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STM32 chip detection issue while flashing

KGand.1
Associate

‎2020-08-23 09:26 PM

Hi STM Team,

We are trying to flash code to STM32H745 through SWD interface. However, after multiple flashing cycles to STM, we unable to detect device in 2 or 3 boards.The below are list of the observations of that scenario.

  • Once we give 3.3V supply to STM and we are not connecting ST-Link V2 programmer in this case, STM32 able to generate 1.2V supply through internal DC-DC converter from the output as per below image.

0693W000003Q4QCQA0.jpg

  • Once we provide 3.3V supply to STM and connecting SWCLK,SWDIO and NRST signal to the programmer in this case, STM32 does not able to generate 1.2V signal from DC-DC instead we are getting approximately 0.044V and same 0.044V remains as it is after disconnecting programmer as well.
  • In the by default state after powering on STM(without programmer connection), NRST signal voltage level is approximately 1.4V.
  • After powering on STM and after connecting programmer connections, NRST signal voltage level is approximately 3.3V.
  • Snapshot of the error message which we are getting in this scenario.

0693W000003Q4QMQA0.jpg

  • We have verified all the debugger connections one to one and all those connections looks ok with the continuity check.
  • We have tried to replace STM32 chip and then it was working fine but after few time again, we are observing same behavior with the new chip as well.

We have interfaced STM32H745 with various basic peripherals like SPI,I2C, UART etc and additionally it is also connected with other microcontroller of Mediatek over SPI as well.

Regards,

Krushang Gandhi

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M.Hajji
Associate III

‎2020-08-26 05:47 PM

Hello KGand.1,

Here what I suggest to look into for this issue:

  • Do you have a good grounding for the device and programmer (Both GND connected)?
  • Cap ( from C132 to C141) how are they connected ? I suggest to look at AN4938. too much capacity will not help the DC-DC starting, not enough capacity and the DC-DC will not be stable.
  • Maybe there is a mis-configuration in the PWR register, the board is designed for SMPS but it got disabled by software.
    • Try to hold reset, power on the device and then connect the programmer (release reset as you press connect) also make sure that you are connecting under reset and hardware reset in Cube Programmer. this way you will connect before any software PWR configuration.
    • Do you know the last software loaded before this behavior seen ?
  • Can you connect via bootloader ?
  • Can you capture the power on sequence of VDD, VCAPs, NRST, with an oscilloscope (with ST-Link connected and disconnected).

Hope these suggestions help.

Regards,

Hajji.

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