Hello everyone,
I am working on STM32L073RZT6 microcontroller and I have designed my custom board using this mcu. I am facing issue related to reset. The microcontroller is getting rest automatically however the period is not fixed.
I understand the possible reasons for reset as per following image
Till now I have designed 3 boards using this microcontroller and in all the cases I am facing same issue. When I programmed the microcontroller for the first time it worked for 2-3 hours continuously in one board it worked for 6 hours too and after that it started resetting.
The voltage on reset pin is varying however the supply voltage is clean, you can refer the following image.
The code that I have programmed in the MCU is simple LED blink code and also it sends data on USART5 the code is directly exported from the cube IDE and I have done very less changes I have also attached my main.c file for your reference..
I have tested following things
- There is no drop on 3.3v line and supply is clean with ripples less than 70mv (Vpp)
- There is no dry solder, I did touchup many times in all the three boards and it didn't helped.
- Connections from debugger to MCU are correct and debugger is not resetting the MCU
- Decoupling capacitors are connected near all the VCC pin and value is 0.1uF, I also changed the cap values to 4.7uF and it obviously didn't help.
- Voltage on boot pin is 0v all the time.
- 3.3v LDO is capable of providing 500mA of continuous current.
- There is no bridge or short-circuit on any pin.
- I also removed the external pull up on reset pin.
- Removed the ferrite bead and shorted the line.
I am unable to figure out what's the issue, prior to this I have designed many boards based on M0, M4 microcontroller but I never faced such issue.
I have attached images of my schematic and layout for your reference, in attached layout you will observer AVCC pin is not connected anywhere I put a jumper there as it is a single sided PCB. please let me know how can I resolve this issue.
Thank you
