Sensor Readings using UART

[graceling]

I am trying to use a sensor that needs 9600 baud rate with the nRF52840-DK. I've set the baud rate to 9600 on the sdk_config.h. Would I still be able to see the transmit/receive data on putty if the baud rate is set to 9600 for the sensor and the DK runs on 115200? At the moment, I can only see things on putty if the baud rate is set to 115200 and it's just basically the DK talking to itself.

I'm having trouble with getting any responses from the sensor, both from the custom PCB and just connecting the sensor to the assigned GPIO pins on the DK. I am able to send commands to the sensor ie "Z\r\n" (I think) but I am not getting the right response back from the sensor. In this case, the temperature reading. 

I'm using the SDK 15.2 and started off with the UART example (UART library).

What am I doing wrong here?

[Ashish]

Hi,

To confirm, you want to communicate with your sensor via UART and and also use it for sending data over to the putty?

If this is the case then you will need 2 UART instances, one to communicate with the sensor and other for the Interface MCU on DK.

The UART example uses the default pins connected to the Interface MCU, so you are able to communicate with putty.

You can try the UART driver and create another UART instance and use that to communicate with your sensor.

[graceling]

Do I use the same pins when creating the other instance or connect the sensor to different GPIOs? Or does it not matter?

[Ashish]

Check the documentation for the DK board.

P0.05 - P0.08 are connected to the interface MCU, and these are the ones being used in the example code. Choose some other GPIO for communicating with the sensor.

[graceling]

Sorry, I'm really a bit clueless over this. I've created the two instances, assigning different sets of GPIOs and different baud rate (115200 for DK instance and 9600 for sensor instance).

I can see data transmitted/received on putty coming from the DK but how do I get the data received from the sensor? I'm using app_uart_get() and app_uart_put() to send and receive data and it seems like I can only communicate with the DK. There's no way to specify which instance I want to receive/transmit data from. Am I meant to use a different function? Or are the same data/commands being sent to the different UART instances?

I just want to get the readings from the sensor but I don't know how to access that.

[Jørgen Holmefjord]

You should not use app_uart with two instances, it does not support multi-instance. The newer library, nrf_serial, is a better choice. There is a Serial Port Library Example with two UARTEs in the SDK.

[graceling]

Hi thanks for this. I've now moved onto the ble_app_uart example and got that working. But is it possible to use custom pins for the Rx and Tx to get that example to work? Is it possible to use UART with Soft Device? I've got a custom board that I eventually want to use that will be using the bluetooth service.

using a custom board and trying to get UART to work on that. How can I use UART with the Soft Device? 

[Ashish]

Hey,

ble_uart example uses app_uart. Check the uart_init function, you can change the pins in that function.

graceling said:

But is it possible to use custom pins for the Rx and Tx to get that example to work?

Yes, it's possible.

graceling said:

Is it possible to use UART with Soft Device?

Yes

graceling said:

How can I use UART with the Soft Device? 

ble_uart example does exactly that.