sprout.py

#!/usr/bin/env python3
import struct
import sys
import serial

PORT_DEFAULT = "/dev/ttyUSB0"
BAUD = 115200

ROTATE_ID = 0x28          # fixed/reused
ROTATE_OPCODE = 0x08

# Known-good captured packet
LIGHT_ON = bytes.fromhex("1E 11 00 00 01 02 01 00 00 00 00 00 1F 13 01 00")

COMMON_ANGLES = [45, 90, 180, 360]


def hexdump(b: bytes) -> str:
    return " ".join(f"{x:02X}" for x in b)


def float32_word_swapped(angle_deg: float) -> bytes:
    """
    Device expects float32 with 16-bit word swap:
      struct.pack('<f') gives b0 b1 b2 b3 (LE)
      on-wire wants          b2 b3 b0 b1
    """
    b0, b1, b2, b3 = struct.pack("<f", float(angle_deg))
    return bytes([b2, b3, b0, b1])


def build_rotate(angle_deg: float, msg_id: int = ROTATE_ID) -> bytes:
    f = float32_word_swapped(angle_deg)  # 4 bytes
    w0, w1, w2, w3 = f

    return bytes([
        msg_id, ROTATE_OPCODE,
        0x00, 0x00, 0x00, 0x00,
        w0, w1, w2, w3,
        0x00, 0x00,
        msg_id, ROTATE_OPCODE,
        w0, w1
    ])


def send(ser: serial.Serial, payload: bytes, label: str = "") -> None:
    ser.write(payload)
    if label:
        print(f"{label}")
    print(f"TX ({len(payload)}): {hexdump(payload)}")


def ask(prompt: str) -> str:
    return input(prompt).strip()


def pick_mode() -> str:
    while True:
        print("\nMode: (R)otate, (L)ight on, (Q)uit")
        c = ask("> ").lower()
        if c in ("r", "l", "q"):
            return c


def pick_direction() -> str:
    while True:
        print("\nDirection: (1) CW, (2) CCW, (B)ack")
        c = ask("> ").lower()
        if c == "1":
            return "CW"
        if c == "2":
            return "CCW"
        if c == "b":
            return "BACK"


def pick_angle() -> float | None:
    while True:
        opts = "  ".join([f"({i+1}) {a}°" for i, a in enumerate(COMMON_ANGLES)])
        print(f"\nAngle: {opts}   (A)rbitrary   (B)ack")
        c = ask("> ").lower()

        if c == "b":
            return None

        if c == "a":
            v = ask("Enter degrees (e.g. 22.5) > ").strip()
            try:
                return float(v)
            except ValueError:
                print("Not a number.")
                continue

        # preset by number
        if c.isdigit():
            idx = int(c) - 1
            if 0 <= idx < len(COMMON_ANGLES):
                return float(COMMON_ANGLES[idx])

        print("Invalid choice.")


def main():
    port = sys.argv[1] if len(sys.argv) > 1 else PORT_DEFAULT

    print(f"Opening {port} @ {BAUD}...")
    with serial.Serial(
        port=port,
        baudrate=BAUD,
        bytesize=serial.EIGHTBITS,
        parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        timeout=0,
    ) as ser:

        while True:
            mode = pick_mode()

            if mode == "q":
                print("Bye.")
                return

            if mode == "l":
                send(ser, LIGHT_ON, "Light On")
                continue

            # mode == "r"
            direction = pick_direction()
            if direction == "BACK":
                continue

            angle = pick_angle()
            if angle is None:
                continue

            if direction == "CCW" and angle > 0:
                angle = -angle

            pkt = build_rotate(angle)
            send(ser, pkt, f"Rotate {direction} {abs(angle)}°")


if __name__ == "__main__":
    main()