RF52840 Two instances of UART/UARTE

[Dermot Murphy]

Hi,

I have just started using the Nordic SDK (nRF5_SDK_15.2.0_9412b96) and am developing a low power application for a custom PCB using the rf52840.

I am developing using Segger on the PCA10056 development board initially.

Similar support queries seem to reference older versions of the SDK and/or replace files in the SDK itself.

The starting point was example: examples\ble_peripheral\ble_app_uart.

I would like to add a second instance of a serial interface (UART/UARTE).

The first instance will remain attached to the BLE.

The second instance will be connected to a device on the PCB.

Do any SDK files need to be modified to allow two instances to run in a low power application or have the issues (UART drawing two much current) been corrected in SDK 15?

Is the BLE example code using UART or UARTE and how is this determined by looking at the example code?

Will I need to include any other SDK files in the project because of switching to 2 instances, or are the files included by the example sufficient?

What changes do I need to make to the sdk_defn.h?

I do not need to use DMA.  Is it preferable to use UART or UARTE and what is the advantage of one over the other (aside from DMA)?  Is this in the documentation?

Does the BLE example code need to be modified when a second UART/UARTE is used by the application, or is it sufficient to only add new code for the second UARTE for the application?

Should the second UARTE use the same interface (APP_UART_FIFO_INIT) as the BLE example to initialise the UARTE?

Which include files are needed by the new application module?  Currently I have:

#include "nordic_common.h"
#include "nrf.h"
#include "bsp.h"
#include "app_error.h"
#include "app_timer.h"
#include "app_uart.h"
#include "nrf_uarte.h"
#include "nrf_drv_timer.h"

The application module is also using a timer, hence the inclusion of the timer include files.

Many thanks for any help you can offer.

Thanks

Dermot

[awneil]

Dermot Murphy said:

The first instance will remain attached to the BLE

Not sure what you mean by that ?

[Dermot Murphy]

Hi,

Thanks for your reply.

What I mean is that the BLE example code already uses one UART to provide serial comms over BLE.  I wish this to remain unchanged - that is the first instance of the UART initialised in the example, will remain unchanged in that it is still attached to the BLE code in the example.

I basically want the BLE example unchanged, and just add a second instance of serial comms (UART/UARTE) which I want to use with a sensor on my PCB.

Thanks

Dermot

[awneil]

So what will be connected to the first UART on your PCB ?

EDIT

A diagram might help ...

[Dermot Murphy]

Hi,

I wish to add a second UART/UARTE to communicate with a device on my PCB.

To answer your question, the first UART is connected to the BLE (refer to the example quoted), and I wish this to remain unchanged.

Thanks

Dermot

[awneil]

Dermot Murphy said:

the first UART is connected to the BLE

This is the bit that doesn't make sense:

The BLE is entirely internal to the SoC - so what is the first UART actually connecting to outside the SoC ?

In the examples, it is simply used for demo purposes to connect to a terminal on the developer's PC.

It seems that it may be unnecessary in your application.

Again, a diagram may help.

[Dermot Murphy]

Sorry I have no idea what the first UART is connected to in the BLE UART example.

I would refer you to the Nordic example quoted in the question.

To me, it appears to be used for transmitting debug data as a call is made in the example code to app_uart_put from the nus_data_handler handler which is handling the data received over BLE.  As a guess, I would say it is going out via the USB connection to the Segger Terminal.

Either way, I am not interested in the BLE usage of the UART it has initialised.

I only am interested in adding a second UART/UARTE to support the sensor on my PCB.

Thanks

Dermot

[Simon]

Currently, due to summer vacation, we are low on staff, and you may experience delayed answers.

I will just copy in some answers I found in some other tickets initially. Tomorrow/friday I will take a deeper look into your questions and try to give a more comprehensive answer

"app_uart does not support two UARTs. UARTE1 should be accessed through the driver while UARTE0 may be accessed through app_uart or the driver."

"I think it's easier to use the UART driver directly instead of using the Serial library for the second UART instance. Anyway, please try to build and debug the "Debug" target, it will give you a more verbose error message." (this was from a case where a customer was trying to do the same as you).

Take a look at the UART driver in the documentation: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsdk_nrf5_v17.0.0%2Fhardware_driver_uart.html&cp=7_1_2_0_19

Best regards,

Simon

[Vidar Berg]

As Simon said, you can use the already included UART driver to configure the second UART instance. Just remember to enable 'UART1_ENABLED' in sdk_config.h first.