RE: Programming external nrf51 module using nrf51 DK and mBed (if possible)

Einar Thorsrud — Tue, 21 Aug 2018 12:33:13 GMT

Hi,

1. Yes, the nrF51 DK has a debug out port that can be used to program the nRF51 on the module

2. The 32 kHz crystal is optional (never required). However you need to make sure that your applications is configured to use the 32 kHz RC oscillator instead. The SDK examples assume that a 32 kHz crystal is present, and will attempt to start it when initializing the SoftDevice, causing the initialization to hang while waiting for the oscillator to start (which it never does).

3. If a 32 MHz crystal is used, then the clock is simply divided by two. The CPU clock of the nRF51 is always 16 MHz.

4. Yes, that is correct. You use the Debug out port (either in the far left corner, or the same pins in the row to the right of the current measurement port on the DK. Note that you must ground the GND Detect pin to tell the debugger to use the debug out port instead of programming the local nRF51 chip.

5. The LDO is used by default. You can enable the optional DC/DC, which can is beneficial when powering with such a high voltage in order to avoid waisting power with the LDO. If the module don't have the optional DC/DC components or you don't care about current consumption, you can leave it as is, using the LDO. The default firmware uses LDO instead of DC/DC.