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mahjongg
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Re: Full schematic for the Pi3 and Zero

Fri Mar 16, 2018 11:25 am

I think that when, in a few weeks, the PoE HAT is launched a lot more documentation will be released.
The main change in the PI3B+ for PoE is that a new magjack is used, which has connector pins enabling the routing out of the signals needed for power transmission over the RJ-45 cable, so connections to the RJ-45 wiring -before- the Ethernet transformer are now routed out, of the new magjack, that is the main change that was needed to make PoE possible with a simple wiring interface.

hippy
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Re: Full schematic for the Pi3 and Zero

Sat Mar 17, 2018 9:28 pm

mahjongg wrote:
Wed Mar 14, 2018 6:18 pm
What about the documentation Microchip (the makers of the LAN7515) provide? You can get it from them, here: http://www.microchip.com/wwwproducts/Pr ... 15/LAN9514, should be enough to modify your design.
Following the LAN7515 link from that page takes one to a generic Microchip home page, which provides no details on the LAN7515. The LAN9514 link works as one would expect.

I and others have been looking for an actual LAN7515 datasheet but nothing has turned up yet. Someone here reported that it had been asked about on the Microchip forums but I could find no sign of that, so either it wasn't, those posts have disappeared, or are not appearing in search results. And I couldn't find them when manually checking forum posts.

Edit: BobKruse above. Seems I was reading page 1 thinking that was the last and latest page of the thread :oops: Perhaps BobKruse could update us on his post to the forum.

Though Microchip say the chip is in production, it is not available for on-line purchase, and although references to LAN7515 do turn up in search results, none of the pages or documents linked to which I followed actuallyreference the LAN7515. Search results suggest it was known about in June 2017 so it is all rather odd.

The only page which appears to give any detail on the LAN7515 is the comparison page pointed to, and that just gives headline specs, certainly not enough to allow a design using it to be developed.

BobKruse
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Re: Full schematic for the Pi3 and Zero

Fri Mar 30, 2018 1:58 pm

Hello,

The official answer about the LAN7515 chip from Microchip came this morning:
"Hello,

I have received a message from the Business Unit:
“This part was a specialized part for Raspberry Pi, so the information is not publicly available.
For more information, they would need to go through the Sales channel (who will contact Ian Saturley, the marketer for this part).

If they are looking for other options, they can look at the LAN951x (not a GigE PHY, but with USB2, you don't use GigE bandwidth anyway), or a USB2517 + LAN7850 to get more USB ports.”

Please contact our Sales department at:
www.microchip.com/sales
Do not confuse the sales department from this link with Microchip Direct. Are not one and the same.

Regards,
"

hippy
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Re: Full schematic for the Pi3 and Zero

Fri Mar 30, 2018 3:29 pm

BobKruse wrote:
Fri Mar 30, 2018 1:58 pm
"This part was a specialized part for Raspberry Pi, so the information is not publicly available.
For more information, they would need to go through the Sales channel (who will contact Ian Saturley, the marketer for this part)"
Many thanks for the update which confirms how it had been speculated to be.

I suppose the next step, if one wants the information, is to follow the steps Microchip indicate. It wouldn't surprise me if any release of detailed LAN7515 information comes with an NDA or similar public dissemination restrictions but one would only know for sure if someone asked for it.

The situation doesn't greatly affect anyone here, other than potentially offending their desire for openness. It may be more of an issue for those competing with the Pi or hoping to add a LAN7515 to their own products but that would be an issue they would have to deal with if there is.

jamesh
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Re: Full schematic for the Pi3 and Zero

Fri Mar 30, 2018 5:47 pm

Whilst I do not believe a datasheet is available, this driver used under linux is the lan78xx, which is compatible with a number of different products, so I suspect a lot could be gleaned from that.
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hippy
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Re: Full schematic for the Pi3 and Zero

Fri Mar 30, 2018 10:12 pm

jamesh wrote:
Fri Mar 30, 2018 5:47 pm
Whilst I do not believe a datasheet is available, this driver used under linux is the lan78xx, which is compatible with a number of different products, so I suspect a lot could be gleaned from that.
I would agree with that. From what we do know about the LAN7515, how it presents itself, the parts we know Microchip have, the potential for putting things together in a single package, there is probably not a lot in a datasheet which would be useful or interesting for most Pi users.

For me it was more intrigue as to why Microchip were doing things the way they had, what lay behind that, their motivation for behaving in such an unusual way. Intrigue as to what is being kept hidden from us.

I guess, any time someone hides something when there seems no good reason to do that, I'm naturally inclined to want to know why.

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Gavinmc42
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Re: Full schematic for the Pi3 and Zero

Fri Mar 30, 2018 11:27 pm

Broadcom doing a mirror die and new packaging, microchip doing a custom Lan part.
Incomplete schematics - but it is so far a 20Million part market with no signs of slowing.
Potentially 100's of million of parts? Well chip makers will try to keep a customer like that on board.

RPF have made it into the big time, do not expect any sudden revelations and release of information.
This is a market nobody wants to rock the boat on, except some very keen Chinese?
However even the Chinese like profit, how many other SBC's have same or lower pricing?
How many have the Education support that is RPF Mission?
If it does not help the Mission it is not that important to RPF to release information.

Wonder what the Chinese education system is doing?
They have the capacity to make Pi equivalents, perhaps with Allwinner chips.
They have a language issue which could cause issues as most(all) code is written in English.
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rickticktock
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Re: Full schematic for the Pi3 and Zero

Tue Sep 25, 2018 4:09 pm

I've just bricked my Pi 3 B+ because of a short, 3.3 to GND, on a breadboard I had connected :( . I was wondering if pruning out a 3-terminal regulator and feeding 3.3V back in through the GPIO would work. Red LED lights, green doesn't. A schematic would be useful!
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DirkS
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Re: Full schematic for the Pi3 and Zero

Tue Sep 25, 2018 4:18 pm

rickticktock wrote:
Tue Sep 25, 2018 4:09 pm
I've just bricked my Pi 3 B+ because of a short, 3.3 to GND, on a breadboard I had connected :( . I was wondering if pruning out a 3-terminal regulator and feeding 3.3V back in through the GPIO would work. Red LED lights, green doesn't. A schematic would be useful!
That's not bricking, but frying a Pi. If your Pi gets hot very quickly then it's at the end of its useful life. A schematic will not help you with that.

rickticktock
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Re: Full schematic for the Pi3 and Zero

Tue Sep 25, 2018 4:47 pm

Hi Dirk,
It didn't get at all hot, it just died. The MXL7704 quad power supply features over-current protection so I'm surprised it did not resurrect without the faulty breadboard connected.
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hippy
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Re: Full schematic for the Pi3 and Zero

Tue Sep 25, 2018 5:12 pm

rickticktock wrote:
Tue Sep 25, 2018 4:47 pm
The MXL7704 quad power supply features over-current protection so I'm surprised it did not resurrect without the faulty breadboard connected.
You are not the only one. Why the MxL7704 bricks itself and remains bricked has not so far been explained but it appears to be the way it is with other reports of the same -

https://www.raspberrypi.org/forums/view ... 8&t=218610

My theory is the MxL7704 is somehow losing its programmable memory when it shuts down, then cannot bring the SoC up when it is re-powered. I have absolutely nothing to back that up but it would explain why replacing the MxL7704 has allowed the Pi to boot again at least in one reported case.
rickticktock wrote:
Tue Sep 25, 2018 4:09 pm
I was wondering if pruning out a 3-terminal regulator and feeding 3.3V back in through the GPIO would work.
Won't work. You would need to provide all the other voltages the MxL7704 delivers and probably remove the MxL7704 itself. And that might cause issues when the SoC cannot communicate with it.

rickticktock
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Re: Full schematic for the Pi3 and Zero

Tue Sep 25, 2018 8:44 pm

I could prune the appropriate inductor on the output of the 3V3 regulator. First, I will check all the regulator outputs to see which, if any, still work.

hippy
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Re: Full schematic for the Pi3 and Zero

Wed Sep 26, 2018 8:43 am

rickticktock wrote:
Tue Sep 25, 2018 8:44 pm
First, I will check all the regulator outputs to see which, if any, still work.
The challenge with the MxL7704 is that it appears to be all or nothing by design.

rickticktock
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Re: Full schematic for the Pi3 and Zero

Wed Sep 26, 2018 9:09 am

Hippy, I think you're right. None of the 4 SMPS outputs had any voltage. The DVM readings floated about at a few mV, implying open circuits. Also, it seems that order of bringing up the power rails is important so even connecting a bunch of bench power supplies won't do. I've binned it and ordered a new Pi. :cry: . Here's another thing, I'm not sure there was a short on the breadboard as such, but I have a few 0.47uF capacitors strewn around the power rails because there's a load of 74HCTxx clacking away. Average power would be very low, but transient currents could be high. Perhaps the charging current is what killed it. Anyway, moral is don't power off the GPIO, use the bench power supply.
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rickticktock

digger72
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Re: Full schematic for the Pi3 and Zero

Wed Mar 20, 2019 3:11 am

Some description of the Raspberry Pi Zero W hardware and Schematics details are here - https://www.youtube.com/watch?v=oq7JKRsrX-0

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