keybrd/src/PortMCP23S17.h

#ifndef PORTMCP23S17_H
#define PORTMCP23S17_H
#include <Arduino.h>
#include <inttypes.h>
#include <SPI.h>
#include <PortIOE.h>
#include <PortInterface.h>

/*
readPins are connected to matrix col
write pin is connected to matrix Row (strobe pin) or LED.

Slave Select is hardcoded to Arduino Pin 10.
Arduino Pin 10 avoids the speed penalty of digitalWrite.

Instantiation
 ------------
readPins parameter is configures port's pins.
Example instantiation:
    const uint8_t PortIOE::DEVICE_ADDR = 0x20;  //MCP23S17 address, all 3 ADDR pins are grounded

    PortIOE port_B(1);
    Port_MCP23S17 portWrite_B(port_B, 0);       //all pins are set to output for strobes and LEDs

    PortIOE port_A(0);
    Port_MCP23S17 portRead_A(port_A, 1<<0 | 1<<1 ); //pins 0,1 are set to input for reading,
                                                    //remaining pins can be used for LEDs

Diode orientation
 ----------------
Diode orientation is explained in keybrd_library_user_guide.md > Diode orientation

MCP23S17 data sheet
 ------------------
 http://www.onsemi.com/pub_link/Collateral/MCP23S17-D.PDF
*/
class PortMCP23S17 : public PortInterface
{
    private:
        PortIOE& port;
        const uint8_t readPins;                 //bits, IODIR 0=output, 1=input
        uint8_t transfer(const uint8_t command, const uint8_t registerAddr, const uint8_t data);
    public:
        PortMCP23S17(PortIOE& port, const uint8_t readPins) : port(port), readPins(readPins) {}
        void begin(const uint8_t strobeOn);
        virtual void write(const uint8_t pin, const bool logicLevel);
        virtual uint8_t read();
};
#endif