Bad usb cable horror - please add warning to docs & getting & started

[thomas0099]

Hi,

I have been through a week of testing, retesting, trying again, endless frustration, lots of unexplainable errors like reboots, WIFI examples not working, working sometimes, esptool unexpectably faulting, flash errors, whatever you want, I've seen it.
Even bought a new usb hub, because it might be the power...

I was close to sending the modules back an stay with esp8266.

Last thing I tried, was change the usb cable to the one my son used on his android phone.
I had seen some articles describing different errors and said to myself: Can't be that simple, cable is working, I have a connection...

So Please, please,please: Place a big fat

WARNING: USE A GOOD CABLE THAT IS GOOD TO CARRY ENOUGH VOLTAGE

on as much places you like.

[pontificator]

ESP-32 consumes a lot of current while transmitting. I saw spikes of 0.7A with duration of 0.5 ms. If you have USB cable with resistance of about 2 Ohm, then those spikes might cause reset.

Use a 1000 uF capacitor across +3.3V rail. After that it should work with any USB cable.

I saw those 0.7A spikes on ESP-WROOM-32 module marked with white letter 'C' at the antenna area. When I tested ESP-WROOM-32 marked with letter 'K', the spikes where below 0.3A.

However, module 'K' has much worse sensitivity. It can see only 1-2 WiFi networks where module 'C' can see 5-10 networks. BTW, module ESP-12F can see up to 20 networks in the same conditions.