6. Introduction to the ESP32

ESP32 dev kit power options

In this lesson, you will learn how to power your ESP32 dev kit.

You can watch the video, or if you are the “reading” type, you can read the text below.

Option 1: USB

The easiest way to power your ESP32 dev kit is to use the USB port. The dev kit includes a micro USB port through which you can both supply power to the board, and implement serial communication with the host computer for uploading a sketch.

The easiest way to power your ESP32 dev kit is via the USB port.

Just plug one end of the cable into your computer’s USB port or to a USB compatible power, the other end to the USB port of the ESP32 dev kit, and you’re good to go.

Option 2: Unregulated power to GND and 5V pins

The second option is to connect an external unregulated power supply to the 5V pin and ground pins. Anything between around 5 and 12 Volts should work.

But it is best to keep the input voltage to around 6 or 7 Volts to avoid losing too much power as heat on the voltage regulator.

You can connect external power via the 5V and GND pins. Beware of the voltage limits.

I did some experimentation using my bench power supply. I supplied voltage between 5V and 10V and observed the current draw. The ESP32 was running a sketch with an empty loop.

At 10V input voltage, the current draw was 0.099 A (or 99.9mA).

At 5V, the current draw was a little higher, at 0.128 A (or 128mA).

At 10V input voltage, the current draw was 9.99mA.

At 5V, the current draw was 12.8mA.

Option 3: Regulated power to GND and 3.3V pins

Another option that you have is to power your ESP32 is to use a 3.3V regulated power supply. For this, you will use the 3.3 Volt and GND pins.

You can connect a regulated 3.3V voltage supply to the 3.3V and GND pins.

The 3.3 volts pin is at the top left of the board right next to the antenna.

You have to be very careful when you do that. If you power your ESP32 this way, you’re bypassing the on-board voltage regulator that is on board the dev kit, and therefore your module has no protection against over-voltage.

Again: Be very careful to make sure that your input voltage on the 3.3V pin is regulated and safe.

Power: conclusion

To power your ESP32 dev kit, you have three options:

  1. Via the USB port.
  2. Using unregulated voltage between 5V and 12V, connected to the 5V and GND pins. This voltage is regulated on-board.
  3. Using regulated 3.3V voltage, connected to the 3.3V and GND pins. Be very careful with that: do not exceed the 3.3V limit, or your ESP32 module will be damaged.

Attention: be very, very careful to only use one of those options at the same time.

For example, do not power your ESP32 dev kit via the 5V pin using a 10V input while at the same time you have the module connected to your computer via USB. This will surely damage your module, and perhaps even your computer.

With this, you should have a good understanding of what the ESP32 is, and you must be eager to get hands-on with it. I totally understand :-). Let’s proceed with the next lesson, where I’ll show you how to set up the ESP32-Arduino Core on the Arduino IDE.

"Introduction to the ESP32" series

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  • At 10V input voltage, the current draw was 0.099 A (or 9.99mA). – 0.099A = 99mA
    At 5V, the current draw was a little higher, at 0.128 A (or 12.8mA). – 0.128A = 128mA

    • On the power supply side, the maximum Voltage that USB can provide is 5V, at 5A (see the latest USB Type-C rev2.0).

      On the ESP32, you can easily damage the board if you are not careful, i.e. by accidentally shorting pins etc.

      If you need to drive large loads, consider things like relays and transistors connected to an appropriate power supply.

      • Hi, Peter.

        Related with the USB option, let my put another question. What’s the limit, regarding amps?
        I have a few smartphone / tablet power supplys lying around, but I’m always concerned if it is too much.

        In a nutshell, via the USB:

        Max voltage?
        Max amps?
        Max power?

        Best regards, and sorry for my poor english.

        • Hi Tiago,

          A certified USB power supply/charger will always be 5V.

          The ESP32 will just draw the power that it needs.

          As long as the power supply can provide this power, the ESP32 will work.

          Again, as long as the USB power supply is certified (i.e. of decent quality), it will not damage any USB device you connect to it, including an ESP32 dev kit.

  • Using option 2, how can I connect AA battery to power ESP32 and operate WiFi and bluetooth modes normally? Which AA battery is to be used ?

      • In Option2, with 4AA cells, the current will not be enough as peak WiFi operation will require 300-400mA. How to ensure required current is provided ?

        • Try using a capacitor, 10uF or larger, that will be able to supply enough current at peak Wifi.

          Or, you can use a Lipo battery that should be able to cover peak current without a capacitor.

  • In option 3, how to provide regulated 3.3V voltage using AA batteries to ensure current requirements are met ? in series or parallel? how many AA ? What is the power supply circuit for this ?

  • Hello
    My program runs fine off first option (USB) but when I use the second option I am having problems. when I have 5V connected to 5V and GND; board starts up but when it gets to the part of my program where I am initializing my WIFI the board resets, resetting happens a few more times until it is finally to get through WIFI part. Any idea what’s going on?
    thanks

    • Hi MJ,

      can you please describe what kind of 5V power supply you are using? It is likely that when the Wifi kicks in, there is a voltage drop that causes the problem.

      Try increasing the voltage from 5V to 6V on the 5V pin to see if that improves reliability.

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