Problem: Normal operation, sudden crash. Re-power failure remains
Appearance:
The normal operation of MCU STM32F407ZET6 will output a 20MHz reference clock to CPLD, but the oscilloscope detection and CPLD condition detection confirm that MCU has no output signal.
The SPI control digital screen of MCU STM32F407ZET6 also does not work properly.
Location: MCU does not start up normally.
Detection: 1. Pin144 - GND: 3. 326V of STM32F407ZET6 is normal!
2. External crystal oscillator 10MHz: starting condition: oscilloscope detection PIN-23 - > crystal oscillator does not oscillate. Normal circuit boards can boost. ABA experiments on crystal oscillator and peripheral capacitance have been carried out to verify that there are no problems related to crystal oscillator and capacitance. Location is caused by internal problems of STM32F407ZET6.
Crystal oscillator can not start normally.
3. The BOOT0 PIN138:0V of STM32F407ZET6 has normal connection with GND.
4. The ABA experiment of STM32F407ZET6 proves that the problem of bad STM32F407ZET6 film exists.
5. Simulator Connection Experiments:
5.1 Without checking, the software prompt can erase FLASH and burn chips, but the program just can't run. Nor can DEBUG be online.
5.2 Check the case: Software prompt can erase FLASH failure:
6. Need to apply for invalidation analysis, thank you!
