Unable to Get BLE Advertising or GPIO Blink on Custom ISC-nRF52832-A PCB

[Chinmay Mulgund]

I’m developing on a custom PCB that carries the ISC-nRF52832-A (nRF52832) and a BMA400 sensor. I can successfully flash the chip over SWD using an ST-Link v2 (connected to VCC, SWDIO, SWCLK, GND) but I cannot get any basic functionality to work—neither BLE advertising nor even a simple LED blink on a GPIO. Below are the details of what I’ve tried and the observed behavior:

Board & Toolchain

• Custom PCB with ISC-nRF52832-A

• SWD header pins: VCC (3.3 V), SWDIO, SWCLK, GND
• ST-Link v2 as uploader/debugger (configured to 3.3 V target)

            Platform: Windows 10, Arduino IDE & PlatformIO (NordicnRF52 platform 10.9.0, Arduino core for Adafruit nRF52)



Verify Log:

Sketch uses 2100 bytes (0%) of program storage space. Maximum is 409600 bytes.
Open On-Chip Debugger 0.10.0-dev-00254-g696fc0a (2016-04-10)
debug_level: 0
0x4000
adapter speed: 10000 kHz
target halted due to debug-request
** Programming Started **
wrote 4096 bytes from file …/nrfBluetooth.ino.hex in 0.156s (25.6 KiB/s)
** Programming Finished **
** Verify Started **
verified 2220 bytes in 0.047s (46.2 KiB/s)
** Verified OK **
** Resetting Target **
shutdown command invoked

Flash and verify always succeed, but no visible behavior on the board.

Looking forward to your guidance.

[Asbjørn]

Hello Chinmay,

With custom boards behaving this way there's a couple of things I'd start by checking.

Q1: Do you have an external 32k crystal on your board? If not, have you defined to not use LFXO, but LFRC instead?

Q2: Do you have the components for the DCDC  on you board? If not, have you made sure you're not configuring to use it?

Q3: Are you able to run code in debug mode or with RTT enabled, is the program counter moving and are you seeing any print on the uart/RTT?

Best regards

Asbjørn

[Chinmay Mulgund]

Hello Asbjørn,

Board & wiring

• ISC-nRF52832-A module (pins 1–4 exposed):

  • Pin 1 → VCC (3.3 V)

  • Pin 2 → SWDIO

  • Pin 3 → SWCLK

  • Pin 4 → GND

• BMA400 sensor on I²C (SDA → P0.20, SCL → P0.19)

• Programmer: ST-Link v2, 3.3 V target, wired only to those four SWD pins

I’m building & flashing from the Arduino IDE using the SandeepMistry nRF5 (BLEPeripheral) library.

Q1) 32 kHz crystal?

• No, I did not populate an external 32 kHz crystal or load capacitors on my PCB.

• In my Arduino sketch I haven’t overridden the clock source, so by default the SoftDevice is trying to use LFXO.

Q2) DCDC converter?

• The ISC-nRF52832-A module does not include the external DCDC components.

• I have not enabled DCDC in software, so it should be using the internal LDO regulator.

Q3) Debug / RTT

• Attaching ST-Link in debug mode halts the CPU at the reset vector (0x00001DA0) and it never advances into setup() or loop().

• I don’t have a UART or RTT on my board, so I cannot see any console output.

I was under the impression that the ISC-nRF52832-A has an in-built 32 kHz crystal—could you please guide me on whether this is a hardware issue (missing crystal) or a software/configuration issue?

Thanks again for your help!

[Asbjørn]

Hello,

ISC-nRF52832-A isn't a product we sell, it's a product that contains one of our nRF52832. It does not seem to have LFXO available, so in your case, I'd recommend using the LFRC as LFCLKSRC. There's a LFRC built into the nRF52832 but this has to be enabled for it to be used. It's a config for the FW setup.

The DCDC seems to be available, but not entirely sure if that's valid for all module variant. If you're sure it's not enabled then this wouldn't be a problem.

I'd recommend you to compare this with the modules datasheet to confirm. Is this the module you have: https://evelta.com/content/datasheets/495-ISC-nRF52832-A.pdf

Best regards

Asbjørn