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probable fix for PWM udev delay #173

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merged 1 commit into from
Jun 8, 2018
Merged

probable fix for PWM udev delay #173

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72 changes: 49 additions & 23 deletions src/hw_mainline.js
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
var fs = require('fs');
var async = require('async');
var my = require('./my');
var parse = require('./parse');
var eeprom = require('./eeprom');
Expand Down Expand Up @@ -314,34 +315,59 @@ var writePWMFreqAndValue = function (pin, pwm, freq, value, resp, callback) {
fs.writeFileSync(path + '/period', period);
}
} else {
try {
if (debug) winston.debug('Stopping PWM');
fs.writeFileSync(path + '/enable', "0\n");
} catch (ex2) {
if (debug) winston.debug('Error stopping PWM: ' + ex2);
}
// It appears that the first time you set the pwm you have to
// set the period before you set the duty_cycle
if (!disablePWM) { //if duty||frequency == 0 do not re-enable PWM (to avoid spikes)
var tryAgain = true;
var tries = 0;

async.until(function () { //try accessing 'path/enable' until no EACCES error is thrown (max 10 times)
return !tryAgain; //to account for udev delay
}, stopPWM, updatePeriodAndDuty); //async.until(test,iteratee,callback)

function stopPWM(callback) {
try {
if (debug) winston.debug('Updating PWM period: ' + period);
fs.writeFileSync(path + '/period', period + "\n");
if (debug) winston.debug('Stopping PWM');
fs.writeFileSync(path + '/enable', "0\n");
callback(null); //if no error
tryAgain = false; //do not try again
} catch (ex2) {
winston.info('Unable to update PWM period, period is set to ' +
currentPeriod +
"\tIs other half of PWM enabled?");
if (debug) winston.debug('Error stopping PWM: ' + ex2);
if (ex2.code == 'EACCES') {
tries++;
if (tries < 10)
tryAgain = true; //if EACCES error thrown try again for a maximum of 10 times
else
tryAgain = false;
callback(null); //async.until requires an err first format callback &
} else { //if there is an error iteration stops, so neglect the error if EACCES thrown
tryAgain = false;
callback(ex2);
}
}
try {
if (debug) winston.debug('Starting PWM');
fs.writeFileSync(path + '/enable', "1\n");
} catch (ex2) {
if (debug) winston.debug('Error starting PWM: ' + ex2);
}

function updatePeriodAndDuty() {
// It appears that the first time you set the pwm you have to
// set the period before you set the duty_cycle
if (!disablePWM) { //if duty||frequency == 0 do not re-enable PWM (to avoid spikes)
try {
if (debug) winston.debug('Updating PWM period: ' + period);
fs.writeFileSync(path + '/period', period + "\n");
} catch (ex2) {
winston.info('Unable to update PWM period, period is set to ' +
currentPeriod +
"\tIs other half of PWM enabled?");
}
try {
if (debug) winston.debug('Starting PWM');
fs.writeFileSync(path + '/enable', "1\n");
} catch (ex2) {
if (debug) winston.debug('Error starting PWM: ' + ex2);
}
}
if (debug) winston.debug('Updating PWM duty: ' + duty);
//if(duty == 0) winston.error('Updating PWM duty: ' + duty);
if (!disablePWM)
fs.writeFileSync(path + '/duty_cycle', duty + "\n");
}
if (debug) winston.debug('Updating PWM duty: ' + duty);
//if(duty == 0) winston.error('Updating PWM duty: ' + duty);
if (!disablePWM)
fs.writeFileSync(path + '/duty_cycle', duty + "\n");
}
} catch (ex) {
resp.err = 'error updating PWM freq and value: ' + path + ', ' + ex;
Expand Down