daplink_bridge

DAPLink Bridge MicroPython Driver

Low-level I2C bridge driver for the STM32F103 DAPLink interface on the STeaMi board.

This driver handles all direct I2C communication with the bridge: device identification, status/error registers, busy polling, and persistent config zone access (1 KB internal flash).

I2C Address

Default 7-bit I2C address: 0x3B

Basic Usage

from machine import I2C
from daplink_bridge import DaplinkBridge

i2c = I2C(1)
bridge = DaplinkBridge(i2c)

print("WHO_AM_I:", hex(bridge.device_id()))
print("Busy:", bridge.busy())

API

Initialization

bridge = DaplinkBridge(i2c, address=0x3B)

Create a new DAPLink bridge instance.

Parameters:

• i2c: initialized MicroPython I2C bus
• address: I2C address of the bridge, default is 0x3B

Device identification

device_id()

bridge.device_id()

Read the WHO_AM_I register. Expected value: 0x4C.

Status

busy()

bridge.busy()

Returns True if the bridge is currently busy, otherwise False.

Config zone

The config zone is a 1 KB persistent storage area in the STM32F103 internal flash. It is separate from the external flash file storage and survives clear_flash() operations.

clear_config()

bridge.clear_config()

Erase the entire config zone. Raises OSError if the operation fails.

write_config(data, offset=0)

bridge.write_config("board_rev=3", offset=0)
bridge.write_config(b"\x01\x02\x03", offset=100)

Write data into the config zone at the given byte offset.

Parameters:

• data: str or bytes
• offset: byte offset in the range 0 to 1023

Notes:

• existing data outside the written range is preserved
• raises ValueError if the write would go out of bounds
• raises OSError if the bridge reports a write error

read_config()

cfg = bridge.read_config()

Read back config zone content.

Returns:

• bytes up to the first 0xFF
• b"" if the config zone is empty

Architecture

steami_config  ──┐
                 ├──→  daplink_bridge  ──→  I2C (STM32F103)
daplink_flash  ──┘

• daplink_flash — high-level flash file operations
• steami_config — persistent board configuration (JSON)

Notes

• The bridge uses a WHO_AM_I value of 0x4C.
• The config zone (1 KB) is separate from the external flash file area.
• All I2C operations go through private helpers (_read_reg, _write_reg, _writeto, _readfrom).