Thanks Graham. Follow-up questions: 1. Where exactly did you find this information? I looked through the TRM and SRM but couldn't find anything definitive.
2. Is the 200-MHz PRU driven from the same 24 MHz oscillator that drives the CPU? If so, is it correct that the PRU cycle counter increments precisely once for every 5 CPU cycles? Thanks for your help. -Justin On Tuesday, April 25, 2017 at 7:35:19 PM UTC-7, Graham wrote: > > The CPU in a BBB runs from a 24 MHz Oscillator. > There is a 25 MHz oscillator on the board, but that is for the Ethernet. > --- Graham > > == > > On Tuesday, April 25, 2017 at 7:09:50 PM UTC-5, Justin Pearson wrote: >> >> How can I find out whether the PRU and CPU are driven by the same >> oscillator? Specifically, a colleague told me that the IEP timer (which I'm >> reading with the PRU) is driven by a 24 MHz oscillator that's PLL'd so the >> timer increments at 200 MHz, whereas the CPU is driven by a 25 MHz >> oscillator PLL'd so that the CPU runs at 1 GHz. >> >> It seems to me that if they're driven by different oscillators, then they >> could drift apart over time. >> >> Page 1177 of the TRM (spruh73n.pdf) mentions a 32-kHz crystal oscillator, >> but I don't see how that's related. >> >> Also, are these oscillators within the Sitara SoC, or somewhere else on >> the BBB? The SRM just references 24.576 MHz oscillator (pg 70 of e14 >> BBB_SRM_rev 0.9.pdf), and I'm not sure how that's related to the 24/25 MHz >> oscillators my colleague mentioned. >> >> Thanks for your help. >> >> -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/a001d53b-ce5d-4b05-a0a1-d703971cb75e%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
