Control the SIDBlaster USB (SID chip controller) with Python via the ftdi_sio module

sidblasterserial.py

#!/usr/bin/env python3
"""
SIDBlaster USB - Serial Interface Demo
- Demonstrates reading and writing SID registers via serial port.
- The ftdi_sio module should be loaded and presenting on /dev/ttyUSB0.
- Tested on SIDBlaster-USB Tic Tac on Linux.
- Raspberry Pi should work too.
"""

import time
import serial

def read_sid_register(port, register):
    """Read a value from a SID register."""
    read_command = 0x80 | (1 << 5) | register
    port.write(bytes([read_command]))
    response = port.read(1)
    if len(response) == 1:
        return response[0]
    return None

def write_sid_register(port, register, value):
    """Write a value to a SID register."""
    write_command = 0xC0 | (1 << 5) | register
    port.write(bytes([write_command, value]))
    time.sleep(0.001)

def main():
    "SIDBlaster USB - Serial Interface Demo"
    print(main.__doc__)
    print("=" * len(main.__doc__))

    port = serial.Serial(
        port='/dev/ttyUSB0',
        baudrate=500000,
        bytesize=serial.EIGHTBITS,
        parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        timeout=1
    )

    print(f"Opened {port.name} at {port.baudrate} baud\n")

    # Test 1: Read POTX register
    print("Test 1: Reading POTX register (25)")
    print("-" * 40)
    value = read_sid_register(port, 25)
    if value is not None:
        print(f"✅ Register 25 = 0x{value:02x} ({value})")
        if value == 0xFF:
            print("🎉 Correct! Unconnected paddle reads 0xFF\n")
        else:
            print(f"⚠️  Expected 0xFF but got 0x{value:02x}\n")
    else:
        print("❌ Failed to read register\n")

    # Test 2: Play middle C
    print("Test 2: Playing middle C (261.63 Hz)")
    print("-" * 40)

    middle_c_freq = 261.63
    freq_value = int((middle_c_freq * 16777216) / 1000000)
    freq_low = freq_value & 0xFF
    freq_high = (freq_value >> 8) & 0xFF

    print(f"Frequency value: {freq_value} (0x{freq_value:04x})")
    print(f"  Low byte:  0x{freq_low:02x}")
    print(f"  High byte: 0x{freq_high:02x}")

    print("\nConfiguring SID Voice 1...")
    write_sid_register(port, 0x00, freq_low)    # Frequency low byte
    write_sid_register(port, 0x01, freq_high)   # Frequency high byte
    write_sid_register(port, 0x02, 0x00)        # Pulse width low byte
    write_sid_register(port, 0x03, 0x08)        # Pulse width high byte (50% duty cycle)
    write_sid_register(port, 0x05, 0x09)        # Attack/Decay (fast attack, medium decay)
    write_sid_register(port, 0x06, 0x00)        # Sustain/Release (zero sustain, fast release)
    write_sid_register(port, 0x18, 0x0F)        # Volume to maximum

    print("Playing sawtooth wave for 250ms...")
    write_sid_register(port, 0x04, 0x21)        # Gate on, sawtooth waveform
    time.sleep(0.25)
    write_sid_register(port, 0x04, 0x20)        # Gate off

    time.sleep(0.1)

    print("Playing pulse wave for 250ms...")
    write_sid_register(port, 0x04, 0x41)        # Gate on, pulse waveform
    time.sleep(0.25)
    write_sid_register(port, 0x04, 0x40)        # Gate off

    print("Notes stopped")

    print("\nSilencing SID...")
    write_sid_register(port, 0x18, 0x00)        # Volume to zero

    port.close()
    print("\nDone!")

if __name__ == "__main__":
    main()