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// picoExtension.js
// Shane M. Clements, February 2014
// PicoBoard Scratch Extension
//
// This is an extension for development and testing of the Scratch Javascript Extension API.
(function(ext) {
var device = null;
var rawData = null;
// Sensor states:
var channels = {
slider: 7,
light: 5,
sound: 6,
button: 3,
'resistance-A': 4,
'resistance-B': 2,
'resistance-C': 1,
'resistance-D': 0
};
var inputs = {
slider: 0,
light: 0,
sound: 0,
button: 0,
'resistance-A': 0,
'resistance-B': 0,
'resistance-C': 0,
'resistance-D': 0
};
ext.resetAll = function(){};
// Hats / triggers
ext.whenSensorConnected = function(which) {
return getSensorPressed(which);
};
ext.whenSensorPass = function(which, sign, level) {
if (sign == '<') return getSensor(which) < level;
return getSensor(which) > level;
};
// Reporters
ext.sensorPressed = function(which) {
return getSensorPressed(which);
};
ext.sensor = function(which) { return getSensor(which); };
// Private logic
function getSensorPressed(which) {
if (device == null) return false;
if (which == 'button pressed' && getSensor('button') < 1) return true;
if (which == 'A connected' && getSensor('resistance-A') < 10) return true;
if (which == 'B connected' && getSensor('resistance-B') < 10) return true;
if (which == 'C connected' && getSensor('resistance-C') < 10) return true;
if (which == 'D connected' && getSensor('resistance-D') < 10) return true;
return false;
}
function getSensor(which) {
return inputs[which];
}
var inputArray = [];
function processData() {
var bytes = new Uint8Array(rawData);
inputArray[15] = 0;
// TODO: make this robust against misaligned packets.
// Right now there's no guarantee that our 18 bytes start at the beginning of a message.
// Maybe we should treat the data as a stream of 2-byte packets instead of 18-byte packets.
// That way we could just check the high bit of each byte to verify that we're aligned.
for(var i=0; i<9; ++i) {
var hb = bytes[i*2] & 127;
var channel = hb >> 3;
var lb = bytes[i*2+1] & 127;
inputArray[channel] = ((hb & 7) << 7) + lb;
}
if (watchdog && (inputArray[15] == 0x04)) {
// Seems to be a valid PicoBoard.
clearTimeout(watchdog);
watchdog = null;
}
for(var name in inputs) {
var v = inputArray[channels[name]];
if(name == 'light') {
v = (v < 25) ? 100 - v : Math.round((1023 - v) * (75 / 998));
}
else if(name == 'sound') {
//empirically tested noise sensor floor
v = Math.max(0, v - 18)
v = (v < 50) ? v / 2 :
//noise ceiling
25 + Math.min(75, Math.round((v - 50) * (75 / 580)));
}
else {
v = (100 * v) / 1023;
}
inputs[name] = v;
}
//console.log(inputs);
rawData = null;
}
function appendBuffer( buffer1, buffer2 ) {
var tmp = new Uint8Array( buffer1.byteLength + buffer2.byteLength );
tmp.set( new Uint8Array( buffer1 ), 0 );
tmp.set( new Uint8Array( buffer2 ), buffer1.byteLength );
return tmp.buffer;
}
// Extension API interactions
var potentialDevices = [];
ext._deviceConnected = function(dev) {
potentialDevices.push(dev);
if (!device) {
tryNextDevice();
}
}
var poller = null;
var watchdog = null;
function tryNextDevice() {
// If potentialDevices is empty, device will be undefined.
// That will get us back here next time a device is connected.
device = potentialDevices.shift();
if (!device) return;
device.open({ stopBits: 0, bitRate: 38400, ctsFlowControl: 0 });
device.set_receive_handler(function(data) {
//console.log('Received: ' + data.byteLength);
if(!rawData || rawData.byteLength == 18) rawData = new Uint8Array(data);
else rawData = appendBuffer(rawData, data);
if(rawData.byteLength >= 18) {
//console.log(rawData);
processData();
//device.send(pingCmd.buffer);
}
});
// Tell the PicoBoard to send a input data every 50ms
var pingCmd = new Uint8Array(1);
pingCmd[0] = 1;
poller = setInterval(function() {
device.send(pingCmd.buffer);
}, 50);
watchdog = setTimeout(function() {
// This device didn't get good data in time, so give up on it. Clean up and then move on.
// If we get good data then we'll terminate this watchdog.
clearInterval(poller);
poller = null;
device.set_receive_handler(null);
device.close();
device = null;
tryNextDevice();
}, 250);
};
ext._deviceRemoved = function(dev) {
if(device != dev) return;
if(poller) poller = clearInterval(poller);
device = null;
};
ext._shutdown = function() {
if(device) device.close();
if(poller) poller = clearInterval(poller);
device = null;
};
ext._getStatus = function() {
if(!device) return {status: 1, msg: 'PicoBoard disconnected'};
if(watchdog) return {status: 1, msg: 'Probing for PicoBoard'};
return {status: 2, msg: 'PicoBoard connected'};
}
var descriptor = {
blocks: [
['h', 'when %m.booleanSensor', 'whenSensorConnected', 'button pressed'],
['h', 'when %m.sensor %m.lessMore %n', 'whenSensorPass', 'slider', '>', 50],
['b', 'sensor %m.booleanSensor?', 'sensorPressed', 'button pressed'],
['r', '%m.sensor sensor value', 'sensor', 'slider']
],
menus: {
booleanSensor: ['button pressed', 'A connected', 'B connected', 'C connected', 'D connected'],
sensor: ['slider', 'light', 'sound', 'resistance-A', 'resistance-B', 'resistance-C', 'resistance-D'],
lessMore: ['>', '<']
},
url: '/info/help/studio/tips/ext/PicoBoard/'
};
ScratchExtensions.register('PicoBoard', descriptor, ext, {type: 'serial'});
})({});