Wifi Kit 32 power from 5V pin

#1

Hi,

I am using a Heltec Wifi Kit 32 to control a servo motor. All is working fine when the ESP is powered via USB and the servo attached to the 5V pin.
Now I am trying to power the ESP and Servo from an external 5V 6A PSU and not through USB.

This causes the ESP to reboot when the Servo is moving fast. I assume the voltage drops to much.

I had a look at the Heltec Wifi Kit 32 schematics, and it appears the USB 5V and 5V pin are directly connected. Any idea why the higher rated PSU can’t power both servo and ESP?

Regards
Andreas

#2

Update: I compared the Wifi Kit 32 and New Wifi Kit 32 schematics.
The New Wifi Kit 32 shows a 500mA fuse between USB and +5V, the original design lacks this fuse.

Is this fuse likely to blow when I power the Wifi Kit 32 through USB and drive a servo with >1.5A via the +5V pin?

#3

Since you have a 6A supply available, you should probably supply the servo power directly from that source through individual fuses. Look for a polyfuse rated appropriately for the draw of each servo so that it will self reset. Note that you still should supply buffering capacitors for each servo in addition to your capacitor buffering the WiFi32 board.

#4

Hi Chibi, the point is that the Wifi Kit reboots when supplied from the 6A PSU via the +5V pin, but not when powered via USB.

The Wifi Kit 32 datasheet specs the 5V output current as “equal to the input current”
5V Header output (USB powered only) Equal to the input current

But the schematics show a 500mA fuse between USB and the 5V pin.

Is the 5V pin limited to 500mA by this fuse on the New Wifi Kit 32?

#5

I would have no idea about the internal design of the WiFi Kit 32, I am just designing a system that uses that as a CPU and trying to give you some assistance.

If you run the program with the servo disconnected, does the behavior persist?

If there is no reboot without a servo connected and there is a reboot with a servo connected, then the power for the servo must be coming from the output of the WiFi Kit 32. If this is the case, then you should provide the +5V to the servo from the 6amp source rather than using the CPU to drive it.