strange error when running simple *.js filesetting a (GPIO) to output using beaglebone black Rev C.

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1

Hello! How’s everything?

I encountered strange error when running simple *.js file
setting a pin (GPIO) to output using beaglebone black Rev C, which I received this August.

I even reinstalled bonescript using
“npm install -g bonescript”
but still encounter the same error message.

led = “P9_11”, “9_12” worked
led = “P8_39”, “P8_40”, “P8_41”, and many other pins
does not work with error message listed below
following “simpleDigitalOut.js”:

//====================================
//simpleDigitalOut.js

var b = require(’/usr/local/lib/node_modules/bonescript’);

var led = “P8_41”;
b.pinMode(led, b.OUTPUT);

console.log(“end of program”);

//=====================================
root@beaglebone:/var/lib/cloud9/myProg# node simpleDigitalOut.js

/usr/local/lib/node_modules/bonescript/my.js:57
if(slot[0]) {
^
TypeError: Cannot read property ‘0’ of null
at Object.exports.load_dt (/usr/local/lib/node_modules/bonescript/my.js:57:20)
at Object.exports.create_dt (/usr/local/lib/node_modules/bonescript/my.js:123:33)
at Object.exports.setPinMode (/usr/local/lib/node_modules/bonescript/hw_capemgr.js:83:12)
at Object.f.pinMode (/usr/local/lib/node_modules/bonescript/index.js:160:15)
at Object. (/var/lib/cloud9/myProg/simpleDigitalOut.js:4:3)
at Module._compile (module.js:456:26)
at Object.Module._extensions…js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Function.Module.runMain (module.js:497:10)
root@beaglebone:/var/lib/cloud9/myProg#
//=====================================

I googled but cannot find a solution to this problem.

It would be a great help if you can guide me through it.
your advice is very much appreciated.

Many thanks,
Fung Yang

2

Hi, I am guessing here only.
These GPIO are by default reserved for HDMI connection (look-up PIN assignment for beagle bone black). I think you might need to disable HDMI.
See below my `/boot/uEnv.txt to disable HDMI


cat /boot/uEnv.txt

#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0

uname_r=3.8.13-bone68

#dtb=

cmdline=quiet init=/lib/systemd/systemd

##Example

#cape_disable=capemgr.disable_partno=

#cape_enable=capemgr.enable_partno=

##Disable HDMI/eMMC

#cape_disable=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN,BB-BONE-EMMC-2G

##Disable HDMI

cape_disable=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN

##Disable eMMC

#cape_disable=capemgr.disable_partno=BB-BONE-EMMC-2G

##Audio Cape (needs HDMI Audio disabled)

#cape_disable=capemgr.disable_partno=BB-BONELT-HDMI

#cape_enable=capemgr.enable_partno=BB-BONE-AUDI-02

##enable BBB: eMMC Flasher:

#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh