Scans a button matrix of an old Internet radio. Only for debugging.

mcp23017_scan_matrix.py

import wiringpi

pin_base = 65
i2c_addr = 0x20
#pins = [65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80]
ROWS = range(68, 68 + 4)

def initialize():
        # Set all out pins to 0 (prevent floating)
        for pin in ROWS:
                wiringpi.pinMode(pin,1)
                wiringpi.digitalWrite(pin,0)
        # Set pins for input
        for pin in range(65, 65 + 3):
                wiringpi.pinMode(pin, 0)
        
def scan(row):
        # Out high on current row
        wiringpi.digitalWrite(row, 1)
        # Scan columns
        for col in range(65, 68):
                in_val = wiringpi.digitalRead(col)
                if in_val:
                        print("[{},{}] pressed".format(row, col))       
        wiringpi.digitalWrite(row, 0)


wiringpi.wiringPiSetup()
wiringpi.mcp23017Setup(pin_base,i2c_addr)

# Set all out pins to 0 (prevent floating)
for pin in range(65,81):
        wiringpi.pinMode(pin,1)
        wiringpi.digitalWrite(pin,0)

initialize()

for i in range(100):
        for r in ROWS:
                scan(r)
        wiringpi.delay(200)