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DAPLink Flash MicroPython Driver

High-level flash file operations for the STeaMi board, built on top of the daplink_bridge module.

This driver provides 8.3 filename management, data writing, and sector-based reading for the external W25Q64JV SPI flash connected via the STM32F103 DAPLink bridge.

Dependencies

  • daplink_bridge — low-level I2C bridge communication

Basic Usage

from machine import I2C
from daplink_bridge import DaplinkBridge
from daplink_flash import DaplinkFlash

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

flash.set_filename("LOG", "TXT")
flash.clear_flash()

flash.write_line("Hello from STeaMi!")
flash.write_line("DAPLink flash test")

content = flash.read()
print(content.decode())

API

Initialization

flash = DaplinkFlash(bridge)

Create a new DAPLink flash driver instance.

Parameters:

  • bridge: a DaplinkBridge instance

Filename management

set_filename(name, ext)

flash.set_filename("DATA", "CSV")

Set the current file name using the DOS 8.3 format.

Parameters:

  • name: file name, up to 8 characters
  • ext: extension, up to 3 characters

The driver automatically uppercases and pads the values as needed.

get_filename()

flash.get_filename()

Returns the current file name as:

(name, ext)

Flash operations

clear_flash()

flash.clear_flash()

Erase the entire external flash memory.

This removes the stored file content. The config zone (managed by DaplinkBridge) is not affected.

write(data)

flash.write("hello")
flash.write(b"world")

Append data to the current file.

Parameters:

  • data: str or bytes

Returns:

  • number of bytes written

Notes:

  • strings are automatically encoded to bytes
  • large writes are automatically split into protocol-sized chunks
  • raises OSError if the bridge reports a write error

write_line(text)

flash.write_line("temperature;humidity;pressure")

Append a line of text followed by \n.

Returns:

  • number of bytes written

Read operations

read_sector(sector)

data = flash.read_sector(0)

Read one raw 256-byte sector from flash.

Parameters:

  • sector: sector number from 0 to 32767

Returns:

  • bytes object of length 256

This is useful for low-level inspection of flash content.

read(length=None)

content = flash.read()
content = flash.read(128)

Read file data from flash.

Parameters:

  • length: optional maximum number of bytes to read

Returns:

  • file content as bytes

Behavior:

  • if length is None, the driver reads until the first 0xFF
  • if length is provided, it reads up to that many bytes

Examples

Example Description
flash_info.py Display bridge ID, status, error register, busy flag, and filename
write_csv.py Create a CSV file in flash, write a few lines, then read it back
read_file.py Read and display the currently stored file
erase_flash.py Erase the external flash memory
sensor_log.py Log simulated sensor data to CSV, read it back, and compute statistics
config_zone.py Test and demonstrate persistent config zone operations

Notes

  • Flash file data is written to external memory through the DAPLink STM32F103 bridge.
  • The config zone is managed separately by DaplinkBridge and survives clear_flash() operations.
  • File naming follows the classic 8.3 format: up to 8 characters for the base name and 3 for the extension.
  • For bridge-level operations (device ID, status, config zone), see the daplink_bridge documentation.

Example mount command

mpremote mount lib run lib/daplink_flash/examples/flash_info.py