Taiyo Yuden EYSHJNZXZ (nRF52832) not working when using softdevice

[NewAce]

I am able to run nRF5_SDK_12.2.0/examples/peripheral/blinky using the armgcc toolchain without any issues but any example with a soft device enabled (e.g. nRF5_SDK_12.2.0/examples/ble_peripheral/ble_app_beacon) does not show up using LightBlue or nRF Toolbox. If I modify the sample code to turn on an LED as the first instruction in the program, it never gets there.

I have the same problem running the mbed5 blinky example (using mbed-cli instead of nordic SDK/armgcc). This works fine on a nRF52-DK but not on the EYSHJNZXZ. I am aware that mbed5 includes the s132 2.0.0 soft device, which tells me that the moment a program image includes the softdevice it won't run on the EYSHJNZXZ module.

What am I missing? Are there any special considerations for using the Taiyo Yuden module compared to a stock nRF52832? I'm at a loss. Any assistance would be greatly appreciated.

[NewAce]

Hello Kristin,

Thanks for the feedback. For the benefit of others, when using MBED (OS5), I determined that the define MBED_CONF_NORDIC_LF_CLOCK_SRC needed to be changed to NRF_LF_SRC_SYNTH so that it derives a 32KHz clock from the 32MHz crystal. This seems to work for all MBED examples, including "blinky" and "ble-LED".

targets.json: (MCU_NRF52 section)

"config": {
            "lf_clock_src": {
                "value": "NRF_LF_SRC_SYNTH",
                "macro_name": "MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC"
            },

...

[FormerMember]

Another option is to use the internal RC oscillator instead of the synthesized clock. The synthesized clock requires the 32 MHz crystal to run all the time, while the RC oscillator doesn't. The RC oscillator will therefore use less current.