ESP01 Tester

The ESP-01 is a popular, very small and versatile microprocessor module with Wi-Fi. It is based on the ESP8266 chip, designed for adding wireless internet connectivity to your microcontroller projects. While compact and easy to integrate, it only exposes 2 GPIO pins for other peripherals.

I designed an easy to use test circuit that you can use to tryout any circuit based on this microprocessor before making your final design. You will not need a breadboard with many entangled wires, just plug in your ESP-01 and start programming and testing!

I used this test circuit to design the final hardware and software for my ESP01 Pluvio! Rain Gauge With Tipping Bucket.

See here: https://www.instructables.com/Pluvio-Rain-Gauge-With-Tipping-Bucket/

3x resistor 10k ohm

5x resistor 330 ohm

2x resistor 1k ohm

1x resistor 2k2 ohm

1x resistor 220 ohm

2x capacitor 100uF

1 led 5 mm. blue

1 led 5 mm. red

1 led 5 mm. orange

2x tactile pushbutton NO 2.54 mm.

PCB 27x19 holes with copper islands 2.54 mm. (80x50 mm.)

ESP01 microcontroller including socket

1 USB-C to TTL ch340e Serial module

LF33CV voltage regulator

1 40 pins header female

1 optocoupler 2N37 including socket

1 miniature flip switch ON-OFF

Mount all components on the PCB as shown in the drawings of the circuit diagram and the setup.

Use the 40 pins header female to make the various connection blocks. A few connections at the back must be made with insulated wiring.

First connect a 5VDC power supply on the large connection block on the left.

The first three connectors are GND, connectors 6,7 and 8 are for the 5VDC connection.

If you need 3.3VDC power for some external stuff you can use the last three connectors.

Programming the ESP01 using a USB-C to TTL ch340e Serial module:

Connect the USB-C to TTL ch340e Serial module as shown and connect your computer USB.

Note: This module is only connected to the Rx, Tx and GND connections of the USB of the connected computer, the power supply through this USB connection (coming from the computer) is disregared because it cannot deliver enough current.

Switch the flipswitch to the left to put the tester in program mode.

Press the reset button.

Upload the program sketch you want to use using the Arduino IDE program.

How to use the Arduino IDE program with the ESP01 see here:

https://wolles-elektronikkiste.de/en/esp8266-esp-01-module

Programming the ESP01 using an Arduino UNO R3:

Connect the Rx from the tester to the Rx from the Arduino.

Connect the Tx from the tester to the Tx from the Arduino.

This seems unusual, but you are only using the USB connection of the Arduino without the Arduino microcontroller itself.

Connect the GND from the Arduino to the GND from the tester.

Connect the Arduino UNO to your computer via USB.

To avoid interference with the USB conenction you can load an empty program into the Arduino or connect the RESET pin to GND.

For details how to program the ESP01 this way, see here:

https://github.com/RamNishanth/esp01

Switch the flipswitch to the right to put the tester in run mode.

Press the reset button to start.

GPIO2 can be used as INPUT. The status is shown with the blue led.

To activate the input you can use the input switch, which sets the input LOW via a 330 Ohm resistor.

Or you can use a remote switch for the same purpose via the black connector and GND.

It is also possible to use a separate input voltage between 3,3 and 5V to activate this input via its black connector. This voltage activates the GPIO2 input via a safe optocoupler. The red led shows the presence of this voltage.

GPIO2 can also be used as OUTPUT. The status is shown with the blue led.

This output is protected with a 330 Ohm resistor when the INPUT switch is acidentally activated.

GPIO0 is used as an OUTPUT. The status is shown with the orange led.

The output voltage (3,3VDC) can also be used to activate an external component via its black connector, through a safe 330 Ohm resistor.