Beaglebone Black/Bacon Cape i2c issue

I have set up a Beaglebone Black with the latest Debian download. A circuitco Bacon Cape is mounted.

I am attempting to read the 3-axis accelerometer data via i2c (p9_19,20) using existing code downloaded from baconcapelabs (see code below):

var b = require(‘bonescript’); // Read BoneScript library

var port = ‘/dev/i2c-2’;

var address = 0x1c;

b.i2cOpen(port, address, {}, onI2C); // Open I2C port

b.i2cWriteBytes(port, 0x2a, [0x00]); // Set STANDBY mode

b.i2cWriteBytes(port, 0x0e, [0x00]); // Set scale to 2G

b.i2cWriteBytes(port, 0x2a, [0x01]); // Set ACTIVE mode

setInterval(readA, 200); // Call readA() every 200ms

function onI2C() {


function readA() {

b.i2cReadBytes(port, 1, 6, onReadBytes);


function onReadBytes(x) {

if(x.event == ‘callback’) { var X = convertToG(x.res[0]); // First byte is X

var Y = convertToG(x.res[2]); // Third byte is Y

var Z = convertToG(x.res[4]); // Fifth byte is Z

console.log('X: ’ + X + ’ Y: ’ + Y + ’ Z: ’ + Z);



function convertToG(x) {

if(x >= 128) x = -((x^0xFF)+1); // Get two’s complement

x = x / 64; // Scale to G

x = x.toFixed(2); // Limit decimal places



When I run this javascript code on Cloud9 IDE, I receive the following error:


if (m.ports[args.port[0]].path) path = m.ports[args.port[0]].path;


TypeError: Cannot read property ‘path’ of undefined

at Object.m.doOpen (/usr/local/lib/node_modules/bonescript/src/iic.js:15:30)

at Object.newFunction [as i2cOpen] (/usr/local/lib/node_modules/bonescript/src/my.js:451:31)

at Object. (/var/lib/cloud9/examples/BBB_Accelerometer.js:7:3)

at Module._compile (module.js:577:32)

at Object.Module._extensions…js (module.js:586:10)

at Module.load (module.js:494:32)

at tryModuleLoad (module.js:453:12)

at Function.Module._load (module.js:445:3)

at Timeout.Module.runMain [as _onTimeout] (module.js:611:10)

at ontimeout (timers.js:386:11)

at tryOnTimeout (timers.js:250:5)

at Timer.listOnTimeout (timers.js:214:5)

Changing the i2c channel to i2c-1 allows me to get past this error (had seen that bonescript naming scheme different); however, “x.event” is now undefined upon function onReadBytes.

SSH over USB using i2c tools indicates i2c2 acting as expected.

Any help would be much appreciated.