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Muhammed Güler
Muhammed Güler
Senior III
February 24, 2020
Question

debug breaks when the relays operate. The system continues to run

  • February 24, 2020
  • 2 replies
  • 674 views

I design a PCB with a stm32f407.

Relays come into play shortly after debug starts. sometimes the debug fails and closes when the relay activates. What should I do to prevent the debug from closing?

relays are driven with 24 volts and lm2803.

The st link is connected to the processor by serial wire.

I tried with clone stlink V2 and Stlink V3.

This topic has been closed for replies.

2 replies

Uwe Bonnes
Uwe Bonnes
Chief
February 24, 2020

This is EMI, electromagnetic interference. Rething your wiring, try to keep relay and signal line apart and also think where switching current flow and iof switching shifts your grounds.

Ozone
Ozone
Principal
February 24, 2020

Proper decoupling of the MCU power supply from the 24V supply line, proper back EMF suppression near the relay coils, and the driving MCU ouputs.

Optimally, as little intersection of the relay section with the MCU section on the PCB.

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