTION[2];
+    raw_calibration =
         (p_calibration_data[29] << 4) + (p_calibration_data[30] & 0x0F);
-    m_humidity_calibration[4] =
+    m_humidity_calibration[3] = raw_calibration * H_CALIB_CORRECTION[3];
+    raw_calibration =
         (p_calibration_data[31] << 4) + (p_calibration_data[30] >> 4);
-    m_humidity_calibration[5] = p_calibration_data[32];
+    m_humidity_calibration[4] = raw_calibration * H_CALIB_CORRECTION[4];
+    raw_calibration = p_calibration_data[32];
+    m_humidity_calibration[5] = raw_calibration * H_CALIB_CORRECTION[5];
 }
 
 /**

From d37fde7d74be5a2a563f70c0f3ccb41a42aec4d2 Mon Sep 17 00:00:00 2001
From: Salavat Magazov <s.magazov@gmail.com>
Date: Sun, 7 Aug 2022 12:16:00 +0100
Subject: [PATCH 14/14] feature: implement raw data calibration for T, P, and H
 measurements.

---
 Lib/Inc/CBME280.h   |  5 ++-
 Lib/Src/CBME280.cpp | 87 ++++++++++++++++++++++++++++++++++++---------
 2 files changed, 75 insertions(+), 17 deletions(-)

diff --git a/Lib/Inc/CBME280.h b/Lib/Inc/CBME280.h
index 3985928a..76186f15 100644
--- a/Lib/Inc/CBME280.h
+++ b/Lib/Inc/CBME280.h
@@ -112,7 +112,9 @@ class CBME280
     void calibrateSensor(uint8_t const *const p_calibration_data);
     void convertRawData();
     bool startMeasurement();
-    void applyCalibration();
+    void calculateT();
+    void calculateP();
+    void calculateH();
 
     SPI_HandleTypeDef *mp_spi;
     CGpioWrapper m_slave_select;
@@ -137,6 +139,7 @@ class CBME280
     uint32_t m_raw_pressure_data;
     uint32_t m_raw_humidity_data;
 
+    float m_t_fine;
     float m_temperature;
     float m_pressure;
     float m_humidity;
diff --git a/Lib/Src/CBME280.cpp b/Lib/Src/CBME280.cpp
index 89189bae..7d26ce80 100644
--- a/Lib/Src/CBME280.cpp
+++ b/Lib/Src/CBME280.cpp
@@ -48,6 +48,11 @@ constexpr float P_CALIB_CORRECTION[] = {1 / 6250,
 constexpr float H_CALIB_CORRECTION[] =
     {-1 / 524288, 1 / 65536, 1 / 67108864, -1 / 64, 1 / 16384, 1 / 67108864};
 
+constexpr float T_SCALE_FACTOR = 1 / 5120;
+constexpr float P_OFFSET_1 = 64000;
+constexpr float P_OFFSET_2 = 1048576;
+constexpr float H_OFFSET = 76800;
+
 /* Static instance control variables. */
 CBME280 *CBME280::sp_sensors[] = {nullptr};
 uint8_t CBME280::s_sensor_count = 0;
@@ -186,8 +191,12 @@ bool CBME280::run()
             // busy waiting for SPI interrupt to fire.
             break;
         case NEW_DATA:
-            convertRawData();
-            applyCalibration();
+            /* The sequence of these method calls must be preserved since
+             * temperature is used in pressure and humidity calculations.
+             * convertRawData();*/
+            calculateT();
+            calculateP();
+            calculateH();
             b_new_data = true;
             break;
         default:
@@ -220,13 +229,13 @@ void CBME280::calibrateSensor(uint8_t const *const p_calibration_data)
         m_pressure_calibration[i] = raw_calibration * P_CALIB_CORRECTION[i];
         ++p_runner;
     }
-    /* Humidity calibration data is spread around and is stored in a weird
-     * convoluted way. See the manual. This recovery was copied with
-     * modifications from the Bosch github repository.
+    /* Humidity calibration data is spread around and is stored in a
+     * weird convoluted way. See the manual. This recovery was
+     * copied with modifications from the Bosch github repository.
      * https://github.com/BoschSensortec/BME280_driver */
-    /* I am certain the engineer at Bosch who came up with this had management
-     * breathing down their neck. One day they stopped caring and made this
-     * monstrocity.*/
+    /* I am certain the engineer at Bosch who came up with this had
+     * management breathing down their neck. One day they stopped
+     * caring and made this monstrocity.*/
     raw_calibration = p_calibration_data[25];
     m_humidity_calibration[0] = raw_calibration * H_CALIB_CORRECTION[0];
     raw_calibration = (p_calibration_data[27] << 8) + p_calibration_data[26];
@@ -244,10 +253,11 @@ void CBME280::calibrateSensor(uint8_t const *const p_calibration_data)
 }
 
 /**
- * @brief Convert raw data from sensor registers into corresponding unprocessed
- * sensor values.
+ * @brief Convert raw data from sensor registers into corresponding
+ * unprocessed sensor values.
  *
- * @param p_raw_adc_data Pointer to raw data stream of 8 8-bit values.
+ * @param p_raw_adc_data Pointer to raw data stream of 8 8-bit
+ * values.
  */
 void CBME280::convertRawData()
 {
@@ -280,9 +290,9 @@ bool CBME280::startMeasurement()
         return false;
     }
     /* Configure SPI comms as required by the sensor. */
-    // TODO: this type of channel sharing with different configurations should
-    // be handled by a wrapper class. It can also queue up traffic and call
-    // callback functions.
+    // TODO: this type of channel sharing with different
+    // configurations should be handled by a wrapper class. It can
+    // also queue up traffic and call callback functions.
     mp_spi->Init.CLKPolarity = SPI_POLARITY_HIGH;
     mp_spi->Init.CLKPhase = SPI_PHASE_2EDGE;
     mp_spi->Init.NSS = SPI_NSS_SOFT;
@@ -304,10 +314,55 @@ bool CBME280::startMeasurement()
 }
 
 /**
- * @brief Apply calibration to raw data.
+ * @brief Apply temperature calibration to raw data.
+ *
+ */
+void CBME280::calculateT()
+{
+    float t;
+    t = (m_raw_temperature_data / 16 - m_temperature_calibration[0]);
+    m_t_fine =
+        t * m_temperature_calibration[1] + t * t * m_temperature_calibration[2];
+    m_temperature = m_t_fine / T_SCALE_FACTOR;
+}
+
+/**
+ * @brief Apply pressure calibration to raw data.
  *
  */
-void CBME280::applyCalibration() {}
+void CBME280::calculateP()
+{
+    float t_p = m_t_fine / 2 - P_OFFSET_1;
+    float var_1 = m_pressure_calibration[3];
+    var_1 += t_p * m_pressure_calibration[4];
+    var_1 += t_p * t_p * m_pressure_calibration[5];
+    float var_2 = 1;
+    var_2 += t_p * m_pressure_calibration[1];
+    var_2 += t_p * t_p * m_pressure_calibration[2];
+    var_2 *= m_pressure_calibration[0];
+    float var_3 = P_OFFSET_2 - m_raw_pressure_data - var_1;
+    var_3 /= var_2;
+    m_pressure = m_pressure_calibration[6];
+    m_pressure += var_3 * m_pressure_calibration[7];
+    m_pressure += var_3 * var_3 * m_pressure_calibration[8];
+}
+
+/**
+ * @brief Apply humidity calibration to raw data.
+ *
+ */
+void CBME280::calculateH()
+{
+    float t_h = m_t_fine - H_OFFSET;
+    float var_1 = 1 + t_h * m_humidity_calibration[2];
+    var_1 *= t_h * m_humidity_calibration[5];
+    var_1 += 1;
+    var_1 *= m_humidity_calibration[1];
+    var_1 *= m_raw_humidity_data + m_humidity_calibration[3] +
+             t_h * m_humidity_calibration[4];
+    m_humidity = var_1;
+    m_humidity += var_1 * var_1 * m_humidity_calibration[0];
+}
 
 /**
  * @brief Process IRQ call for all registered and active sensors.