DIY ESP-01 Motherboard

NodeMCU and other ESP8266 modules are starting to become very popular because they offer an embedded development platform with a CPU+RAM+Storage+WiFi all in one for (considerably) less than the price of an Arduino. There are a number of breadboard-friendly modules with all pins exposed (and more coming soon.)

However, this post is about the breadboard-unfriendly ESP-01 module. It only has two GPIO pins (four if you include the TX & RX pins), but it's smaller and most importantly, cheaper.

US vendors tend to charge around $7, but if you don't mind importing, they can be had for $3.50 or less.

The biggest problem with the ESP-01 is that it's annoying to wire up and program, so that's what we're solving today.

Parts

• ESP-01 module: The reason were going through all this trouble. $3.50 @ Electrodragon

• USB-Serial TTL programmer: I'm using an Adafruit FTDI Friend, although I'm hesitant to recommend FTDI products after they shipped mallware with their Windows drivers... $14.75 @ Adafruit.

  Update: I've confirmed that a CP2102 USB-TLL UART also works well on OS X: $2.20 @ Electrodragon. You can either use the included cable, or switch the pin headers on the motherboard to female for a direct connection. (All relevant pins are in the same position.)

• 3.3v Voltage Regulator: Needs to be a slightly beefy one because the ESP8266EX chips can reportedly draw as much as 350-400mA. I'm using a LM2937ET-3.3/NOPB from TI. $1.61 @ Texas Instruments (Or request a free sample)
• 10 μF Capacitor: For the 3.3v side of the voltage regulator. $0.02 each @ Tayda Electronics or $3.30 for a 120-piece kit @ Electrodragon
• 0.1 μF Capacitor: (100nf) For the vin/5v side of the voltage regulator. $0.02 each @ Tayda Electronics (Or use the 0.2uf Capacitor from the aforementioned Electrodragon kit
• Two Buttons: SPST (Single Pole, Single Throw) momentary on switches. I'm using Omron B3F buttons. $0.04 each @ Tayda Electronics or $1.20 for 50 @ Electrodragon
• 10k Ω Resistor: Pull-up for the Reset button. (Note: depending on your usage, your may also want a second one for the Program button on GPIO 0.) $0.10 for 10 @ Tayda Electronics or $0.90 for 100 @ Electrodragon or $3 for a 600-piece kit @ Electrodragon
• 1k Ω Resistor: Pull-up for the CH_PD pin that enables the ESP-01 module. $0.10 for 10 @ Tayda Electronics or $0.90 for 100 @ Electrodragon or the aforementioned $3 600-piece kit @ Electrodragon
• 2x4 Female Pin Headers: For connecting the ESP-01 module. (I'm not even sure where to buy these, I think mine was a free sample from Samtec that was leftover from a different project. Nobody will look down on you if you just break off two 1x4 pieces of single-row pin headers and solder them side-by-side ;)
• Male and Female Breakaway Pin Headers: For connecting USB-Serial TTL programmer and connecting to the GPIO pins. $0.90 (male) & $1.70 (female) @ Electrodragon + $1.40 (male, right-angle - optional) @ Electrodragon
• Stripboard: The "board" part of our motherboard. $0.66 @ Tayda Electronics
• Misc Wire: A few short pieces of wire, probably less than 2 inches total. $0.10 per foot @ Tayda Electronics or $1.60 for 10 meters @ Electrodragon
• Brass Spacers: Optional but keeps the board from potentially shorting out on your desk/whatever. $0.90 for 10 @ Electrodragon

Total cost: ~$12 + shipping to go with the cheapest options. Be aware that Tayda Electronics has a minimum order of $5, so with that and shipping you'll probably have to spend $20-25 to get everything.

Tools

• Soldering Iron & Solder: I recently upgraded to a Weller WESD51 and I am loving it.
• Flush Cutters: To cut the leads off after soldering each part in. These are also handy for "breakaway" female pin headers.
• Wire Strippers: For cutting and stripping the few bits of wire we need.
• X-Acto Knife: Necessary for cutting the stripboard track between the two rows of pins on the ESP-01 module, and a fallback option for the other cuts.
• Drill w/ 4mm drill bit: Makes all of the other stripboard cuts much easier. Just position the drill in the center of an unused pin hole and spin it for a few moments to strip away the copper.

Building

(Fritzing .fzz file, uses Yan Donelly's ESP-01 Fritzing part)

Connect everything as shown in the diagram. Be sure to cut the stripboard tracks between the two rows of pins where the ESP-01 connects. (And the other locations - the CH_PD track and a few on either side of the power tracks - but you can see each of those cuts in the graphic.)

I changed the spacing a bit when I assembled mine to give my fingers more room to connect and disconnect things from the pin headers.

Programing

There are a few ways to program the ESP-8266, but my favorite is to use the Arduino IDE with the ESP8266 board from esp8266.com. Adafruit has a nice guide for installing it.

When uploading your sketch, you have to be a little carefule about the order and timing of the button presses:

1. Click upload in the Arduino IDE
2. Quickly press and hold the RESET button (the one farther from the ESP-01)
3. Quickly press and hold the PROGRAM button
4. Watch the status line in the Arduino IDE. When it changes from "Compiling..." to "Uploading..." release the RESET button
5. After you see it starting to print the upload status in red text, release the PROGRAM button.

Here's an example sketch to use PROGRAM button on GPIO 0 as a regular input:

const int buttonPin = 0;

void setup() {
 Serial.begin(9600);
 // Normally the button will take the pin from "floating" (not connected to anything) to grounded
 // This enables the internal pullup resistor so that the default state is high rather than floating.
 pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
  Serial.print("Button is ");
  int status = digitalRead(buttonPin);
  // because of the pullup resistor, the pin state is reversed: button pressed = LOW, button released = HIGH
  if (status == LOW) {
    Serial.println("pressed");
  } else {
    Serial.println("released");
  }
  delay(500);
}

Happy hacking! Discuss on esp8266.com.