- Remember: Attendance on Inkfish
Today, we’re going to get GPIO to work on the dev boards. #
Follow directions here:
- https://github.com/scpcom/sophgo-sg200x-debian
- Boot by plugging into laptop via USB. This gives you a USB eithernet device with an IP assigned by the board. The board is .1 on that subnet.
Blink Script #
debian@duos-1d1d:~$ cat blink.py
#!/usr/bin/env python3
"""Blink an LED on the Milk-V Duo S, J3 header pin 7 (GPIO B18).
Run with sudo: sudo python3 blink.py
Blink rate: 2 Hz (LED on 250 ms, off 250 ms).
"""
import os
import subprocess
import sys
import time
GPIO = 466
SYFS = "/sys/class/gpio"
GPIO_DIR = f"{SYFS}/gpio{GPIO}"
PERIOD_S = 0.5 # 2 Hz -> half period
DUO_PINMUX = "/usr/bin/duo-pinmux"
PIN, FUNC = "B18", "B18"
def shell(cmd):
return subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
def sysfs_write(path, value):
with open(path, "w") as f:
f.write(value)
def setup():
if not os.path.exists(DUO_PINMUX):
print(f"warning: {DUO_PINMUX} not found, skipping pinmux", file=sys.stderr)
else:
r = shell([DUO_PINMUX, "-w", f"{PIN}/{FUNC}"])
print(f"pinmux B18 -> GPIO: rc={r.returncode} {r.stdout.strip()}")
if r.returncode != 0:
raise SystemExit("failed to remux B18 as GPIO (need root?)")
if not os.path.exists(f"{GPIO_DIR}/direction"):
sysfs_write(f"{SYFS}/export", str(GPIO))
print(f"exported gpio{GPIO}")
sysfs_write(f"{GPIO_DIR}/direction", "out")
sysfs_write(f"{GPIO_DIR}/value", "0")
print(f"gpio{GPIO} (B18, J3 pin 7) ready as output")
def cleanup():
try:
sysfs_write(f"{GPIO_DIR}/value", "0")
except OSError:
pass
try:
sysfs_write(f"{SYFS}/unexport", str(GPIO))
except OSError:
pass
print("cleaned up, gpio unexported")
def main():
setup()
try:
print("blinking at 2 Hz (Ctrl+C to stop)...")
while True:
sysfs_write(f"{GPIO_DIR}/value", "1")
time.sleep(PERIOD_S / 2)
sysfs_write(f"{GPIO_DIR}/value", "0")
time.sleep(PERIOD_S / 2)
except KeyboardInterrupt:
pass
finally:
cleanup()
if __name__ == "__main__":
main()
