Low Power Comparator

[mauro]

Hello,

I'm working with nrf51822 on a custom board and i'd like to use the LPCOMP as wakeup source. I configured the module by the code listed above:

void lpcomp_init(void) { NRF_LPCOMP->PSEL = 0x00000000; NRF_LPCOMP->REFSEL = 0x00000006; NRF_LPCOMP->ANADETECT = 0x00000000;

NRF_LPCOMP->ENABLE = 1;
NRF_LPCOMP->TASKS_START = 1;

while (NRF_LPCOMP->EVENTS_READY == 0) {

}

}

I don't know if the configuration is correct but the function stuck into the while cycle. Am i doing something wrong? Could be an hardware issue related to the silicon revision of my chip?

Thanks in advance and best regards

[John Kelley]

I think you're misunderstanding the use of the EVENTS_READY register. This will be non-zero when an event has occurred, i.e. your trigger conditions have been met.

[mauro]

Maybe you are right, but the nRF51 Reference Manual says this:

"The LPCOMP is started by triggering the START task. After a start-up time of tLPCOMPSTARTUP the LPCOMP will generate a READY event to indicate that the comparator is ready to use and the output of the LPCOMP is correct"

so i don't know. Thanks for the response John!

[Ole Morten]

Your code snippet looks reasonable. The LPCOMP is only available on second revision chips, so if you try to use this on a first revision chip, I assume you'll see something similar to what you see, since the register isn't actually there.

You can take a look at the PCN for an overview over the changes, and you may also have use in reading the migration whitepaper.

[mauro]

thank you for the response!