Friday, January 26, 2018

Beaglebone Black - UART

Beaglebone black has one UART connection pinout. It can be used for uart console communication or normal uart function.
The pinout is purely RX and TX, no CTS and RTS pin for hardware flow control. Typically usage for serial console as standard baud rate is 115200.

UART is simple protocol and simple connection, no clock, one direction.
Picture from wiki page.

To read from Beaglebone, a simple tap to TX pin is suffice.

I connect one probe from LA1002 to the Beaglebone black J1 connector.


Now for the KINGST software settings:


Back to Beaglebone console.
I am using the USB console, instead of uart console. The USB controller is loading USB-CDC driver to emulate USB port as serial port. It will appears as com port in window PC.

By using the USB serial, leave me one unused uart serial communication.

First, checking the device node.
root@beaglebone:~# dmesg | grep tty
[    0.000000] Kernel command line: console=ttyO0,115200n8 capemgr.disable_partno=BB-BONELT-HDMI capemgr.enable_partno=ADAFRUIT-SPI0 root=UUID=06dba3af-499e-44ca-a059-6ee71880bfd0 ro rootfstype=ext4 rootwait coherent_pool=1M quiet init=/lib/systemd/systemd cape_universal=enable
[    0.530794] 44e09000.serial: ttyO0 at MMIO 0x44e09000 (irq = 72) is a OMAP UART0
[    0.542649] console [ttyO0] enabled

The uart device node is ttyO0.

Doing a simple echo to ttyO0.
echo 123 > /dev/ttyO0

From the KINGST VIS, I get this

Took me sometime to get it, after trying to change the KINGST VIS UART configuration.
0x31, 0x32, 0x33, 0x0A - is actually ASCII code. Refer to: http://www.asciitable.com/
Char                HEX
1                      0x31
2                      0x32
3                      0x33
new line          0x0A

haha, I send a normal "hello world"

too bad, the KINGST VIS doesnt have ASCII decoder function.

TO BE CONTINUE ...

I have one Adafruit uart to usb converter. It is pin compatible with Beaglebone Black.
I like module, so easy to use.

Open up one of my favourite terminal software - termite.
Then from Putty console - cat /dev/ttyO0
Testing ... (from PC to Beaglebone)


Testing ... (from Beaglebone to PC)


Will update more if anything interesting come out.

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