Issue Connecting STM32H745BIT6 Custom Board with STLINK-V3SET Debugger

[Prathiksha]

Hi Team,

We are currently working with a custom board that uses the STM32H745BIT6 MCU, and we are attempting to connect it to the STLINK-V3SET debugger. However, we are experiencing intermittent debugging issues described below:

1. The debugger successfully enters debug mode only 2–3 times when done the first time.

2. In most cases, the debugger connects and enters debug mode, but after approximately 6–8 seconds, it displays a “Target lost” error (please refer to the attached photo).

3. Often, it shows “Target not responding.” When this happens, we need to power cycle the board. After turning the power supply off and on again, it behaves as described in point 2.

This issue has become a major roadblock in our development process.

Could you please advise if we might be missing something or configuring anything incorrectly? If you require any additional information from our side (errors, logs, etc.), please let us know and we will provide it.

Best regards,
Prathiksha

[mƎALLEm]

Hello,

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@Prathiksha wrote:

Could you also confirm whether any specific software configuration or initialization is required to enable the SMPS output?

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Please use CubeMx tool to generate the code that reflects this configuration.

Thar reflects the following hardware configuration provided in the reference manual (RM0399):

[Prathiksha]

Yes. I have tried the same configuration.

Neither that nor LDO supply, we are not able to dump the code.

[mƎALLEm]

The schematic you shared previously seems to tell that the power supply is in SMPS mode.

Hard to follow the connections in that schematic (bad rendering of the wires). I suggest you to get back to your hardware guy that has drawn that schematic and check again the hardware according to that what is shown in the reference manual Figure 22.

[TDK]

Maybe the hardware team can also explain why it's not working then.

[Prathiksha]

Hi,

Today's observation is that one of our boards worked with some changes with clock configuration.
Mainly changed PLL Source Mux from HSI to HSE and some frequency changes accordingly. (attached is the screenshot).
but same configuration it's not working with other boards.

Could you please explain.

[mƎALLEm]

Hello,

No I cannot explain based on the information available. You need to check again your hardware. It could be also an issue with your PCB.

HSI is not working but HSE is working is a bit strange. Based on your HSE config you seem to be using an external Crystal oscillator (XO) and not a crystal (XTAL). You need to check also this part.

But again you need to check with your hardware team the power schematics based on the Figure 22 provided in the reference manual.

[Prathiksha]

Hi Team,

We have connected the hardware as per Direct SMPS Method with two numbers of 2.2nF capacitors at Vcap pin of the MCU. With this, we observed lot of ripple in the Vcap voltage and also observed Vcap dropping to below 0.65V and again recovering back. This was repeating a lot when board is just in Powered on condition.

However, we soldered a 4.7uF capacitor to Vcap pin and after that observed lesser ripple. We did not see the Vcap drop to 0.65V and all. Vcap was stable at this point of time. We properly observed Vcap rising to 1.2V at Power on and then staying at 1V till the board is in On condition. This is as per the Power On sequence from the STM32H745 reference manual Page 278.

With this setup, we programmed the board with DIRECT SMPS SUPPLY and VOS1 in the .ioc file. 

When we programmed, we observe the following sequence.

1) Program memory erased.

2) We entered the Debug mode for 2 seconds.

3) Then it showed Target lost.

When we checked Vcap, it is showing some 100mV value. With thi, we are observing that the Vcap voltage is going to 1.2V after power on but then falling to 100mV and staying there.

Please suggest us where we are going wrong and help us in solving this "Target lost" issue.

[mƎALLEm]

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@Prathiksha wrote:

When we checked Vcap, it is showing some 100mV value. With thi, we are observing that the Vcap voltage is going to 1.2V after power on but then falling to 100mV and staying there. 

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That's a hardware issue. I cannot determine what it is. As I said previously: check again your hardware. It could be also an issue with your PCB: solder joint issue, routing issue? I don't know ..