refactor(daplink_flash): Split into daplink_bridge + daplink_flash layers.

.gitignore

@@ -9,3 +9,4 @@ node_modules/
 CLAUDE.md
 .build/
 .venv/
+.claude/

.vscode/settings.json

@@ -6,6 +6,7 @@
         "lib/apds9960",
         "lib/bme280",
         "lib/bq27441",
+        "lib/daplink_bridge",
         "lib/daplink_flash",
         "lib/gc9a01",
         "lib/hts221",

README.md

@@ -14,7 +14,8 @@ This repository contains all the drivers for the main components of the [STeaMi]
 | Component     | Driver                                         | I2C Address | Description                           |
 | ------------- | ---------------------------------------------- | ----------- | ------------------------------------- |
 | BQ27441-G1    | [`bq27441`](lib/bq27441/README.md)             | `0x55`      | Battery fuel gauge                    |
-| DAPLink Flash | [`daplink_flash`](lib/daplink_flash/README.md) | `0x3B`      | I2C-to-SPI flash bridge + config zone |
+| DAPLink Bridge | [`daplink_bridge`](lib/daplink_bridge/)        | `0x3B`      | I2C bridge to STM32F103 + config zone |
+| DAPLink Flash | [`daplink_flash`](lib/daplink_flash/README.md) | —           | Flash file operations via bridge      |
 | SSD1327       | [`ssd1327`](lib/ssd1327/README.md)             | — (SPI)     | 128x128 greyscale OLED display        |
 | MCP23009E     | [`mcp23009e`](lib/mcp23009e/README.md)         | `0x20`      | 8-bit I/O expander (D-PAD)            |
 | VL53L1X       | [`vl53l1x`](lib/vl53l1x/README.md)             | `0x29`      | Time-of-Flight distance sensor        |

lib/daplink_bridge/daplink_bridge/__init__.py

@@ -0,0 +1,5 @@
+from daplink_bridge.device import DaplinkBridge
+
+__all__ = [
+    "DaplinkBridge",
+]

lib/daplink_bridge/daplink_bridge/const.py

@@ -0,0 +1,29 @@
+from micropython import const
+
+# I2C address (7-bit) — 0x76 in 8-bit (CODAL convention)
+DAPLINK_BRIDGE_DEFAULT_ADDR = const(0x3B)
+
+# WHO_AM_I expected value
+DAPLINK_BRIDGE_WHO_AM_I_VAL = const(0x4C)
+
+# Commands — bridge level
+CMD_WHO_AM_I = const(0x01)
+CMD_WRITE_CONFIG = const(0x30)
+CMD_READ_CONFIG = const(0x31)
+CMD_CLEAR_CONFIG = const(0x32)
+
+# Registers
+REG_STATUS = const(0x80)
+REG_ERROR = const(0x81)
+
+# Status register bits
+STATUS_BUSY = const(0x80)
+
+# Error register bits
+ERROR_BAD_PARAM = const(0x01)
+ERROR_CMD_FAILED = const(0x80)
+
+# Protocol limits
+MAX_WRITE_CHUNK = const(30)
+SECTOR_SIZE = const(256)
+CONFIG_SIZE = const(1024)

lib/daplink_bridge/daplink_bridge/device.py

@@ -0,0 +1,143 @@
+from time import sleep_ms
+
+from daplink_bridge.const import *
+
+
+class DaplinkBridge(object):
+    """Low-level I2C bridge to the STM32F103 DAPLink interface."""
+
+    def __init__(self, i2c, address=DAPLINK_BRIDGE_DEFAULT_ADDR):
+        self.i2c = i2c
+        self.address = address
+        self._buffer_1 = bytearray(1)
+
+    # --------------------------------------------------
+    # Low level I2C
+    # --------------------------------------------------
+
+    def _read_reg(self, reg, n=1):
+        """Read n bytes from register."""
+        if n == 1:
+            self.i2c.readfrom_mem_into(self.address, reg, self._buffer_1)
+            return self._buffer_1[0]
+        return self.i2c.readfrom_mem(self.address, reg, n)
+
+    def _write_reg(self, reg, data):
+        """Write data bytes to register."""
+        self.i2c.writeto_mem(self.address, reg, data)
+
+    def _write_cmd(self, cmd):
+        """Write a single command byte (no payload)."""
+        self._buffer_1[0] = cmd
+        self.i2c.writeto(self.address, self._buffer_1)
+
+    def _writeto(self, data):
+        """Write raw data frame to the bridge."""
+        self.i2c.writeto(self.address, data)
+
+    def _readfrom(self, n):
+        """Read n raw bytes from the bridge."""
+        return self.i2c.readfrom(self.address, n)
+
+    # --------------------------------------------------
+    # Device identification
+    # --------------------------------------------------
+
+    def device_id(self):
+        """Read WHO_AM_I register. Expected: 0x4C."""
+        return self._read_reg(CMD_WHO_AM_I)
+
+    # --------------------------------------------------
+    # Status and error registers
+    # --------------------------------------------------
+
+    def _status(self):
+        """Read raw status register."""
+        return self._read_reg(REG_STATUS)
+
+    def _error(self):
+        """Read raw error register."""
+        return self._read_reg(REG_ERROR)
+
+    def busy(self):
+        """Return True if bridge is busy."""
+        return bool(self._status() & STATUS_BUSY)
+
+    def _wait_busy(self, timeout_ms=30000):
+        """Poll busy bit until clear. Raises OSError on timeout."""
+        elapsed = 0
+        while self.busy():
+            sleep_ms(5)
+            elapsed += 5
+            if elapsed >= timeout_ms:
+                raise OSError("DAPLink bridge busy timeout")
+
+    # --------------------------------------------------
+    # Config zone (1 KB persistent storage in F103 internal flash)
+    # --------------------------------------------------
+
+    def clear_config(self):
+        """Erase the 1 KB config zone."""
+        self._wait_busy()
+        self._write_cmd(CMD_CLEAR_CONFIG)
+        sleep_ms(100)
+        self._wait_busy()
+        err = self._error()
+        if err:
+            raise OSError("DAPLink config clear error: 0x{:02X}".format(err))
+
+    def write_config(self, data, offset=0):
+        """Write data to the config zone at the given offset.
+
+        Args:
+            data: bytes or str to store.
+            offset: byte offset within the config zone (0-1023).
+        """
+        if isinstance(data, str):
+            data = data.encode()
+        length = len(data)
+        if offset < 0 or offset >= CONFIG_SIZE:
+            raise ValueError("offset out of range: {}".format(offset))
+        if offset + length > CONFIG_SIZE:
+            raise ValueError("data exceeds config zone boundary")
+        buf = bytearray(MAX_WRITE_CHUNK + 2)
+        max_payload = len(buf) - 4
+        buf[0] = CMD_WRITE_CONFIG
+        pos = 0
+        while pos < length:
+            self._wait_busy()
+            chunk_len = min(max_payload, length - pos)
+            cur_offset = offset + pos
+            buf[1] = (cur_offset >> 8) & 0xFF
+            buf[2] = cur_offset & 0xFF
+            buf[3] = chunk_len
+            buf[4 : 4 + chunk_len] = data[pos : pos + chunk_len]
+            for i in range(4 + chunk_len, len(buf)):
+                buf[i] = 0
+            self.i2c.writeto(self.address, buf)
+            sleep_ms(50)
+            pos += chunk_len
+        self._wait_busy()
+        err = self._error()
+        if err:
+            raise OSError("DAPLink config write error: 0x{:02X}".format(err))
+
+    def read_config(self):
+        """Read config zone content.
+
+        Returns:
+            bytes: config data up to first 0xFF, or b'' if empty.
+        """
+        result = bytearray()
+        for page_offset in range(0, CONFIG_SIZE, SECTOR_SIZE):
+            self._wait_busy()
+            hi = (page_offset >> 8) & 0xFF
+            lo = page_offset & 0xFF
+            self._write_reg(CMD_READ_CONFIG, bytes([hi, lo]))
+            sleep_ms(100)
+            data = self.i2c.readfrom(self.address, SECTOR_SIZE)
+            for i in range(SECTOR_SIZE):
+                if data[i] == 0xFF:
+                    return bytes(result)
+                result.append(data[i])
+        return bytes(result)

lib/daplink_bridge/manifest.py

@@ -0,0 +1,6 @@
+metadata(
+    description="Low-level I2C bridge driver for the STM32F103 DAPLink interface.",
+    version="0.0.1",
+)
+
+package("daplink_bridge")

lib/daplink_flash/daplink_flash/const.py

@@ -1,39 +1,15 @@
 from micropython import const
 
-# I2C address (7-bit) — 0x76 in 8-bit (CODAL convention)
-DAPLINK_FLASH_DEFAULT_ADDR = const(0x3B)
-
-# WHO_AM_I expected value
-DAPLINK_FLASH_WHO_AM_I_VAL = const(0x4C)
-
-# Commands
-CMD_WHO_AM_I = const(0x01)
+# Commands — flash level
 CMD_SET_FILENAME = const(0x03)
 CMD_GET_FILENAME = const(0x04)
 CMD_CLEAR_FLASH = const(0x10)
 CMD_WRITE_DATA = const(0x11)
 CMD_READ_SECTOR = const(0x20)
-CMD_WRITE_CONFIG = const(0x30)
-CMD_READ_CONFIG = const(0x31)
-CMD_CLEAR_CONFIG = const(0x32)
-
-# Registers
-REG_STATUS = const(0x80)
-REG_ERROR = const(0x81)
-
-# Status register bits
-STATUS_BUSY = const(0x80)
-
-# Error register bits
-ERROR_BAD_PARAM = const(0x01)
-ERROR_FILE_FULL = const(0x20)
-ERROR_BAD_FILENAME = const(0x40)
-ERROR_CMD_FAILED = const(0x80)
 
 # Protocol limits
 MAX_WRITE_CHUNK = const(30)
 SECTOR_SIZE = const(256)
 MAX_SECTORS = const(32768)
-CONFIG_SIZE = const(1024)
 FILENAME_LEN = const(8)
 EXT_LEN = const(3)