UART via Expansion Headers?

Discussion of your EDM baseboard, your add-on boards or other peripherals for your wandboard.

UART via Expansion Headers?

Postby postman » Wed Jan 07, 2015 5:44 pm

Hi all,

I need to interface with a TTL UART-based peripheral and am looking for a more robust/permanent solution than soldering on to TP123/125. Is it possible to route the unused UART (UART2, mxctty1 if I recall correctly) to one of the expansion headers? Has anyone been successful with this?

If not, what is the best way to expose a basic UART (Tx, Rx, Vcc, GND only -- no need for CTS/RTS) to a peripheral?

For record, I am running a Yocto-based 3.10.17-1.0.1 kernel on a Quad.

Thanks for your help!
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Re: UART via Expansion Headers?

Postby JayminD » Thu Jan 08, 2015 4:26 am

Hi Postman,

I had also same issue as you are facing now.
But unfortunately I didn't find any other track or way on expansion header on WB Q.
I also used YOCTO 3.0.35 and WBQ same like you and I also needed another UART for application related, but I only found the test points TP123 and TP125 which for UART2 as you said. :(

But due to soldering and hardware problem I put it on hold right now, :(

Anyhow if any other way will found then I will post here soon.
Same you.
Thanks and Regards
JAYMIN DABHI
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Re: UART via Expansion Headers?

Postby postman » Thu Jan 08, 2015 3:34 pm

Hi JayminD, thanks for your reply. I'll update this thread if I come up with anything on my own.

How does Yocto handle pin muxing in general? Is there a source file that specifies the IC's internal pin routing at compile time, or is that runtime configurable on the IMX6? I hope I'm asking the right question -- this is the first board that I've used Yocto for...
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Re: UART via Expansion Headers?

Postby michael_stt » Mon Jan 12, 2015 12:16 pm

You can access at least one more UART (or via a USB/UART converter, for example) on the card edge connector, but yes, you'd have to create a custom carrier board as we did.
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Re: UART via Expansion Headers?

Postby postman » Mon Jan 12, 2015 3:40 pm

Hi Michael,

By card edge connector, do you mean the large connector that connects the processor board to the carrier/I/O board?

Best,
Matt
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Re: UART via Expansion Headers?

Postby arabella12345 » Sat Mar 14, 2015 10:10 am

Does someone know why it is not possible to use these pins as output?
Can this be an error in my device tree files or is this a "side" effect of using the pins (EIM_DA11 and EIMDA8) also for the boot mode?

Have other people success in using these gpio pins as output?
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Re: UART via Expansion Headers?

Postby jury093 » Sat Mar 14, 2015 10:51 am

arabella12345 wrote:Can this be an error in my device tree files or is this a "side" effect of using the pins (EIM_DA11 and EIMDA8) also for the boot mode?
Have other people success in using these gpio pins as output?

EIM_DA11 is GPIO3_12 (schematic board b1) is number (3-1) * 32 + 12 = 76
after load sytem try:
echo 76 > /sys/class/gpio/export
You should see new file for pin control
ls /sys/class/gpio/gpio76

if return fail for echo command, then this pin is busy another driver (maybe edm.c)
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Re: UART via Expansion Headers?

Postby ttwand » Fri Mar 03, 2017 7:40 am

Hello,

I want to test my communication protocol with serial port.
I have to use wandboard's TP123 and TP125.


in imx6qd-wandboard.dtsi file, there is uart1 and uart3 enabled.

Code: Select all
&uart1 {
   pinctrl-names = "default";
   pinctrl-0 = <&pinctrl_uart1_1>;
   status = "okay";
};

&uart3 {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_uart3_2>;
        fsl,uart-has-rtscts;
        status = "okay";


Can I use directly this pins or what can I do for to use this TestPins?

Thank you. :?:
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