circuitpython.patch

diff --git a/shared-module/onewireio/OneWire.c b/shared-module/onewireio/OneWire.c
index aeb4dcb00..162321859 100644
--- a/shared-module/onewireio/OneWire.c
+++ b/shared-module/onewireio/OneWire.c
@@ -29,12 +29,17 @@
 #include "shared-bindings/microcontroller/__init__.h"
 #include "shared-bindings/digitalio/DigitalInOut.h"
 
+#include "ports/raspberrypi/sdk/src/rp2_common/hardware_timer/include/hardware/timer.h"
+#include "ports/raspberrypi/sdk/src/rp2_common/hardware_gpio/include/hardware/gpio.h"
+
 // Durations are taken from here: https://www.maximintegrated.com/en/app-notes/index.mvp/id/126
 
 void common_hal_onewireio_onewire_construct(onewireio_onewire_obj_t *self,
     const mcu_pin_obj_t *pin) {
     self->pin.base.type = &digitalio_digitalinout_type;
     common_hal_digitalio_digitalinout_construct(&self->pin, pin);
+    common_hal_digitalio_digitalinout_switch_to_output(&self->pin, false, DRIVE_MODE_OPEN_DRAIN);
+    gpio_set_dir(self->pin.pin->number, GPIO_IN); // od high
 }
 
 bool common_hal_onewireio_onewire_deinited(onewireio_onewire_obj_t *self) {
@@ -52,38 +57,43 @@ void common_hal_onewireio_onewire_deinit(onewireio_onewire_obj_t *self) {
 // to do accurate timekeeping, since we disable interrupts during the delays below.
 
 bool common_hal_onewireio_onewire_reset(onewireio_onewire_obj_t *self) {
+    const uint8_t pin = self->pin.pin->number;
+    gpio_set_dir(pin, GPIO_OUT); // od low
+    busy_wait_us_32(70);
     common_hal_mcu_disable_interrupts();
-    common_hal_digitalio_digitalinout_switch_to_output(&self->pin, false, DRIVE_MODE_OPEN_DRAIN);
-    common_hal_mcu_delay_us(480);
-    common_hal_digitalio_digitalinout_switch_to_input(&self->pin, PULL_NONE);
-    common_hal_mcu_delay_us(70);
-    bool value = common_hal_digitalio_digitalinout_get_value(&self->pin);
-    common_hal_mcu_delay_us(410);
+    gpio_set_dir(pin, GPIO_IN); // od high
+    busy_wait_us_32(9);
+    bool value = gpio_get(pin);
     common_hal_mcu_enable_interrupts();
+    busy_wait_us_32(40);
     return value;
 }
 
 bool common_hal_onewireio_onewire_read_bit(onewireio_onewire_obj_t *self) {
+    const uint8_t pin = self->pin.pin->number;
+    gpio_set_dir(pin, GPIO_IN); // od high
     common_hal_mcu_disable_interrupts();
-    common_hal_digitalio_digitalinout_switch_to_output(&self->pin, false, DRIVE_MODE_OPEN_DRAIN);
-    common_hal_mcu_delay_us(6);
-    common_hal_digitalio_digitalinout_switch_to_input(&self->pin, PULL_NONE);
-    // TODO(tannewt): Test with more devices and maybe make the delays
-    // configurable. This should be 9 by the datasheet but all bits read as 1
-    // then.
-    common_hal_mcu_delay_us(6);
-    bool value = common_hal_digitalio_digitalinout_get_value(&self->pin);
-    common_hal_mcu_delay_us(55);
+    gpio_set_dir(pin, GPIO_OUT); // od low
+    // this generates a 0.75us delay...
+    gpio_set_dir(pin, GPIO_IN); // od high
+    asm volatile("nop\nnop\nnop\nnop\nnop\nnop\nnop\nnop");
+    bool value = gpio_get(pin);
     common_hal_mcu_enable_interrupts();
+    busy_wait_us_32(9);
     return value;
 }
 
 void common_hal_onewireio_onewire_write_bit(onewireio_onewire_obj_t *self,
     bool bit) {
+    const uint8_t pin = self->pin.pin->number;
     common_hal_mcu_disable_interrupts();
-    common_hal_digitalio_digitalinout_switch_to_output(&self->pin, false, DRIVE_MODE_OPEN_DRAIN);
-    common_hal_mcu_delay_us(bit? 6 : 60);
-    common_hal_digitalio_digitalinout_switch_to_input(&self->pin, PULL_NONE);
-    common_hal_mcu_delay_us(bit? 64 : 10);
+    gpio_set_dir(pin, GPIO_OUT); // od low
+    // this generates a 0.75us delay...
+    if (bit) {
+        gpio_set_dir(pin, GPIO_IN); // od high
+    }
+    busy_wait_us_32(6);
+    gpio_set_dir(pin, GPIO_IN); // od high
+    busy_wait_us_32(3);
     common_hal_mcu_enable_interrupts();
 }