#!/usr/bin/env python3

import struct
import serial

# -----------------------------------------------------------------------------
# Configuration
# -----------------------------------------------------------------------------

PORT = "/dev/ttyACM1"
BAUDRATE = 115200

COMMAND_PREFIX = 0x69
COMMAND_ID = 0x00

COMMAND_RESET_OFFSET = 10

# Length
length = 0

# -----------------------------------------------------------------------------
# Build packet with placeholder CRC
# -----------------------------------------------------------------------------

packet = bytearray([
    COMMAND_PREFIX,
    length,
    COMMAND_ID,
    COMMAND_RESET_OFFSET,
    0x00,      # Placeholder CRC
])

# -----------------------------------------------------------------------------
# Calculate CRC (matches command_calculate_crc())
#
# Sum every byte except the CRC byte itself.
# -----------------------------------------------------------------------------

crc_sum = 0

for i, byte in enumerate(packet):
    if i == 4:      # Skip CRC field
        continue
    crc_sum += byte

packet[4] = 0x100 - (crc_sum & 0xFF)
# Equivalent to:
# packet[4] = (0x100 - (crc_sum & 0xFF)) & 0xFF

# -----------------------------------------------------------------------------
# Send
# -----------------------------------------------------------------------------

print(f"Packet ({len(packet)} bytes):")
print(packet.hex(" "))

with serial.Serial(PORT, BAUDRATE, timeout=1) as ser:
    ser.write(packet)
    ser.flush()

print("Done.")