Power ESP32 via VIN pin

[rebel88]

Hello everyone,
I have developed a board to use ESP32 DEVKIT V1 as micro controller.
The board is connected to a 12V 1.8 power supply and provides 5V via 78L05 to VIN to power up the ESP32.
The ESP32 has the main aim to drive several Shift Registers and mux.
But I have a big problem.
When i connect the power supply the ESP32 start working, it initialize all peripherals but it seems that the ESP32 sends several times commands to every pheripheral. This cause a glitch on the signal that passes through multiplexers[image 1]
INSTEAD when i connect the USB cable to the ESP32 and AFTER i connect the 12V power supply the ESP32 is power on correctly and the initialize command is sent to every unit only once [image 2]
If i DISCONNECT the USB cable the ESP32 continue working correctly.
I hope i was sufficently clear in my explanation.
The problem is that i CAN'T understand why I have this strange error.
Do you have any suggestions?
Thank you.

[felmue]

Hello @rebel88

have you looked at the serial output of the ESP32? It seems like your external power supply solution cannot sustain the initial power consumption of the ESP32 and I guess ESP32 actually restarts multiple times until it steadies itself (if at all). The 78L05 is rated to provide 100mA whereas the ESP32 can easily take 300mA during startup or when WiFi is used.

You should look at a more effective power supply solution which can deliver the required amperage for the ESP32.

As a side note: using a device like the 78L05 (which is a linear voltage regulator) is not very effective to drop 12V to 5V as it will turn more energy into heat that it is delivering to the ESP32. Assuming it delivers the maximum current of 100mA, that is about 100mA x 5V = 500mW, but at the same time it turns 100mA x 7V = 700mW into heat.

I am using something like https://www.distrelec.ch/en/dc-dc-conve ... track=true for my projects.

Thanks
Felix