Is the electrical schematic of STM32F746G-DISCO is changed w.r.t. legacy STM32F746G-DISCO?

[SKhol]

We have developed an application with legacy STM32F746G-DISCO.

Recently we purchased more STM32F746G-DISCO.

Although newly purchased STM32F746G-DISCO looks exactly same there are few changes as below

-1 The color of leaflet is Yellow ( vs sky-blue )

-2 CN6 Pin 1 was NC ( reserved ) earlier. Now its 5V

-3 Pin 5 & 6 of CN5 were earlier PF7, PF6 respectively. Now they are PF7/PB9 , PF6/PB8

-4 Pin 8 of CN7 was AVDD earlier now its AVDD/+VREF

We tried searching new schematics for STM32F746G-DISCO. But they are no where available.

Kindly suggest how to obtain the new schematics for new STM32F746G-DISCO along with its version history.

I have attached the leaflet comparison of old vs new leaflet pin map for comparison.

[waclawek.jan]

Which board revision do you have (there is a description or a sticker on the board somewhere)?

At https://www.st.com/en/evaluation-tools/32f746gdiscovery.html#cad-resources under CAD Resources, there are schematics for rev.B02 and rev.C01.

ST, please update UM1907 with the differences between revisions.

JW

@Amel NASRI​ 

[Amel NASRI]

Hi @Community member​ ,

Request to update UM1907 is tracked.

Internal ticket number: 133387 (This is an internal tracking number and is not accessible or usable by customers).

-Amel

[waclawek.jan]

Thanks, Amel.

Jan

[Uwe Bonnes]

Find the schematics of revision B and C at https://www.st.com/en/evaluation-tools/32f746gdiscovery.html#cad-resources . I guess you have an old revision of dm00190424 with the schematic of Rev. 1

[waclawek.jan]

Hi @Uwe Bonnes​ ,

what is dm00190424, is it UM1907?

My UM1907 DocID027942 Rev 1 indicates on schematics that they belong to board rev.B-02.

JW

[Peter BENSCH]

Well, the only real difference I can see is CN6.1, which is now marked E5V. I don't currently have the version, but @SKhol​ should be able to measure it quite quickly.

The other differences are not real differences, but only clarifications of the labelling, as these pins could also be switched alternatively by solder bridge before.

That leaves the colour scheme: STMicroelectronics recently changed the general colour scheme and the leaflet simply follows suit.

Finally, may I once again refer to the Terms of Use, because the question gives the impression that the DISCOVERY are being used improperly for an end product.

@Community member​ yes, DM00190424 is a previously used alternative number to UM1907.

Regards

/Peter

[Tesla DeLorean]

Didn't the screen make / model / sourcing change?

It's been a while. Seem to remember at least some of the DISCOs have subtle pin errors in either the code, inserts, or the schematic. These may have be remedied in the 5-6 years, or whatever, the boards have been produced.

I would look in the BSP files of CubeF7, ST has been reasonably good in identifying board revision and pin changes,and switching those via command line defines to the compiler. Also calling out these things in Project README.TXT files.

The boards evolve, component level availability changes over the span of multiple years, as vendors move with the consumer product cycles measured in quarters

[waclawek.jan]

> Didn't the screen make / model / sourcing change?

That, plus the memories, MEMS, and a couple of lesser interesting things.

https://community.st.com/s/question/0D53W000006GqWWSA0/32f746gdiscovery-b02-and-c01-whats-the-difference

I can't see difference in CN6.1 in the schematics, though.

JW

[Tesla DeLorean]

In the RevB board VDDA = +VREF, via single ohm, don't think that's different, just nomenclature

There is an option to route I2C to A4/A5 to match one, or more, of the Arduino designs (MEGA/DUE ?), and actually D14/D15 A4/A5 for I2C is common on several boards. So basically accommodative of shields assuming I2C here rather than analogue

On the STM32F746G it is achieved via Solder Bridges.

SB1 PB8

SB3 PF6 (Default)

SB4 PB9

SB5 PF7 (Default)

The pin North of IOREF is not connected, not sure when that occurred, or how consequential that is.

Attaching Rev1 from my repository/mirror, look to have 3,4,5 immediately to hand on the current box

[SKhol]

@Community member​ 

Thanks for suggestion.

I think your suggestion will solve my issue as I am facing issue with I2C functionality.

My firmware does work very well with old board & with new board it doest work just because of I2C error.

I will dry breaking default solder bridges & manually shorting other two.

[SKhol]

Dear All,

I tried changing solder bridges by making below connecytions

SB1 PB8- SHORT

SB3 PF6 (OPEN)

SB4 PB9 - SHORT

SB5 PF7 (OPEN)

Still no luck. The test firmware still not working with new board & its perfectly working with old board.

For more information, I am attaching comparison of marking labels on New Vs Old DISCO board.

Please suggest

[Tesla DeLorean]

They both claim to be C01 revision boards

Expect you'll need to debug the code, understand the specific issues there, and then relate those to the circuit as you trace it out, and compare to the schematic

[Piranha]

What makes you so sure the problem is not in the firmware? The fact that it's working on the older board, still doesn't prove anything. Does it use HAL/Cube code? If so, it's broken!

[SKhol]

If I flash the same firmware in 2 boards ( 1 new , 1 old ) and test one by one, old one works and new board doesn't so its obvious that only change is the new board

[Tesla DeLorean]

Could be a component or BOM level issue.

​

H​owever "not working" is hard to diagnose without more specific detail.

​

Don't you have the source, can't you debug or instrument to focus on the specific reason for failure?