ESP32 Forum

My electronics skills are low but I think this is a meaningful question. The DevKitC has a 5V output pin which I am presuming is connected to the on-board USB. How much current can I draw from the 5V pin?

Back story ... I am attempting to drive an HC-SR04 ultrasonic transmitter/receiver which is a 5V device. I am powering it from the 5V/GND pair on a DevKitC and things aren't working as I would imagine. Working through the list of possibilities, I am considering the notion that the current supplied to the HC-SR04 may not be enough ... hence the question.

Depends on what is the USB power source. For a PC port probably 500mA total, shared with 3.3v LDO. Looks like HC-SR04 only uses <20mA, so should be OK. Might need some additional decoupling caps? Might need 3.3v to 5v level shifting?

Thank you again for the response. I found the problem with my HC-SR04 connection. The DevKitC getting started guide has a pin labeled GND in the diagram (the pin just north of 5V). However when we look at the actual board (using a magnifying glass), the pin is actually labeled "CMD" and not "GND" ... and I can now attest ... it isn't GND. This was a naughty problem and I hope we can get the DevKitC documentation PDF (this version 1.0) updated quickly cause this one could hurt one's ESP32.