How to convert 16-bit Timer to 32-bit?

Nmo.1 · ‎2022-01-21

Hello everyone,

I'm using 4 timers of a stm32 nucleo board to count the increments in encoder mode. 2 timers are 16 bit and 2 others are 32 bit.

The increments can be between -1,000,000,000 and +1,000,000,000.

With 32 bit timers, there is no problem because they can be -2147483648 to +2147483647.

But 16-bit timers can be -32768 to +32767 so several times an overflow occurs.

It is impossible to find where the overflows occur to simply add each time -32768 or +32767 and solve the problem. So I need to somehow convert the 16-bit timer to 32 bit.

is it possible? Do you have any idea?

Thank you so much for your help.

waclawek.jan · ‎2022-01-21

In software, sample the encoder timer's value regularly - more often than half of period at maximum input frequency - and calculate the number of overflows from that.

There's no bulletproof way to do it in hardware.

You may want to consider using a cheap small STM32 as a slave to add more 32-bit timers.

JW

SofLit · ‎2022-01-21

Dear @Nmo.1 ,

I think this AN2592 "Achieving 32-bit timer resolution with software expansion for STM32Cube and Standard Peripheral Library" can help you.

SofLit

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