nrf52dk + mbed + external board (Holyiot 17095)

[taras]

Intro:
  Goal: have small (one size <10 mm) board with BLE.
  Decide this:
  - use Holyiot 17095 as a board.
  - use mbed OS / v5 (Online IDE) as a development env.

  Tried to flash external board (Holyiot 17095) with:
   - with J-link (made from STLink V2 by reflashing).
   - with nrf51-DK
   - with nrf52-DK. (by drag & drop and nrfGo)
  Connection Used P20 by this schema.
  All cases showed that flashing was well, but the blink example did not work. On DK-52 & DK-51 blink worked well.

Tried to flash BLE firmware that worked well on DK, on custom board - I saw the device on nrfConnect App (Android) but can't connect - error: "Error(0x85):GATT ERROR".

Question:
  - How to flash external board and make it run? 

Guess:
  - I need to flash some bootloader to my external board.

Any ideas or recommendations are welcome! Thanks.

[Marcio Montenegro]

I think this module does not have low frequency xtal

[Kenneth]

Hi,

In general you may find this interesting:
https://devzone.nordicsemi.com/f/nordic-q-a/31222/nrf5-sdk-mbed 

Maybe you have some UART logging that is crashing if not connected? Have you tried debugging to check if there is an assert or what may be preventing the application from running as expected?

Best regards,
Kenneth

[KovTam]

I found same issue with this holyiot 17095 module. Did you find solution finally? 

[Nguyen Hoan Hoang]

Try this module instead. Smaller and complete with all DC inductors & all crystals builtin with full 30 I/O, certified

https://www.i-syst.com/products/blyst-nano

https://www.crowdsupply.com/i-syst/blueio832-mini