Not able to send data over UART on nRF52810

[Sudeep R J]

Hello,

I am not able to send a command from the BLE (52810) to a DSP over UART which are on my custom board. I have modified a program that uses UART for logging purpose. I have also modified a UART loopback program to talk to my DSP and in that program the UART connection is working properly and I am able to send a command to DSP and receive a response from DSP on the BLE. But in the program in which UART was used for Log, I am not able to send anything from BLE to DSP i.e there is no data that the DSP is receiving. I have disabled the NRFX_UARTE_CONFIG_LOG_ENABLED by defining it as 0.

What is the problem here? Is the UART not getting routed to the DSP?

Kindly help me with this issue.

Thanks & Regards

Sudeep R J

[Hung Bui]

Hi Sudeep, 

Have you tried to disable log completely ? (set NRF_LOG_ENABLED = 0)

Or you can set NRF_LOG_ENABLED = 1 but use RTT logging instead of UART.

You can refer to our ble_app_uart example where we use RTT log and UART interface at the same time.

[Sudeep R J]

Hello Hung Bui,

Yes I did disable the log completely. 

I do not want the log messages anyway so i have not enabled the RTT log also. I compared my sdk.config file with that of ble_app_uart but still there is no data that can be seen on the DSP Rx.

Thanks & Regards

Sudeep R J

[ovrebekk]

Hi 

Sorry for the slow response. Hung is currently out of office, and I will help out in the mean time. 

Did you have any progress with this?

Do you get any error messages in the code when you try to enable the UART, or write to it?

Have you tried to probe the UART pins with a scope or logic analyzer to see if there is any activity?

Best regards
Torbjørn

[Sudeep R J]

Hi Torbjorn,

I think there is a hardware issue with my board. I was pulling up the DSP reset pin from the BLE and it was not happening as the BLE and DSP work at different voltages. So the voltage given by the BLE is not sufficient for the DSP Reset pin to be pulled high.

I have figured out till this. So a quick rework to my board should work for me I guess.

Thanks for your response.

[ovrebekk]

Hi

If your devices are running at different voltages you would need some kind of level shifter on the signals to convert the voltages accordingly. 

For one directional signals, such as the reset pin, you can typically get away with a simple transistor circuit, but for bidirectional signals it is a bit more complicated (either a more complex transistor network or a dedicated level shifter chip is needed). 

Best regards
Torbjørn