Test UART using GPIO

RE: Test UART using GPIO

cbd — Thu, 23 Aug 2018 06:47:21 GMT

Agreed.

If you're using the GPIO lines to the interface MCU for your lead connection then you'll have issues, especially if your still using the USB port on the other side for debug.

I believe that there's a note that this shouldn't be done for fear of damaging the interface MCU.

RE: Test UART using GPIO

Marjeris Romero — Wed, 22 Aug 2018 16:37:22 GMT

So if I understand correctly, you want to connect the GPIO pins used for UART on the nRF52840 directly to a USB-RS232 serial converter cable (i.e. Digi-Key part # 768-1065-ND)?

Try first to connect USB-RS232 ground to any GND pin on the nrf52840 DK. You may also need to disconnect the interface MCU by switching SW6 to nRF ONLY or set other GPIO pins as UART RX/TX in software.

RE: Test UART using GPIO

Sridhar Jonnavittula — Wed, 22 Aug 2018 09:33:20 GMT

When I connect to J2 it is working fine with same COM port settings. But there may be cases where using GPIO on DK and USB-RS232 converter both as a combination is a requirement right. How to support this requirement.

RE: Test UART using GPIO

Marjeris Romero — Wed, 22 Aug 2018 08:56:54 GMT

The UART signals are routed through the interface MCU, can you try connecting your micro USB cable to the J2 connector instead?

If you are still having issues, could you please upload a picture or drawing of your setup so we can try to reproduce it?

RE: Test UART using GPIO

Sridhar Jonnavittula — Wed, 22 Aug 2018 08:20:45 GMT

Yes. I have used latest SDK V15.0.0 only and kept same settings for COM port

RE: Test UART using GPIO

Marjeris Romero — Wed, 22 Aug 2018 08:17:50 GMT

Hi,

Which version of the SDK are you using? Have you checked the information in the infocenter for which settings you need to use to test the example? For instance for the newest SDK you should take a look at this page.

Regards,

Marjeris

RE: Test UART using GPIO

Sridhar Jonnavittula — Wed, 22 Aug 2018 07:48:20 GMT

1. I did not connect USB-RS232 ground pin 5 to any of GND pin on nrf52840 DK

2. Yes

and example application don't have Data and Stop bits. Where to set those values?

4. Yes

Is it OK to connect micro USB cable to USB J3 on nrf52840 DK for this test case?

RE: Test UART using GPIO

cbd — Wed, 22 Aug 2018 07:13:54 GMT

Hi,

Just to check:

Did you connect the ground wire from your USB-RS232 lead to a ground on the board?
Did you connect TX to RX on the lead to the board and vice versa?
Did you configure both ports for the same settings e.g. board rate, stop bits, parity, flow control etc?
Finally does the USB-RS232 lead give a 3.3V or a 5V output, you'll need 3.3V.