EK-TM4C123GXL: Systick vs timers

John Hite

Part Number: EK-TM4C123GXL

My system clock is 80 MHz and I need an interrupt every microsecond. What are the pros and cons of using a timer vs systick? My assumption is that that the ARM based systick was made available for RTOS or scheduler purposes. I see no reason the ISR shouldn't update a variable too.

Thanks,

John

over 3 years ago

+1 Andy Peters over 3 years ago

Genius 3945 points

SYSTICK is always available, and if you need the timers for other more interesting use, then using SYSTICK to generate the one-microsecond interrupt is perfectly reasonable.

0 John Hite over 3 years ago in reply to Andy Peters

Intellectual 370 points

Thanks for the affirmation but I am afraid not all of my other uses are more interesting. :)

John

0 Andy Peters over 3 years ago in reply to John Hite

Genius 3945 points

The only reason, really, to not use SYSTICK is if you're using an RTOS that needs it, and you don't want to hook into it.

0 John Hite over 3 years ago in reply to Andy Peters

Intellectual 370 points

The RTOS needs it but it also wants 1 MHz ticks. So I let the ISR increment the time ticks whilst tickling the scheduler. I wrote up another version using timer 0 and made sure it works should we ever want the scheduler to see something other than 1 MHz.

Thanks again,

John

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EK-TM4C123GXL: Systick vs timers