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theoctal / octalbonescript

A more stable, continuously tested and better node.js library for scripting your BeagleBone
MIT License
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How can I use GPIO pins and UART4? #81

Closed maxwellhadley closed 6 years ago

maxwellhadley commented 7 years ago

I'm using a BBB, with an 18 month old OS:

uname - a
Linux redbox 4.1.18-ti-r53 #1 SMP Thu Mar 17 19:41:05 UTC 2016 armv7l GNU/Linux
node --version

v6.11.3

I have modified /etc/default/capemgr to load BB-UART4 so I can use /dev/ttyO4 from serialport:

CAPE=BB-UART4

I'm using octalbonescript from Node-RED & the supplied Beaglebone nodes. If I set the environment variable AUTO_LOAD_CAPE=0 then I can use /dev/ttyO4, but all GPIO pins are 'not available':

VError: The pin P9_42 is not availble to write. Please make sure it is not used by another cape.

If I run without the environment variable, then I get the 'file already exists' error #65. If I remove the line from /etc/default/capemgr that loads BB-UART4 and run without the environment variable, I can access the pins but not /dev/ttyO4.

How can I access both GPIO pins and UART4 from the same application?

maxwellhadley commented 7 years ago

I found a workaround. First, install an up-to-date bb-cape-overlays:

sudo apt-get install bb-cape-overlays

Then, change /etc/default/capemgr to load the appropriate universal cape:

CAPE=cape-universaln

After rebooting, you should see the device file for UART4, /dev/ttyO4, is now present. Next, use the config-pin script (which should have been installed by bb-cape-overlays) to set the pinmux to route the UART TxD & RxD to the appropriate pins:

sudo config-pin P9_11 uart
sudo config-pin P9_13 uart

(If this step is missing, you can happily open /dev/ttyO4 and use it without errors, but the signals never get off the chip - it took me hours to work this bit out!)

Finally, I run my Node application (Node-RED) startup script with the appropriate environment variable set to let octalbonescript know a universal cape is already loaded. This is necessary because you have to load the universal cape before you can use config-pin to control the pinmux:

AUTO_LOAD_CAPE=0 node-red-pi

This script starts up Node-RED in low-memory mode, which in turn loads octalbonescript to access GPIO pins, and serialport to access UART4. Which it does, successfully. I have added my user account to the gpio group so I don't need to be root to access the GPIO pins

adityapatadia commented 6 years ago

This library is abandoned. Please check notice in README for further information.