MetaWear custom firmware

Question

Hello, I am trying to upload my custom firmware to the MetaWear RG (nrf51822) platform but currently without luck. Steps that I have performed: 
 
 Connected to the device using the debug out of the nRF51DK as described here 
 Uploaded Softdevice S130 
 Uploaded custom application 
 
 Now, uploading seems to be working fine, but the application/mcu doesn't seem to start/work. I believe the problem lies in not correctly configuring the application to use the 32MHz external crystal, which the MetaWear uses. 
 To try to achieve that: 
 
 Step 1 
 it is being suggested to write the value 0xFFFFFF00 to the UICR (User Information Configuration Register) at address 0x10001008 (XTALFREQ). 
 # After softdevice upload and when the UICR can be written to
# Using nrfprog.exe (not tested, but should work)
nrfjprog.exe --snr <your_jlink_debugger_serial_number> --memwr 0x10001008 --val 0xFFFFFF00
# Using jlink (my method)
w4 0x10001008 0xFFFFFF00
 
 I can verify that address 0x10001008 has been written to correctly. 
 Step 2 
 I edited the nrf_drv_config.h to use NRF_CLOCK_XTALFREQ_32MHz . 
 Step 3 (Edit 1) 
 based on this I changed the definition at the top of the system.nrf51.c file to 
 #define __SYSTEM_CLOCK (32000000UL)
 
 and I also explicitly enabled the use of the external 32MHz crystal in the application code like: 
 int main(void)
{
 // Set the external high frequency clock source to 32 MHz
 NRF_CLOCK->XTALFREQ = 0xFFFFFF00;

 // Start the external high frequency crystal
 NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
 NRF_CLOCK->TASKS_HFCLKSTART = 1;

 // Wait for the external oscillator to start up
 while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) {}

 while (true) {
 // run application
 }
}
 
 
 Using nRF51_SDK_9.0.0_2e23562 
 Any clues? Has anyone successfully managed to run custom code in the metawear? 
 Any help appreciated! Thanks!

Tanasis! · Accepted Answer

For people that haven't figured this out yet, in order to port your work to any custom hardware you need to know 
 
 Flash/RAM size of the nRF chip and the SoftDevice version. Based on that, the correct information needs to be passed in the linker 
 the use of internal/external clock and the clock-frequency. This information is used to adapt:
 
 
 the system.nrf51.c file 
 
 
 in case of external clock also explicitly enable it the beginning of the program in main: 
 int main(void)
 {
 // Set the external high frequency clock source to 32 MHz
 NRF_CLOCK->XTALFREQ = 0xFFFFFF00;

 // Start the external high frequency crystal
 NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
 NRF_CLOCK->TASKS_HFCLKSTART = 1;

 // Wait for the external oscillator to start up
 while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) {}

 while (true) {
 // run application
 }
 }
 
 
 
 
 
 For more details on this read the following: turlucode.com/.../