RE: nRF52840 DK VS Adafruit nRF52840 Feather

Chris Little — Wed, 04 May 2022 21:49:55 GMT

I am assuming that whatever log routines you are using in your app are directed to the uart console based on the statement that you can see them in the serial port terminal when using the nRF52840DK

The nrf52840DK provides both the JLINK interface as well as a virtual USB to serial adapter to the target mcu uart when using the USB port on the short side of the DK board. It looks like the feather brings the target mcu uart out to the through holes labeled RX and TX on the edge of the board.

Use a separate USB to TTL level UART adapter between your PC and those pins and you should see the output on the uart provided by the adapter. If not you may need to make sure flow control is not enabled in your application as the feather does not utilize uart HW flow control while the DK does have those signal routed to the virtual adapter.

RE: nRF52840 DK VS Adafruit nRF52840 Feather

austin944 — Wed, 04 May 2022 19:39:23 GMT

Do you have source code somewhere, or an example of how you are calling your log function? Are you using the Nordic NRF_LOG_ functions, for example?

I don't know how the Feather board works, but Adafruit mentions USB CDC on their web site, so I wonder if they are using that to print logging information. With the nRF52 SDK I think you have to explicitly include the USB CDC firmware to use it.

I am aware of two different ways to print logging information on the nRF52840-DK:

1. With the SEGGER debugger, you can enable logging (NRF_LOG_* calls) with the RTT backend. You bring up the RTT window with the Nordic software and observe the logging there.

2. You can attach an external serial port and include the NRF52 uart firmware. Connect the pins of the external serial port to your DK (typically USB-to-serial).

I have used both methods on my project using the Nordic Dongle (nRF52840) with a SEGGER debugger.

The Nordic development environment gives you great flexibility, lots of features, and potentially higher performance than what Adafruit gives you, at the cost of greater complexity. You need to decide if the greater flexibility/features/performance is something you really need for your project.