[ST-LINK/V2 ISOL] schematic reverse engineering

[Mikeyzy]

I've been searching online about the "ST-Link V2 ISOL"'s schematics and seems like nobody has done the work for it. So I decided to do some probing on the board.
Here is my result, some components are ignored such as TVS diode and bypass caps.
If anyone else got a "ST-Link V2 ISOL", feel free to help completing the schematic. Peer review is always nice.
Still haven't quite figure out how the isolation work on some lines exactly.

[pcprogrammer]

Hi Mikeyzy,

welcome to the forum and thanks for doing this work, but it might help when you actually attach the schematic. 

[Mikeyzy]

Some how the attachments didn't go through.
I'll try again.

[pcprogrammer]

I looked at the schematic and with the labels and the not inline placing of the components it is hard to read.

An improvement would be to rotate the isolators and use wires to connect them to the other components instead of the net labels. Place the MCU with the USB connector at the left and work the signals to the right with the jtag connector on the right end of the sheet.

You can use text to label the signals next to the wires.

This exercise might even clear thing up for yourself to get a better understanding of what is doing what.

[Mikeyzy]

The schematic was draw so the component positioning resembles how it's located on the PCB, for probing and mapping purpose. Unfortunately eagle being the way it is, there is no way to do directional signal label/tunnel.

[pcprogrammer]

Can you post pictures of the PCB, both back and front. Would be nice to see what matches the schematic.

[Mikeyzy]

files are compressed so they fit the max size.

[Mikeyzy]

somehow when I upload attachment, some of them doesn't go through.

[DavidAlfa]

Really? The couldn't use a smaller crystal? 

[pcprogrammer]

somehow when I upload attachment, some of them doesn't go through.

Recently the uploading system has been updated and that broke it. Don't use the drag and drop feature and skip the first attachment option. Click the "more attachments" option and use the new one(s) to select your file(s).

Also keep the default End-of-post expandable thumbnail option selected. The rest does not work as intended.

Thanks for the photos.

Can you identify the big part near the USB connection? Is it a Burr and Brown device?

[wek]

It's a DC/DC converter providing power to the isolated side.

JW

[Mikeyzy]

the big dip smd part is a expensive TI isolated votage regulator/PS. power section isn't as important since it is easy to figure out. the main concern is on the logic isolation side.

[gwideman]

@Mikeyzy  Would you mind reposting the schematic PDF? The forum software seems to have messed up the connection between attachment links and actual files so that the link "ST-Link-V2-ISOL.pdf (41.75 kB..." actually retrieves the JPG of the rear of the board, just misnamed  ST-Link-V2-ISOL.pdf.
Your effort in tracing this schematic is very welcome, by the way! Thanks!

[DavidAlfa]

That's actually a jpg... the full-sized picture of the pcb bottom.
Seems like he renamed and uploaded the wrong file in first place.

[pcprogrammer]

Mikeyzy has not been on the forum for a long time, so the chance of them reading this is very small. Maybe a personal message can wake them up.

Edit: corrected some spelling.

[coromonadalix]

can this help

[tooki]

That's actually a jpg... the full-sized picture of the pcb bottom.
Seems like he renamed and uploaded the wrong file in first place.

Nope, there was an issue with the database that caused file contents to be associated incorrectly.

[gwideman]

can this help

Thanks for contributing, but this doesn't really help. That JPG is readily downloadable in a previous message.  This is not the schematic, it is the schematic with the entire MCU section overlayed by a picture of the PCB, hence obscuring the heart of the schematic.

[gwideman]

That's actually a jpg... the full-sized picture of the pcb bottom.
Seems like he renamed and uploaded the wrong file in first place.

Thanks for replying, but I'm not sure your point. Are you saying something different than what I wrote?

[voltsandjolts]

Wayback machine saves the day...
but it's one of those "schematics" without wires!

[gwideman]

Wayback machine saves the day...
but it's one of those "schematics" without wires!

Well done! The style in which connections are mostly implemented by labels rather than explicit lines probably stems from the original poster's goal of positioning components corresponding to their location on the PCB, to ease the task of tracing the circuit, so fair enough. It is helpful that the labels are captured in the PDF, so you can use the search function to find matching labels if you need to.

Thanks for going to the effort of fetching this file!

[peter-h]

Sorry to say this but what is the point?

ST are likely to detect a fake STLINK and stop it running. And the real ones cost basically almost nothing.

[voltsandjolts]

And the real ones cost basically almost nothing.

Not true for the isolated versions, which are the subject of this thread.
But a standard STLink plus a cheap USB iso should do much the same job I would have thought?

[peter-h]

The STLINK V2 ISOL also costs practically nothing.

I don't "like" STM any more than a lot of people but counterfeiting this dirt cheap stuff is just a waste of time.

The ISOL debugger reduces chances of blowing up a target (or the PC) but the scenarios where that applies are rare, given that the two are normally in very close proximity. If they were say 100m apart and on different mains supplies, that would be different. I've been selling non-isolated and isolated 232-4XX converter for 30 years and there is a big difference in the blow-up rate.

They also run significantly slower, especially for the SWV ITM debug feature. So if I was building a better one, I would use the RF-coupled isolators (e.g. SI8641BB) which are much faster than traditional optoisolators (unless the latter are running at high power).

[voltsandjolts]

The STLINK V2 ISOL also costs practically nothing.

£60 + VAT

Perhaps it's a hobbyist vs commercial thing.
To me a Segger J-Link is practically nothing, yet some folks doing commercial work are too grippy to buy a genuine one.