Expose bit resolution of ADC, PWM (and others as available)

Signed-off-by: Rick Waldron <[email protected]>

Author: rwaldron

lib/firmata.js

@@ -193,6 +193,7 @@ SYSEX_RESPONSE[QUERY_FIRMWARE] = function(board) {
  */
 
 SYSEX_RESPONSE[CAPABILITY_RESPONSE] = function(board) {
+  var mode, resolution;
   var modes = Object.keys(board.MODES).map(function(key) {
     return board.MODES[key];
   });
@@ -222,7 +223,24 @@ SYSEX_RESPONSE[CAPABILITY_RESPONSE] = function(board) {
         continue;
       }
       if (n === 0) {
-        capability |= (1 << board.currentBuffer[i]);
+        mode = board.currentBuffer[i];
+        resolution = (1 << board.currentBuffer[i + 1]) - 1;
+        capability |= (1 << mode);
+
+        // ADC Resolution of Analog Inputs
+        if (mode === board.MODES.ANALOG && board.RESOLUTION.ADC === null) {
+          board.RESOLUTION.ADC = resolution;
+        }
+
+        // PWM Resolution of PWM Outputs
+        if (mode === board.MODES.PWM && board.RESOLUTION.PWM === null) {
+          board.RESOLUTION.PWM = resolution;
+        }
+
+        // DAC Resolution of DAC Outputs
+        // if (mode === board.MODES.DAC && board.RESOLUTION.DAC === null) {
+        //   board.RESOLUTION.DAC = resolution;
+        // }
       }
       n ^= 1;
     }
@@ -505,6 +523,12 @@ function Board(port, options, callback) {
     RES_TX3: 0x07,
   };
 
+  this.RESOLUTION = {
+    ADC: null,
+    DAC: null,
+    PWM: null,
+  };
+
   this.HIGH = 1;
   this.LOW = 0;
   this.pins = [];

test/unit/firmata.test.js

@@ -1026,6 +1026,12 @@ describe("Board: lifecycle", function() {
     transport.emit("data", [END_SYSEX]);
   });
 
+  it("board.RESOLUTION.* properties have values via CAPABILITY_RESPONSE", function(done) {
+    assert.equal(board.RESOLUTION.ADC, 1023);
+    assert.equal(board.RESOLUTION.PWM, 255);
+    done();
+  });
+
 
   it("querys analog mappings after capabilities", function(done) {
     //[START_SYSEX, ANALOG_MAPPING_QUERY, END_SYSEX]