How to check rs232 port in imx8-8x baseboard in imx8qxp-mek

[yibhan]

Hi guys,

I have a problem to check rs232 port in 8x base board in imx8qxp-mek,  i think uart2 port doesn't work.

I have check already rs232 device in PC environment worked, but in imx8qxp-mek, I have check all of LPUART* ports, but except LPUART0(debug port), 3 lpuart have on received rx data.

I checked dts file i think it is okay.

I have check /unitest/UART/test program and 

cat /proc/tty/driver/fsl-lpuart.

Could let me know where I miss ?

Thank you for reading.

[yibhan]

sorry,

missed preview mail: 

3 lpuart have on received rx data.

-> 3 lpuart have no received rx data.

[joanxie]

did you use nxp board or customized board？B0 or C0? what bsp version do you use？could you share your modification with me?

[yibhan]

Hi guys,

Thank you for answering.

1. I am using imx8qxp-mek evaluation board(CPU) and imx8x baseboard.

2. CPU is C0.

3. bsp verson is kernel 4.14.98-2.3.0

4. I didn't do any modification.

I am using rs232 port in imx8x BB. I want to know How to use this rs232 port.

I have checked "ttyLP2", but it didn't work.

[BiyongSUN]

The  ttyLP2  is enabled  by default BSP.  You can test it. 

The hardware for ttyLP2 is on the base board as J37(DB9 connector). 

1. use stty configure the ttyLP2 and test 

stty -F /dev/ttyLP2 115200
echo abc > /dev/ttyLP2

2. enable ttyLP2 in systemd as another login console for test purpose

systemctl enable serial-getty@ttyLP2

You will have two login consoles. 

[yibhan]

hi biyong sun,

Thank you for answering,

I have followed your comments, but I have setup baudrate and com port, received port have shown always broken input charaters.

I have checked the baudrate and other settings. Where should i check other things?

Thanks,

[yibhan]

Hi BiyongSun,

Thank you for answering,

I can't fully understand your answer, you mean i can check ttyLP2 port without connect rs232 device or should i connect rs232 device?

but, in both of case, I can't see any of charaters in COM10(default serial port in my PC)/11/12/13.

By the way, I have another question,

If i will connect and comunicate UART device, how do i connect my UART device to Base board?

Thanks

[BiyongSUN]

The hardware for ttyLP2 is on the base board as J37(DB9 connector). 

you need a usb to  uart DB9 to connect the J37(DB9 connector).

[yibhan]

Hi Biyong Sun

Thank you  for answering,

By the way, J37 is for RX232, do you mean I should connect to RX232_UART3_RX & TX after MAX3232EETE?

[BiyongSUN]

you need usb to RS232 convertor.  usb side connect to the PC and the DB9 side to the J37.

[yibhan]

Hi BiyongSun,

For your information, I have checked my rs232 device in PC and it works before.

So, it is weird. Should I change RX/TX or something other?

[yibhan]

Hi BiyongSun,

Thank you for answering.

I can't fully understand your answer. you mean i can check ttyLP2 without connect rs232 device?

As you recommend, I have set "

systemctl enable serial-getty@ttyLP2", but doesn't seem to work.

I have com port is COM10/11/12/13 and serial debug port is COM10, but other com port not show any character after input "echo abc > ttyLP2"

[yibhan]

Hi Joanxie,

Could let me guide about how to use UARTx in imx8qxp-mek board?

I am not sure how to check UARTx for my purpose, actually I am no good at checking UARTs

Thanks,