// ----------------------------------------------------- MCP23017 port expander
void cButtonPE16::begin( uint8_t N, uint8_t addr ) {
// need to know how many active buttons so we can mask off the unused
n = max(N,4);
mask = ( 1 << n ) - 1; // for the buttons
nextCheck = millis() + PERIOD;
sidx = 0;
// configure the port expander
PEaddr = addr;
Wire.beginTransmission( PEaddr );
Wire._WRITE( IOCONZ ); // valid command only if BANK = 0, which is true upon reset
Wire._WRITE( BANK ); // set BANK = 1 if it had been 0 (nothing happens if BANK = 1 already)
Wire.endTransmission();
// now, send our IO control byte with assurance BANK = 1
Wire.beginTransmission( PEaddr );
Wire._WRITE( IOCON );
Wire._WRITE( BANK | SEQOP | DISSLW ); // banked operation, non-sequential addressing
Wire.endTransmission();
// now, set up port B pins for input
Wire.beginTransmission( PEaddr );
Wire._WRITE( IODIRB );
Wire._WRITE( 0x0F ); // configure port B pins: input 0-3, output 4-7
Wire.endTransmission();
// reverse the polarity (so that 0 = not pressed, 1 = pressed)
Wire.beginTransmission( PEaddr );
Wire._WRITE( IPOLB );
Wire._WRITE( 0x0F ); // configure port B polarity: reversed 0-3, normal 4-7
Wire.endTransmission();
ledAllOff(); // all LED's off by default
}
boardIO::boardIO()
{
ledAllOff();
}