I have an application in which I need to transmit data bidirectionally between a 5V microcontroller and Beaglebone Black.
Please provide hints on how to go about accessing UART-4 of BBB and also what would be the easiest way to save the data received by BBB in a txt file.
I’m running Ubuntu-13.04-2013-10-08.img


I did a blog post showing how to use UART4 to talk to an ATmega328p
[1]. My ATmega was at 3.3V though, so you'll need to use logic level
converters (MOSFETs) to convert between your 5V micro and the Beagle,
which operates at 3.3V logic levels. This blog post [2] uses the 5V
version and shows how to use the logic level converters.

If you have a recent debian image, you can enable UART 4 with the
following command:

echo BB-UART4 | sudo tee /sys/devices/bone_capemgr.*/slots

If you don't have the BB-UART4-00A0.dtbo in /lib/firmware, you should
probably upgrade your BBB.

After that command, you should see /dev/ttyO4 appear, which is the UART
you seek.

You may need to change the baud rate of your serial line, do that with
this command:

sudo stty -F /dev/ttyO4 9600

Good luck,




Since BBB is a 32 bit device and the microcontroller is 8 bit, shouldn’t we set the number of data bits in UART frame in BBB to 8 bits?

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