Hi, I am using STM32F103RCT6 in a project. These project make power test fail. More specific, when we power OFF the device and power ON again, if the power ON occurs when voltage is ~1V then the uC is not working.

[AAlas.1134]

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[waclawek.jan]

The 'F1 family is relatively old and I don't use it. Does it have a brownout detection option in the Option Bytes? If yes, switch it on. If not, you might need an external voltage supervisor/reset chip; or move to a more modern STM32 which does have brownout detection.

JW

PS. Please change your username to a normal nick

[AAlas.1134]

Thank you for the comment, if ı misunderstood, F1 family doesn't have brownout detection.

[Tesla DeLorean]

Use better POR circuit that doesn't use capacitors, but rather a laser tried thresholding​ device which will clamp NRST low for a 100 ms, or more, after VDD hits 3V or whatever.

[AAlas.1134]

Thank you for the comment, Could you explain why I don't have to use capacitors.

[waclawek.jan]

> why I don't have to use capacitors.

RC resets fail to produce a clean reset signal unless VDD rises and falls fast enough and falls low enough.

This is an older writep on the topic, 8051-specific so it talks about positive reset (which is a 8051-specific quirk and does not apply on STM32, which has the usual negative reset). There may be similar or better writeups out there on the issue of reset, brownout, etc.

JW

 PS. Oh, 8052.com is now 8052mcu.com, although it's mostly dead, but some of the old content is still there.