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ESP SMD Breakout Serial Monitor Interference

Posted: Fri Jan 08, 2021 10:47 am
by amoghjain

In my current electrical setup (see attached picture) : I have an
- ESP32 SMD module on a breakout board
- Breakout board is connected to Ubuntu using ESP-Prog's FTDI to UART converter.
- esp32 is connected to WiFi using my phone's hotspot and makes a post every 5 mins.
- another esp DevBoard Module connected to esp breakout board via ESP-Now.

Additionally, previously, I was busting the esp's as I wasnt using any ESD protection, and none of the modules would last more than a couple hours, but now I am using inside of esd shipping packets on my desk, and a esd mat on my soldering desk and both of these are grounded, and have not yet, touched the esp without esd free gloves, and without a grounding strap connected to my arm, so atleast I am positive this problem is not related to esd on esp.

What I have been observing on this new latest board for over 2 days now is,

- random serial characters appear on the serial monitor
- serial monitor stops responding ie doenst show any movement
- Serial starts normally after a while
- Oscilloscope shows peak to peak voltage ripple of 39mV.
but few minutes later, all just goes back to normal.

I can confirm the smd ESP working
- i can send a blink command from wifi to esp on breakout board, which sends command to another esp on devboard and blinks the led.
- esp on breakout board is making regular posts, every 5 mins, and none of them are missing
- I can see esp-prog receive led blink blue, but yet my Ubuntu's serial monitor shows nothing(or just freezes.)

My PCB design is almost done and I am going to order a few soon to confirm this is not some sort of wiring interference/noise. All indications point to some form of noise, corrupting the serial, but since, esp is sending/and recieving the data just fine, I am coming to believe that theres a fault in serial procesing of my laptop, an 8 year old lenovo T530, but since I am not an expert in serial/electronics, I was hoping I could get some insights of the potential issues, or some guidance on what I am try/troubleshoot.