On Mon, Apr 25, 2016 at 10:26 AM, Jean-Sebastien Stoezel <
[email protected]> wrote:

> Hi:
>
> I have a BeagleBone Green running Linux version 4.1.15-ti-rt-r43 and
> Debian 8.3 (Jessie). I am cannot seem to send or receive data on UART2.
>
> What I can see see is that UART2 is enabled:
>
> *[    4.368638] 48024000.serial: ttyS2 at MMIO 0x48024000 (irq = 160,
> base_baud = 3000000) is a 8250).*
>
> I have used minicom, a C++ QT application, and an online script (
> http://jsfiddle.net/AjnJs/67/) to try and send data over UART2 but
> nothing seems to get to the pins.
>
> I feel confident in the hardware I use to verify that no data is sent over
> the UART2 pins (I have yet to get an oscilloscope out though).
>
> Looking at the BBG schematic, it seems the UART2 pins are shared with the
> SPI. I am wondering if by default SPI might be configured, which might
> prevent UART2 from operating.
>
> Has anybody ever gotten UART2 to work on the BBG? If so, what steps did
> you take?
> What software check can I perform to verify UART2 is effectively ready to
> operate?
>

Out of the box, we have it setup to utilize universal io, so to enable ths
uart pinmux:

debian@beaglebone:~$ config-pin -l P9.21
default gpio gpio_pu gpio_pd spi uart i2c pwm
debian@beaglebone:~$ config-pin -l P9.22
default gpio gpio_pu gpio_pd spi uart i2c pwm

debian@beaglebone:~$ config-pin P9.21 uart
debian@beaglebone:~$ config-pin P9.22 uart

debian@beaglebone:~$ config-pin -q P9.21
P9_21 Mode: uart
debian@beaglebone:~$ config-pin -q P9.22
P9_22 Mode: uart

ttyS2 should now be working..

Regards,

-- 
Robert Nelson
https://rcn-ee.com/

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