Issue: ESP32-S3R2 with W25Q128JV Flash – Boot Problem and Overheating

[riosh10]

I'm currently working with an ESP32-S3R2 SoC paired with a W25Q128JV external flash chip. Upon initial power-up, the device outputs garbage/junk data over the serial monitor and fails to boot into the programmed application. However, if I manually reset the controller after power-up, it starts functioning correctly and executes the programmed firmware as expected.

Additionally, I've noticed that after some time of operation, the ESP32-S3R2 chip begins to heat up more than usual.

Has anyone experienced a similar issue? What could be the possible causes for the incorrect boot behavior on power-up and the abnormal heating during runtime?

Any guidance or suggestions would be appreciated.

[Sprite]

Remove C91. Not sure what the overheating is about; are you sure your 3v3 line is stable and not accidentally 5V or something? Also, how do you define 'more than usual' in this context?

[riosh10]

Just to clarify, the capacitor C91 is connected to a regular GPIO pin, so it shouldn’t affect the boot process. I removed it and tested again, but the issue is still there.

Are you suggesting I should remove C12, which is part of the reset circuit for the MCU? Please confirm if that might be causing the problem.

I also noticed that the BOOT pin (GPIO0) shows 3.8V at power-up. Since this pin already has an internal pull-up, we added an external 10kΩ pull-up resistor as well. Could this be causing any issue?

After keeping the device powered on overnight, the board became very hot. Any advice or suggestions would be helpful.

[Sprite]

Ah sorry, I thought that was connected to GPIO0. No, C12 should stay and an extra pullup on GPIO0 should not matter. However, 3.8V there? The max voltage on an ESP32 is 3.3V. Again: what are you using to power the chip?

[riosh10]

We have tested the board with three different power supply methods:

1) A 5V 2A adapter

2) A regulated 5V supply (RPS)

3) A regulated 3.3V supply (RPS) connected directly to the J7 connector[/list]

We are using the TLV75733PDBVR voltage regulator to convert 5V to 3.3V for the ESP32-S3R2.

If any additional information is needed to help troubleshoot the issue, please let me know.

[Sprite]

Hm, it's a guess, but it might be that the 40MHz crystal is somehow oscillating on a harmonic... that'd explain the garbled serial as well as the heating up. Can you confirm C14/C16 to be correct for the crystal you picked as well as the physical board layout you're using? If you can give an oscilloscope shot of the garbled serial, that'd probably also tell us if the chip is running at a harmonic.

[riosh10]

Thank you for the suggestion.
We’ve captured oscilloscope (DSO) waveforms from the UART TX line to compare the behavior during normal operation and when junk values appear. I've attached both images:
Normal output
Junk output

Yes, we have used the recommended load capacitor values (C14 and C16) according to the crystal’s datasheet.

[Sprite]

Yes, we have used the recommended load capacitor values (C14 and C16) according to the crystal’s datasheet.

Datasheets tend to not give recommended load capacitor values as it's dependent on the capacitance of the PCB and IC it's connected to as well. Specifically what crystal are you using?

[riosh10]

Please find attached the image of the crystal part number we are using in our design.

[Sprite]

Yeah, that's the load capacitance of the crystal, which is different from the actual external capacitors you need to put in, see e.g. here for an explanation. You can assume 2pF for the ESP32 pin capacitance, and the rest of the parasitics depends on your PCB design; it would be helpful if you could also post that here.