Why do newer STLINK V2/ISOL display a lower voltage than older ones?' Why does new hardware look different and works different

[TDamm.1]

We have already received 2 deliveries of STLINK V2/ISOL from well-known suppliers, which display a lower voltage and also partly do not work with our products.

Unfortunately, we have not yet received an answer from support and currently do not know how to go on after the second delivery of hardware with that problem

Can someone from the community check the displayed voltage and confirm here that possibly the identical problem exists with him?

The new hardware also looks different

Translated with DeepL

[Peter BENSCH]

Welcome, @TDamm.1​, to the community!

Official statement: the ST-LINK/V2 ISOL is not a calibrated and certified measuring device, nor is a maximum tolerance specified in the documentation. The measured target voltage is for orientation only and may well deviate.

Practical suggestion: the actual analogue front end is formed by the components U15, U16 and U17, with U16 (LOC110) mirroring the measuring current by a coupling factor called K3. Although this coupling factor is extremely linear, it depends on the particular bin. Unfortunately, the bins of K3 of the LOC110 are decisive for the measured value, but are not explicitly orderable. Bin F now has a lower coupling factor (K3) than bin G, which could explain the smaller reading.

You can now either determine the (probably constant) factor of the deviation and later numerically correct the measurement results of the respective ST-LINK/V2 ISOL accordingly, or you calibrate the front end yourself. For calibration, you can adjust one of the two resistors (with the same factor as the deviation):

• either R33 (33k, between CN3.1 and U15, decreasing R33 increases the measured value),
• or R32 (33k, between U17 and U16, increasing R32 increases the measured value)

Hope that helps?

Good luck!

Regards

/Peter

[TDamm.1]

Hello Peter,

two questions.

a.) Do you have a schematic and a layout?

How I can I find the devices which you mention (for example R32)

b.) Our Problem is not the wrong voltages which is displayed.

Our problem is that we can program one board with the old model (green) and not with the new model (red).

The board have a special situation - the powersuplly is 3V0 and not 3V3

[Peter BENSCH]

A) Circuit and layout are internal information.

However, you can find both resistors very easily: R32 is between U16.5 (LOC110) and GND, located as mentioned directly between U16 and U17 near U16.6/U16.7. R33 can be found directly at the notch of the PCB at pin 1 of connector CN3 (your red wire is plugged into pin 2).

B) The programming problem was not clear from your description. However, it should have nothing to do with the target voltage of 3V, as the ST-LINK/V2 are specified for the voltage range 1.65-3.6V. Can the new model not program a target board at all, or only one specific variant?

Regards

/Peter

[TDamm.1]

We use the programmer for several boards.

The most boards are working but in a special case (Board is powered only 3V0 and we have to supply 3V0 externally to the VCC Pin from the programmer because we have no contact to board) it is working with old programmers but not with new programmers.

It seems there was a change which cause the problems in the programmer HW (The hardware looks different - see my attachments)

[Peter BENSCH]

The schmematic has not changed, only some components have been replaced by equivalents, which is permissible within the scope of the data brief:

STMicroelectronics NV and its subsidiaries ("ST") reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice.

But you could now investigate what error messages the STM32Cube programmer reports and what is happening on the lines, i.e. the JTAG or SWD lines, compared to the functioning ST-LINK. However, an error analysis from a distance without the corresponding details is a little difficult and not really the aim of the community. If necessary, contact an FAE in your region or the nearest ST office?

Regards

/Peter

[TDamm.1]

Hi Peter,

thank you very much for your help.

My colleague pulled an official Suport ticket and got no response. 

At some point, the ticket was simply closed...

I will pass your answers on to him and ask him to contact you again when he has the structure so that he can reproduce it next week - he is currently on vacation.