#include "RowScanner_SPIShiftRegisters.h"

void RowScanner_SPIShiftRegisters::begin()
{
    //configure row
    pinMode(STROBE_PIN, OUTPUT);

    //todo there is only one slave, is select needed?
    pinMode (SHIFT_LOAD, OUTPUT);
    digitalWrite (SHIFT_LOAD, HIGH);
}

/*
Sets rowEnd and returns rowState.
*/
read_pins_t RowScanner_SPIShiftRegisters::scan(read_pins_mask_t& rowEnd)
{
    read_pins_t rowState = 0;

    //strobe row on
    digitalWrite(STROBE_PIN, LOW);
    delayMicroseconds(3);                       //time to stablize voltage

    //read all the column pins
    digitalWrite(SHIFT_LOAD, LOW);                      //load parallel inputs to the register
    digitalWrite(SHIFT_LOAD, HIGH);                     //shift the data toward a serial output
    SPI.transfer(&rowState, BYTE_COUNT);

    //strobe row off
    digitalWrite(STROBE_PIN, HIGH);

    rowEnd = 1 << KEY_COUNT;
    return rowState;
}