BeagleBone-SPI-UART

Enables SPI and UART (serial tty*) hardware ports on the BeagleBone Black.

How to use

On the BeagleBone Black, the SPI ports are both disabled by default, and only the UART0 serial port is accessible via dedicated headers. To easily bypass these limitations, you can use this library in your project, or configure the ports beforehand via the command line interface.

$ node BBIO.js --enable-spi 0
$ node BBIO.js --enable-uart 5

or

var BBIO = require("./BBIO.js");
BBIO.SPI.enable(0, function(){});
BBIO.UART.enable(5, function(){});

API

• BBIO.SPI.enable(index, callback)

Enables the SPI ports on the BeagleBone Black. The index parameter specifies the SPI port to enable. Can be either 0 or 1 (there are only two SPI ports on the BeagleBone Black). Caveat: the HDMI port is inaccessible while the SPI1 is enabled. Be careful! The callback function is invoked after the SPI port is enabled.

• BBIO.UART.enable(index, callback)

Enables the UART (serial tty*) ports on the BeagleBone Black. The index parameter specifies the UART port to enable. Can be either 1, 2, 4 or 5 (port 0 is enabled by default and has a dedicated header, while port 3 is sort of irrelevant as it can't receive data). The callback function is invoked after the UART port is enabled.

Activate SPI or UART on boot

As of kernel 3.8.13-r23a.17 the SPI or UART overlays can be automatically activated during system startup, if you already enabled them at least once. There is a special uEnv.txt on the boot partition that specifies the user environment setup, with the initial content of optargs=quiet drm.debug=7. To access it:

$ if [ ! -d /mnt/boot ]; then mkdir /mnt/boot; fi
$ mount /dev/mmcblk0p1 /mnt/boot
$ nano /mnt/boot/uEnv.txt

For example, to enable both SPI ports on boot, change the file contents to the following:

optargs=quiet drm.debug=7 capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN capemgr.enable_partno=BB-SPI1-01,BB-SPI0-01

Caveat: the HDMI port is inaccessible while the SPI1 is enabled. Be careful!