IEP timer on PRUs on the Beaglebone AI and Beaglebone Black

[jo...@pocketnc.com]

I'm attempting to use the IEP timer on the PRUs on the Beaglebone AI (as wells the BBB), but am a bit confused about the difference between SR1.1 and SR2.0. The technical reference manual for the am572x has two separate sections for the IEP, one for SR1.1 and one for SR2.0. I implemented two different PRU programs that implement the basic programming sequence described in section 30.1.11.2.2.3 (for SR2.0) and section 30.2.11.2.2.3 (for SR1.1):

SR2.0 program: https://github.com/PocketNC/cloud9-examples/blob/iep_tests/BeagleBone/AI/pru/blinkExternalLEDWithIEPTimer.pru2_0.c

SR1.1 program: https://github.com/PocketNC/cloud9-examples/blob/iep_tests/BeagleBone/AI/pru/blinkExternalLEDWithIEPTimer.pru1_1.c

I haven't tested the SR1.1 program on the Beaglebone Black, but I've been debugging programs that seem to initialize the IEP using that method, so I believe it should work on the BBB. The SR1.1 program does not work on any of the prus on the Beaglebone AI. The SR2.0 program only seems to work on pr2_0 and pr2_1 on the Beaglebone AI. Why doesn't it work on pr1_0 and pr1_1?

I'd appreciate any information that could explain the difference between SR1.1 and SR2.0 and the IEP Timers on the PRU with respect to the BBB vs the BBAI. Thanks!

[John Allwine]



I must have inadvertently set the CMP0_RST_CNT_EN bit on the COMPARE_CFG register on pr2. After setting that in the setup function, it works on both PRUs.

Does anyone know why the SR1.1 section is in the reference manual? Can the PRUs be configured to use SR1.1 over SR2.0?

 



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