On 12/22/2016 10:45 AM, Justin Pearson wrote:
> I have the same question.
> 
> I'm using the PRU's 200 MHz cycle counter to timestamp sensor measurements. 
> At 
> 200 MHz, this 32-bit counter overflows in 20 seconds. I would like to notify 
> a C 
> program running on the 1GHz host ARM processor as soon as it overflows.
> 
> *Is it possible to configure the PRU cycle counter to trigger an interrupt in 
> the host ARM when it overflows?*

Do you mean the Cycle register (offset 0x0C in the PRU_ICSS_PRU_CTRL
register bank)?  If so, this counter doesn't even wrap around (it
automatically stops when it hits 0xFFFFFFFF) much less generate an
interrupt.

> I know how to write PRU code to make the PRU trigger an interrupt in the 
> host, 
> but that's not quite what I want, since my PRU will be busy doing other 
> things. 
> I would like the cycle counter to trigger an interrupt automatically, without 
> the PRU having to check if it has overflowed.

Try using the IEP timer.  It will wrap automatically, and you can even
setup a configurable period by using compare register zero and setting
the CMP0_RST_CNT_EN bit.  You can also route an IEP timer event
(pr1_iep_tim_cap_cmp_pend) to the ARM core to generate an interrupt.

-- 
Charles Steinkuehler
[email protected]

-- 
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