Processor damaged?
Posted: Thu Feb 18, 2021 3:54 pm
Hello folks,
I need your help for some serious issues. I had two prototypes made. Unfortunately, I have routed two lanes wrong and I have fixed that with disrupting the wrong lanes and soldering thin wires on the board. The pcbs wasn't connected during this procedure. Anyway, after that I discovered one different problem per PCB that hindered my further work, and I ask you for help:
1. Problem:
The SCL lane for I2C was wrong routed. I fixed that, as described above. Unfortunately, after the repair, I figured out that the new SCL lane stayed high the whole time. The mcu cannot pull down the voltage to low. I have probed it. However, if I test the pin without a pull-up resistor and no load, the pin delivers a high and low signal correctly.
2. Problem:
The mcu becomes really hot so that you can no longer touch it. I have measured the current: 400mA at 12V. The other board only 40mA at 12V. The power rails for 3V3 and 1V0 are fine. The corresponding dc-dc converter don't get hot. The current already flows in the reset state. Currently, the mcu seems to work correcty. Anyhow, I expect that the mcu will die soon, if I don't fix the problem.
My questions to both problems:
- What could be the cause of such behaviour?
- How can I analyse the problem deeper?
- Is there any way I can fix the problem?
I need your help for some serious issues. I had two prototypes made. Unfortunately, I have routed two lanes wrong and I have fixed that with disrupting the wrong lanes and soldering thin wires on the board. The pcbs wasn't connected during this procedure. Anyway, after that I discovered one different problem per PCB that hindered my further work, and I ask you for help:
1. Problem:
The SCL lane for I2C was wrong routed. I fixed that, as described above. Unfortunately, after the repair, I figured out that the new SCL lane stayed high the whole time. The mcu cannot pull down the voltage to low. I have probed it. However, if I test the pin without a pull-up resistor and no load, the pin delivers a high and low signal correctly.
2. Problem:
The mcu becomes really hot so that you can no longer touch it. I have measured the current: 400mA at 12V. The other board only 40mA at 12V. The power rails for 3V3 and 1V0 are fine. The corresponding dc-dc converter don't get hot. The current already flows in the reset state. Currently, the mcu seems to work correcty. Anyhow, I expect that the mcu will die soon, if I don't fix the problem.
My questions to both problems:
- What could be the cause of such behaviour?
- How can I analyse the problem deeper?
- Is there any way I can fix the problem?