Timer with prescaling

[Jean-marie]

I use sdk 15.3.0 / nrf52832 / SD_132.

How to use the prescaler of a timer for an event every 24 hours ?

An example will be very explicit.

Best regards,  Jiemde

[Karl Ylvisaker]

Hi,

Have you seen the Timer documentation regarding prescaler options?

As you see from the prescaler register, you may at most set the timer prescaler to 2^9, which gives you 16M / 512 = 31250 ticks per second.
So, then we need to establish the size of our TIMER. We see that the different BITMODES available ranges from 8 to 32 bit.
Setting it to 32 bit gives us 4294967296 ticks til overflow, which with the 512 prescaler gives us ~36 hours till overflow.
Thus, you may set the timer to compare for the value 2700000000 - which is ticks per second times seconds in 24h.

You will now receive a COMPARE event every 24h. When this happens, you should remember to also CLEAR your timer - to avoid counting all the way to 36h before restarting at 0.

Is this what you were looking for?

Best regards,
Karl