PRU IEP timers non-responsive


I’m trying to write a simple program to test the IEP timers. Ideally I’d like to be able to poll the timer and get an unsigned long value back, but for this test, I followed what I read in this post:

With a few minor changes – I provide a different GPIO pin, made it loop forever, and made the frequency for the square wave ~2kHz.

I also have a different way of configuring the IEP/INTC. I manually defined the addresses:

#define IEP_HOME ((volatile unsigned long*)0x2E000)
#define TMR_GLOBAL_CFG ((IEP_HOME+0x00))
#define TMR_COMPEN ((IEP_HOME+0x08))
#define TMR_COUNT (
#define TMR_CMP0 ((IEP_HOME+0x48))
#define TMR_CMP_STATUS (
#define TMR_CMP_CFG (*(IEP_HOME+0x40))

#define INTC_HOME ((volatile unsigned long*)(0x20000))

#define INTC_SECR0 ((INTC_HOME+0x280))
#define INTC_SECR1 (

And I configured them like so:

TMR_GLOBAL_CFG &= 0xfffffffe; // disable timer

TMR_COUNT = 0x0; // reset timer

TMR_CMP_STATUS = 0xff; // clear compare status

TMR_CMP0 = 100000; // 0.0025 SEC @ 200 MHz

TMR_COMPEN &= 0xff000000; // set compensation to 0

TMR_CMP_CFG &= 0x03; // enable cmp0 and reset on event

INTC_SECR0 = 0xffffffff;
INTC_SECR1 = 0xffffffff;

TMR_GLOBAL_CFG = 0x11; // enable counter

When I read from TMR_COUNT, it’s always 0, and the interrupt never fires. What am I missing?


1 Like

Ok I figured it out lol.

I was adding the actual byte-size offsets to pointers to longs, so it was being offset by 4x as much as I would have expected.

The program works fine otherwise.