Taking another crack at keyboard matrix scanning using the NRF52 PPI

Hey! Just wanted to post an update, I had a go at implementing the suggestions yesterday evening & got something working - it catches even fast button presses but occasionally drops them which is something I'm looking into. I've attached some code, its still ugly POC code & I'm sure there are things I can do to make it run more efficiently :)

//=======================================================================
// MATRIX
//=======================================================================
const matrix = (rows, cols) => {
  let _scanning;
  let _onStopScanning;
  let _numberOfIdleScansBeforeStop;
  let _numberOfActiveKeys;
  let _numberOfIdleScans;
  let _keyStates;
  let _rowStates;
  let _cols = cols;
  let _rows = rows;
  
  const defaultKeyStates = new Array(_rows.length).fill(new Array(_cols.length).fill(0));
  // const resetKeyStates = () => _keyStates = defaultKeyStates;

  // Make this flexible for different rows/cols
  const resetKeyStates = () => _keyStates = [
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ]
  ];
  // Make this flexible for different rows/cols
  const resetRowStates = () => _rowStates = [ 0, 0, 0, 0 ];
  const resetNumberOfIdleScans = () => _numberOfIdleScans = 0;
  const resetNumberOfActiveKeys = () => _numberOfActiveKeys = 0;
  
  const getMatrixState = () => _keyStates;
  const getKeyState = (row, col) => _keyStates[row][col];
  
  const setPinModes = () => {
    "compiled";
    // @TODO: Can we set an array of pinmodes instead of iterating?
    _rows.forEach(row => pinMode(row, 'output'));
    _cols.forEach(col => pinMode(col, 'input_pulldown'));
  };
  
  const unsetPinModes = () => {
    "compiled";
    _rows.forEach(row => pinMode(row, 'input_pulldown'));
    _cols.forEach(col => pinMode(col, 'output'));
  };
  
  const setup = () => {
    "compiled";
    resetNumberOfIdleScans();
    resetNumberOfActiveKeys();
    resetKeyStates();
    resetRowStates(); 
  };

  const startScanning = (onChange, onStop, numberOfIdleScansBeforeStop, interval) => {
    "compiled";
    console.log("======================");
    setPinModes();
    _numberOfIdleScansBeforeStop = numberOfIdleScansBeforeStop;
    _onStopScanning = onStop;
    if (!_scanning) _scanning = setInterval(() => scanMatrix(onChange), interval || 1);
  };
  const stopScanning = () => {
    "compiled";
    resetNumberOfIdleScans();
    resetNumberOfActiveKeys();
    resetKeyStates();
    resetRowStates();
    unsetPinModes();
    if (_scanning) { clearInterval(_scanning); _scanning = undefined; }
    if (_onStopScanning) _onStopScanning();
  };
  const isScanning = () => !!_scanning;
  
  const updateNumberOfIdleScans = (activeKeys, callback) => {
    "compiled";
    if (activeKeys === 0) _numberOfIdleScans = _numberOfIdleScans + 1;
    callback();
  };
  const stopOnIdle = () => {
    "compiled";
    if (_numberOfIdleScansBeforeStop && (_numberOfIdleScans >= _numberOfIdleScansBeforeStop)) stopScanning();
  };
  
  const updateNumberOfActiveKeys = (isActive) => {
    "compiled";
    if (isActive) {_numberOfActiveKeys = _numberOfActiveKeys + 1;}
    else if (_numberOfActiveKeys > 0) {_numberOfActiveKeys = _numberOfActiveKeys - 1;}
  };

  const parseRowToString = (row) => {
    "compiled";
    return row.toString(2);
  };

  const detectChange = (rowState, currentRowIndex, onChange) => {
    "compiled";
    if (rowState !== _rowStates[currentRowIndex]) {
      _rowStates[currentRowIndex] = rowState;
      const parsedRow = parseRowToString(rowState);

      // @TODO: This feels inefficient
      for (let colIndex = 0; colIndex < parsedRow.length; colIndex++) {
        const col = Number(parsedRow[colIndex]);
        if (col !== _keyStates[currentRowIndex][colIndex]) {
          _keyStates[currentRowIndex][colIndex] = col;
          onChange(currentRowIndex, colIndex, col);
          updateNumberOfActiveKeys(col);
        }
      }
      
      
    }
  };

  const scanMatrix = (onChange) => {
    "compiled";
    _rows.forEach((currentRow, currentRowIndex) => {
      digitalWrite(currentRow, 1);

      detectChange(digitalRead(_cols), currentRowIndex, onChange);

      digitalWrite(currentRow, 0);
    });
    updateNumberOfIdleScans(_numberOfActiveKeys, stopOnIdle);
  };
  
  setup();

  return {
    getMatrixState: getMatrixState,
    getKeyState: getKeyState,
    startScanning: startScanning,
    stopScanning: stopScanning,
    isScanning: isScanning
  };
};































//=======================================================================
// USAGE
//=======================================================================
const ROWS = [D14, D15, D17, D30];
const COLS = [D16, D18, D19, D20, D22, D25, D26, D27, D28, D29, D31];

let _rowWatchers;

const myMatrix = matrix(ROWS, COLS);

const onMatrixChange = (currentRow, currentCol, isActive) => {
  // Keep track of key press/release duration
  // Classify as tap or hold
  
  // keyPress when a key is pressed, payload containing key row/column
  // keyRelease when a key is released, payload containing row/column, duration of press
  // keyTap when a key press/release cycle is < 200ms, payload containing row/column
  // keyHoldStart when a key has been pressed for > 200ms, payload containing row/column
  // keyHoldEnd fired when held key is released, payload containing row/column, duration of press
  console.log(currentRow, currentCol, isActive);
};

const onMatrixStop = () => {
  "compiled";
  enable();
};

const handleWatchTrigger = (e) => { 
  "compiled";
  unsetWatches(_rowWatchers);
  setColsLow(COLS);
  myMatrix.startScanning(onMatrixChange, onMatrixStop, 2, 1);
};

const setColsHigh = (cols) => {
  "compiled";
  cols.forEach(col => digitalWrite(col, 1));
};
const setColsLow = (cols) => {
  "compiled";
  cols.forEach(col => digitalWrite(col, 0));
};
const setWatches = (rows) => {
  "compiled";
  _rowWatchers = rows.map(row => setWatch((e) => handleWatchTrigger(e), row, { repeat:false, edge:'rising', debounce: 10 }));
};

// @TODO: Make this more resilient, this errors when it can't clear a watch
const unsetWatches = (rowWatchers) => {
  "compiled";
  rowWatchers.forEach(rowWatcher => clearWatch(rowWatcher));
};

const enable = () => {
  "compiled";
  ROWS.forEach(row => pinMode(row, 'input_pulldown'));
  COLS.forEach(col => pinMode(col, 'output'));
  setColsHigh(COLS);
  setWatches(ROWS);
};

enable();