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STM32L475 flash reseted

Question asked by Daniel Tarrago on Mar 6, 2018


I'm working in my own prototype that is based on the STM32L475 device.

Application is working fine: in this application, some data are saved into a reserved flash area. The problem I have found is that flash contents is lost (flash erased) when I'm in the following conditions:

In the power supply line of my board I have the possibility to plug a multimeter in series in order to measure power consumption (in the normal way - without multimeter- there is a switch that allows to feed the circuitry). When I plug the heads of the multimeter, what sometimes happens is that flash becomes reseted/erased. I suppose that this is due to the fact that when connecting multimeter heads, I cause some peaks (power supply switching) at the power supply line. Why do you think I have this behaviour?

In the same conditions (multimeter in series), when trying to flash the device via USB (Dfuse demo), the DfuseDemo tool tells me, sometimes, that device is read protected. In this case, after proceeding again, I'm able to flash the device but flash is then reseted (not preserved).

Could you give me any advice?

Best regards.