Digispark and nodejs - talking to the Digispark Arduino-compatible microcontroller via USB with the node-hid library

ds-duino.ino

/*
 * Accept control commands via USB.
 * 
 * Commands start with '!' and end with '.'
 * Commands have three parts: action, pin, value: !AAPPVV.
 *
 * E.g. '!01p101.' is DigitalWrite, Pin1, value = 1
 *
 * Note: This is currently *very* crude. Much improvement could be made.
 * I think the use of strncpy is eating a lot of memory. Refactor?
 */

#define START '!'
#define END '.'

#include <DigiUSB.h>

bool debug = false;

int index = 0;

char messageBuffer[12];
char cmd[3];
char pin[3];
char val[5];

void setup() {
  pinMode(1, OUTPUT);
  // Blink three times to signal ready.
  for(index = 0; index < 3; index++) {
    digitalWrite(1, HIGH);
    delay(100);
    digitalWrite(1, LOW);
    delay(100);
  }
  DigiUSB.begin();
}

void loop() {
  if(DigiUSB.available()) {
    char x = DigiUSB.read();
    if (x == START) index = 0;      // start
    else if (x == END) process(); // end
    else messageBuffer[index++] = x;
  }
  DigiUSB.refresh();
  delay(10);
}

/*
 * Deal with a full message and determine function to call
 */
void process() {
  index = 0;

  strncpy(cmd, messageBuffer, 2);
  cmd[2] = '\0';
  strncpy(pin, messageBuffer + 2, 2);
  pin[2] = '\0';

  if (atoi(cmd) > 90) {
    strncpy(val, messageBuffer + 4, 2);
    val[2] = '\0';
  } else {
    strncpy(val, messageBuffer + 4, 3);
    val[4] = '\0';
  }

  if (debug) {
    DigiUSB.println(messageBuffer);
  }

  int cmdid = atoi(cmd);

  DigiUSB.println(cmd);
  DigiUSB.println(pin);
  DigiUSB.println(val);

  switch(cmdid) {
    case 0:  sm(pin,val);              break;
    case 1:  dw(pin,val);              break;
//    case 2:  dr(pin,val);              break;
    case 3:  aw(pin,val);              break;
//    case 4:  ar(pin,val);              break;
    case 99: toggleDebug(val);         break;
    default:                           break;
  }
}

/*
 * Toggle debug mode
 */
void toggleDebug(char *val) {
  if (atoi(val) == 0) {
    debug = false;
    DigiUSB.println("goodbye");
  } else {
    debug = true;
    DigiUSB.println("hello");
  }
}

/*
 * Set pin mode
 */
void sm(char *pin, char *val) {
  if (debug) DigiUSB.println("sm");
  int p = getPin(pin);
  if(p == -1) { if(debug) DigiUSB.println("badpin"); return; }
  if (atoi(val) == 0) {
    pinMode(p, OUTPUT);
  } else {
    pinMode(p, INPUT);
  }
}

/*
 * Digital write
 */
void dw(char *pin, char *val) {
  if (debug) DigiUSB.println("dw");
  int p = getPin(pin);
  if(p == -1) { if(debug) DigiUSB.println("badpin"); return; }
  pinMode(p, OUTPUT);
  if (atoi(val) == 0) {
    digitalWrite(p, LOW);
  } else {
    digitalWrite(p, HIGH);
  }
}

/*
 * Digital read
 */
/*
void dr(char *pin, char *val) {
  if (debug) DigiUSB.println("dr");
  int p = getPin(pin);
  if(p == -1) { if(debug) DigiUSB.println("badpin"); return; }
  pinMode(p, INPUT);
  int oraw = digitalRead(p);
  char m[7];
  sprintf(m, "%02d::%02d", p,oraw);
  DigiUSB.println(m);
}
*/

/*
 * Analog read
 */
/*
void ar(char *pin, char *val) {
  if(debug) DigiUSB.println("ar");
  int p = getPin(pin);
  if(p == -1) { if(debug) DigiUSB.println("badpin"); return; }
  pinMode(p, INPUT); // don't want to sw
  int rval = analogRead(p);
  char m[8];
  sprintf(m, "%s::%03d", pin, rval);
  DigiUSB.println(m);
}
*/
void aw(char *pin, char *val) {
  if(debug) DigiUSB.println("aw");
  int p = getPin(pin);
  pinMode(p, OUTPUT);
  if(p == -1) { if(debug) DigiUSB.println("badpin"); return; }
  analogWrite(p,atoi(val));
}

int getPin(char *pin) { //Converts to P0-P5, and returns -1 on error
  int ret = -1;
  if(pin[0] == 'P' || pin[0] == 'p') {
    switch(pin[1]) {
      case '0':  ret = 0; break;
      case '1':  ret = 1; break;
      case '2':  ret = 2; break;
      case '3':  ret = 3; break;
      case '4':  ret = 4; break;
      case '5':  ret = 5; break;
      default:             break;
    }
  } else {
    ret = atoi(pin);
    if(ret == 0 && (pin[0] != '0' || pin[1] != '0')) {
      ret = -1;
    }
  }
  return ret;
}

ds-node-test.js

var HID = require('./build/Release/HID.node');

var device,ds,char;
var devices = HID.devices(0x16c0, 0x05df); // look for digisparks

if (devices.length > 0) {
  console.log(devices);
	console.log('Attaching to first entry.');
	device = devices[0];
	console.log('USB Path:', device.path);

	ds = new HID.HID(device.path);

	ds.setNonBlocking(1); // blocking is bad, mkay?

	ds.write(new Buffer("!990011.")); // turn debug on

	console.log('analogWrite P1 25...');
	var cmd = "!03p125.";
	// Buffer is an array of bytes, like write() wants.
	ds.write(new Buffer(cmd));


	while (1) {
		var buff = new Buffer(ds.getFeatureReport(0,254));
		console.log("using getFeatureReport: ", buff.toString());
		if (! buff.length) break;
	}

	console.log('analogWrite P0 45...');
	cmd = "!03p245.";
	// Buffer is an array of bytes, like write() wants.
	ds.write(new Buffer(cmd));

//*
	ds.read(function(err, data){
		if (err) {
			console.log("Error! ", err);
		} else {
			console.log("using ds.read: ", data);
		}
	});
//*/
//**/	ds.read(onRead);

} else {
	console.log('No Digispark found.');
}

function onRead(err, data) {
	if(err) {
		console.log('Err! :-(');
	} else {
		if (1 || data.length) {
			console.log('DATA: ' + data);
		}

		ds.read(onRead);
	}
}