Timing bootloader

[nrbrook]

My firmware goes into system off state when idle and wakes on GPIO (button input). I want to display an indication to the user for a fixed duration, so I will modify the bootloader to set the GPIO output, but I need to know how long the bootloader took to boot as I then need to subtract this from the duration the firmware waits before ending the indication.

So is there a way to measure the bootloader boot duration and pass this to the application? Or is there a timer which starts on boot that I can read?

[bjorn-spockeli]

Hi Nick,

you can start a TIMER or RTC upon entering the bootloader. Since the bootloader branches to the applicatio, the TIMER or RTC will keep running and you can stop and read out the counter value in the application,

Best regards

Bjørn 

[nrbrook]

Thanks. In the bootloader I have this:

NRF_RTC2->TASKS_STOP = 1;
NRF_RTC2->TASKS_CLEAR = 1;
NRF_RTC2->PRESCALER = 0;
NRF_RTC2->TASKS_START = 1;

In the firmware I have this:

uint32_t count = NRF_RTC2->COUNTER;
uint32_t ms = count * 1000 / 32768;
NRF_RTC2->TASKS_STOP = 1;
NRF_RTC2->TASKS_CLEAR = 1;

However, ms is 0. Am I missing something?

[bjorn-spockeli]

You need to start the LFCLK so that the RTC has a clock source, i.e. 

NRF_CLOCK->TASKS_HFCLKSTART = 1

while(!EVENTS_LFCLKSTARTED) {

// wait for LFCLK to start before starting RTC

}