MicroPython command reference

Complete native LIN API, master, multiple slave IDs, passive sniffer, examples and firmware updates.

Complete MicroPython command reference

The STM32G0B0 provides independent LIN1 and LIN2 channels. Time-critical LIN functionality and LEDs are native C; MicroPython is the scripting interface. These features are available on firmware main.

All commands

Command	Description
`lin.init(ch, baud)`	1/2; 1000–20000 baud
`lin.send(ch, id, data, enhanced=True)`	0–8 bytes; master publish
`lin.request(ch, id, length, enhanced=True)`	0–8 bytes; returns bytes, checks checksum
`lin.request_raw(ch, id, length)`	1–9 raw bytes including checksum, no validation
`lin.slave_set(ch, id, data, enhanced=True)`	Up to 64 slave IDs per channel
`lin.slave_clear(ch, id)`	Remove one configured slave ID
`lin.slave_clear(ch)`	Remove all slave IDs
`lin.sniffer_set(ch, id, length, enhanced=True)`	Monitor selected ID, fixed data length 0–8
`lin.sniffer_clear(ch)`	Clear monitoring rules
`lin.sniffer(ch, True/False)`	Enable/disable passive sniffer
`lin.recv(ch)`	Pop oldest frame dict or `None`
`lin.tic()`	Current 64-bit microsecond tick

ch is 1 or 2, and id is 0x00–0x3F. The default checksum mode is Enhanced; enhanced=False selects Classic. Exceptions include OSError and ValueError. The C implementation prevents a channel from combining passive sniffing with active master or slave functionality.

Example: Multiple slave IDs

import lin
lin.init(1, 19200)
lin.init(2, 19200)
lin.slave_clear(2)
lin.slave_set(2, 0x12, b'\x11\x22\x33\x44')
lin.slave_set(2, 0x23, b'\x55\x66')
print(lin.request(1, 0x12, 4))
print(lin.request(1, 0x23, 2))
print(lin.recv(1))
print(lin.recv(2))
lin.slave_clear(2, 0x23)

Example: Passive filtered monitor

import lin
lin.init(1, 19200)
lin.init(2, 19200)
lin.slave_clear(2)
lin.sniffer_clear(2)
lin.sniffer_set(2, 0x12, 4)
lin.sniffer_set(2, 0x23, 2, False)
lin.sniffer(2, True)
lin.send(1, 0x12, b'\x11\x22\x33\x44')
lin.send(1, 0x35, b'\xAA\xBB')  # ignored
while True:
    frame = lin.recv(2)
    if frame is None:
        break
    print(frame)
lin.sniffer(2, False)

The sniffer never transmits; it only captures configured IDs with specified lengths and checksums. Ensure correct LIN bus supply/pull-up when using the two-channel loopback example.

Example: TIC and frame timing

import lin, time
a = lin.tic()
time.sleep_ms(150)
print('us:', lin.tic()-a)
f = lin.recv(1)
if f:
    print(f['tic_start'], f['tic_duration'], f['status'])

Frames contain id, len, data, 64-bit tic_start, 32-bit tic_duration (microseconds), and status (0 valid, 1 sniffer checksum error). FIFOs hold 15 usable frames per channel, dropping the oldest on overflow. TIC is not wall-clock time: see the dedicated TIC page.

Raspberry Pi CLI and flashing

cd ~/be-iis-lin
./.venv/bin/beiis-lin --direct info
./.venv/bin/beiis-lin --direct exec "import lin; print(lin.tic())"
git switch main
git pull --ff-only
make host
make firmware-all
make test
make flash-i2c

I²C address is 0x42 on bus 1 by default. The Raw-REPL result timeout is 5 seconds by default; longer scripts need a larger timeout in host/beiis_lin/raw_repl.py. flash-i2c enters mboot via the running MicroPython application, writes/verifies the application and restarts it. For SWD recovery see Firmware & Flashing. Avoid programming the bootloader during routine updates.

Native LEDs and known limits

MASTER/TX/RX pulses remain visible for at least 50 ms; SLAVE stays lit while slave IDs are configured. All eight active-low LEDs run in native C; no MicroPython LED command exists. Unknown-length monitoring, incomplete-frame capture, diagnostic transport, scheduling and sleep/wakeup are not complete.

LIN overview · TIC · Source