EMAC LL Descriptors

cbrieske
Posts: 3
Joined: Tue Sep 24, 2019 7:47 am

EMAC LL Descriptors

Postby cbrieske » Tue Sep 24, 2019 7:53 am

I have a few questions related to PTP (IEEE1588) support on the EMAC.

According to the technical reference manual, TDES6 & TDES7 are updated with the timestamp captured for the corresponding transmit frame. What is not clear, is where this timestamp is sourced from.

Is anyone able to shed any light on what timer might be used for this timestamp?

chuledeco
Posts: 6
Joined: Thu Feb 13, 2020 3:22 pm

Re: EMAC LL Descriptors

Postby chuledeco » Mon Jun 29, 2020 10:19 pm

Hello, could you finally found the way to implement PTP on ESP32?

cbrieske
Posts: 3
Joined: Tue Sep 24, 2019 7:47 am

Re: EMAC LL Descriptors

Postby cbrieske » Tue Aug 04, 2020 7:26 am

Unfortunately no. There is an unfortunate lack of information around how to actually enable the timestamping features. Unless i'm missing something obvious, I cant seem to get any timestamps for either TX or RX frames. But I also dont know where the timestamp values are actually derived from. Both of these are key point for actually getting this to work, and I have been unable to get any response from espressif on this subject so far.

I am more than happy to work on porting PTPd, but we really need some input from someone at espressif here!

Its really frustrating, and writes off a whole host of application because they simply haven't fully documented the EMAC.
I'ts annoying that I'm having to look at other MCU's simply because of a lack of documentation.

ESP_Sprite
Posts: 3729
Joined: Thu Nov 26, 2015 4:08 am

Re: EMAC LL Descriptors

Postby ESP_Sprite » Tue Aug 04, 2020 11:21 am

Let me ask the digital team; will get back to you.

Edit: I asked: the PTP uses the internal 80MHz APB clock as a clock source for a 64-bit counter. Can't tell why you can't get anything working out of it, though.

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