STM32F777 revision A RMII errata symptoms

[Thanh Phan]

Posted on April 29, 2017 at 06:38

Ethernet section of my custom board is the same as the STM32F746 discovery board. The same code (start ethernet and reply to ping) works reliably on the discovery board. But on my board (at all speed and duplex modes):

(1). Sometime after reset it works fine, I could ping continuously for several hours without any packet lost

(2). Sometime after reset it does not work or misses lot of ping. No ethernet interrupt fired. The MMCRFCECR has non-zero values.

(3). I am using macOS to ping, some time it responses

ping: sendto: Host is down

In this case, there is no output at the RMII RXD0, RXD1. 

Questions:

- Anyone knows in case (3) the computer will not send out any packet or computer does send but my board could not received?

- Are these symptoms caused solely by the RMII errata of revision A silicon? My main concern is PCB/schematic error, I want to fix as early as possible if there are.

- Is there anyway to recover from this error state by software? (reset the MAC?)

#ethernet #stm32f7

[Richard Peters]

Posted on May 01, 2017 at 08:57

I use the STM32F767 with ethernet (on the Nucleo-144 board), and I recognize almost everything you write. The only thing that surprises me is '

there is no output at the RMII RXD0, RXD1'. I haven't done any measurements, but I would expect that even in the presence of the ethernet bug that packets do get transferred over RXD0 and RXD1 to the MAC, and that at that point they are filtered out.

I have found a method that some could qualify as a workaround: When I see CRC error frames, I switch the RMII REF CLK pin configuration back to default (input pin, default speed, no alternate function), and then configure it again to its ethernet alternate function. This seems to have a 50% chance of fixing the problem. So after a few received frames, there's a good chance that ethernet frames can be reliably received.

Resetting the MAC, re-inserting the ethernet cable, or resetting anything other than the RMII REF CLK pin configuration does not seem to have any effect.

(By the way, does anyone know if/how/when I can get STM32F767 Nucleo's with the Z revision instead of the A revision?)

[Thanh Phan]

Posted on May 01, 2017 at 11:56

'

there is no output at the RMII RXD0, RXD1', I suspected this due to my computer stop sending out ping message after too many failures, at that time the LINK/ACT LED does not blink.

I could not understand why such critical, easy to reproduce bug got into production release. A major problem is when we order new chips, we have no idea if we will receive rev.Z or faulty rev.A. I tried to contact local ST representative to help on this issue, but no response yet.

This is disappointing!

[Lei Zong]

Posted on September 30, 2017 at 03:46

We are currently also running into the silicon revision issue for the STM32F777NI processor.  We needed to get revision Z, not revision A, due to the RMII issue in the errata.  When we ordered samples from Digikey, they were rev A.  We'll try Mouser next, but we don't have high hope for it.  We also have an Avnet rep that's working with us in parallel to get some ST's attention, but as usual, we are in a pinch for schedule.  Have you guys found a way to get the Rev Z silicon?  Any feedback is appreciated.

[Tesla DeLorean]

Posted on October 01, 2017 at 18:52

In the US you'd be better off talking directly with your local ST sales office, and get samples from your rep.

[Imen.D]

Posted on October 02, 2017 at 11:44

Hello

lzong

,

You should contact your local ST sales representative from the list indicated at this

http://www.st.com/content/st_com/en/contact-us.html

.

Kind Regards,

Imen.

[Lei Zong]

Posted on October 02, 2017 at 12:49

We have been working with our local Avnet representatives as well, but the only thing they can do is contact ST's technical contact and they are at the mercy of ST's support. Our designs are typically high complexity but not high volume so we are a small fish for ST. The support from ST we've received traditionally has been fairly poor. We've been trying to get some answer from our ST technical contact for several weeks now to no avail, that's why we decided to just order some samples from distributors to see what silicon versions we are able to get. Unfortunately the silicon version is the one with serious RMII error and won't work in our application.

Lei

Thumbed with care from my iPhone

[howard n2wx]

Posted on October 02, 2017 at 17:56

(3). I am using macOS to ping, some time it responses

ping: sendto: Host is down

That response suggests an attempt to ping a hostip lacking an arp map entry.    'arp -a -n' probably returns a record for the hostip in question as (incomplete) expired.

[Tesla DeLorean]

Posted on October 02, 2017 at 16:39

>>We have been working with our local Avnet representatives as well, but the only thing they can do is contact ST's technical contact and they are at the mercy of ST's support.

They should be able to order specific parts or source samples. They should also have some level of engineering support, or FAE in-house. One wonders what value-add they bring to party otherwise.

Would recommend talking and getting to know ST FAE at the assorted demo/seminar events held locally.

What would be useful from ST would be specific production dates and fully qualified part numbers for fixed silicon.

[Laurent VERA]

Posted on October 02, 2017 at 21:14

Dear Lei,

Actually, all our distributors should be aware of silicon revision they order/have in stock. The REV A has not been shipped from ST for some time now. Please contact your distributor and specifically ask for the right revision. 

I tried myself today (Oct 2nd) to order STM32F767Z1T6 (from Farnell), I used the chat to ask which revision it was, they informed me 4 hours later (after checking with their stock) that it was rev Z. 

Errata sheets are on line to help all our customers understand which revision of silicon is the best match for their application, and silicon revision can be obtained from your local distributor.

Laurent