Re: nRF52832 hardware cycle count freezing at chip start
Chettimada, Vinayak Kariappa
I assume, you mean, you are using nRF52832 chip and your custom board; and using a Zephyr build using the BOARD=nrf52_pca10040.
Do you have the 32KHz crystal mounted in your custom PCB? If not, you will need to use the internal RC oscillator by enabling CONFIG_CLOCK_CONTROL_NRF5_K32SRC_RC=y.
Currently there is no watchdog driver for nRF52 contributed yet to Zephyr. I am not an expert on this peripheral, but I do notice in your code, you enable interrupt from the watchdog peripheral, hope you have setup interrupt handler correctly, clear the events and kick the dog sufficiently, etc.
If your application needs watchdog, I would advise you implement a watchdog driver following the Zephyr driver model (include/watchdog.h and in drivers/watchdog folder). We will be glad to review your driver and a simple sample application.
Please remember that nRF52 is a ultra low power chip and there is no functional ARM systick timer, the system timer is implemented using the NRF_RTC peripheral.
The resolution of each tick is in 32KHz units. If you print in busywait, you will see lot of lines with same values until each 32KHz (*if* UART tx time is very much less than 30.517 us, which I doubt).
Ok, you want to wait 100 microseconds and your printk inside the “for” loop in k_busy_wait consumes more time (I am certain) and the loop does not break out correctly.
Could you please explain the symptoms of the problem without any of your debugging (printk influences the k_busy_wait) ?