How to get a E73-2G4M08S1C nRF52840 to work

1

I have some E73-2G4M08S1C modules, basically a nRF52840 chip with the basic components around it, including a crystal and antenna. They are small and very low power SMD BLE devices.

I cant get the devices to work!
I experimented with some other nRF52840 devices, and they work right away (via Arduino or PlatformIO). So I started searching.

It appears, the E73 does not have anything preloaded on it (whilst many other boards have). So I figured out to add a SoftDevice (v 140) and a Bootloader using the Programmer of the nRF tookit and a Jlink (Segger). That all works fine. After that, I can indeed upload the application! That app sends a simple BLE beacon (that app works on other nRF52840 board). But on the E73 nothing happens. It is like it is not actually starting the app. I also tried an app with an alternating pin, but also do not see that or any pin alternating.

I also tried the SDK from Nordic, it runs under VisualStudioCode. I am able to flash an example app on the chip and also then nothing happens.

Does anyone know what else to do to prepare a clear nRF52840 chip for running an application, besides buring the SoftDevice/Bootloader and the app itself? Is there special Pins to have high or low, or ???

2

What carrier board do you place your E73 module on? The user manual

https://www.cdebyte.com/pdf-down.aspx?id=560

shows that two pins are for connecting a 32.768 kHz crystal, aka the low-frequency crystal oscillator (LFXO). The Arduino board definitions may require that such a crystal is connected to the nRF52840, and if not, fail at low-level clock initialization and just hang up.

E.g., when using the feather nrf52840 express board variant,

The chip has a fallback (internal RC oscillator, less accurate), that’s what LFRC is.

So, you could try to first of all post the full platformio.ini you’re using, so that we can figure out what that board definition assumes is there, hardware wise.

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3

@maxgerhardt You are a champion, thanks a lot!! Indeed was my board definition derived from adafruit_feather, and indeed assumes that definition a secondary crystal. So I changed the definition to ‘adafruit_feather_nrf52840_sense’ which does not assume this crystal, and immediately it works! This was my blind spot.

So, this platform.ini works, the one nrf52840_DJ based on the feather not.

[env:nrf52840test]
platform = nordicnrf52
board = adafruit_feather_nrf52840_sense
;nrf52840_DJ
;nRF52840_DJ dk
framework = arduino
monitor_speed = 115200
upload_protocol = jlink
;upload_protocol = mbed
;upload_port = COM23
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