Published February 12, 2019 © CC BY-SA

DIY ESP8266-Based Badge

This badge is a DIY dev board for MicroPython. Based on ESP8266, it has a lot of features which are possible to learn and have fun with!

BeginnerFull instructions provided3 hours1,636

The Badge of IoT

BadgeLove!

Things used in this project

Hardware components

DHT11 Temperature & Humidity Sensor (4 pins)

Adafruit OLED

Buzzer

SparkFun Mini Photocell

Adafruit Flora RGB Neopixel LEDs- Pack of 4

NXP PCF8574AP

SparkFun Pushbutton switch 12mm

NodeMCU ESP8266 Breakout Board

LED (generic)

Resistor 10k ohm

Resistor 4.75k ohm

Resistor 1k ohm

Resistor 330 ohm

General Purpose Transistor NPN

SparkFun Snappable Protoboard

Hand tools and fabrication machines

Soldering iron (generic)

SparkFun Flush Cutters - Xcelite

SparkFun Solder Leaded - 100-gram Spool

Story

This badge was developed due to my need for a board to learn about MicroPython with an ESP8266. Although it's easy to test using a breadboard, I needed a more robust board that I could bring with me outside the lab and for a demonstration at a event.

I didn't have time to make a layout, send to manufacture, and assemble the board. And for now, I only need one board.

So, I decided to make a DIY dev board, using the components that I have in my lab. As I had to present a talk on MicroPython at Campus Party Brasil, I chose to build it in badge format so that I could easily show it to the public.

Below, you find all the details of badge hardware.

Schematic

To explore the features of MicroPython, I decided to put a variety of modules. The schematic was drawn in EasyEDA:

Board Schematic

Board Features

NodeMCU
DHT11
OLED display
Buzzer
LDR
NeoPixel with expander connector
PCF8574AP (4 Entradas e 4 Saídas)
I2C expander
SPI expander

Assembly

For assembly the board the soldering was done on prototyping perfboards. Following the schematic, I fixed the components and made the tracks with solder wire.

1 / 8 • Board Soldering

In some cases jumpers were required. They were made with terminals of the components used.

1 / 6 • Board Soldering

Board Testing

The video shows a test of all peripherals with MicroPython:

Code

Demo - MicroPython test

from machine import Pin,I2C,ADC
import ssd1306
from neopixel import NeoPixel
from dht import DHT11
from time import sleep


i2c = I2C(scl=Pin(5), sda=Pin(4), freq=100000)  #Init i2c
i2c.scan()


lcd=ssd1306.SSD1306_I2C(128,64,i2c)             #create LCD object,Specify col and row
d = DHT11(Pin(2))
adc0=ADC(0)                                     #create ADC object on ADC pin
pin = Pin(0, Pin.OUT)                           # set GPIO0 to output to drive NeoPixels
np = NeoPixel(pin, 6)                           # create NeoPixel driver on GPIO0 for 8 pixels
buzzer = Pin(15, Pin.OUT)

i2c.writeto(0x38, bytes(0xFF))                  #Start PCF

buzzer.value(1)
sleep(0.2)
buzzer.value(0)
sleep(0.2)

np.write()

lcd.text("Hello",0,0)                           
lcd.text("TESTE",0,16)                       
lcd.text("MICROPYTHON",0,32)     
lcd.text("BOARD",0,48) 
lcd.show()                                      #display

sleep(1.0)

x = 0
y = 0
z = 0
tempo = 4

while True:
  sleep(0.01)
  
  tempo+=1
  if tempo == 5:
    tempo = 0
    d.measure()
    temp = '{:.1f}'.format(d.temperature())
    hmdty = '{:.1f}'.format(d.humidity() )
    
    lcd.fill(0) 
    lcd.text('T:', 0, 0)
    lcd.text(temp ,20,0)                         #set "DFRobot" at (0,0)
    lcd.text('H:', 0, 20)
    lcd.text(hmdty ,20,20)                         #set "DFRobot" at (0,0)
    #lcd.show()                                      #display
    
    #print(temp)
    #print(hmdty)

    np[x] = (0, 0, 0)       # set the first pixel to white
    np.write()              # write data to all pixels
    x+=1
    if x == 6: 
      x=0
      
    np[x] = (0, 0, 255)     # set the first pixel to white
    np.write()              # write data to all pixels

    buf = bytearray(1)
    buf[0] = 255
    i2c.writeto(0x38,buf)
    
    buf[0] = 0xff &~(1<<0|1<<1|1<<2|1<<3)
    i2c.writeto(0x38,buf)
    
    buf[0] = 0xF0|(1<<y)
    i2c.writeto(0x38,buf)
    y+=1
    if y==4:
      y = 0
  
  buf = i2c.readfrom(0x38,1) 
  z = buf[0]
  z=z>>4
  #print(z)
  
  if z == 7:
    lcd.text('Tecla: 1', 0, 40)
    buzzer.value(1)
    sleep(0.2)
    buzzer.value(0)
    sleep(0.2)
  elif z == 11:
    lcd.text('Tecla: 2', 0, 40)
    buzzer.value(1)
    sleep(0.2)
    buzzer.value(0)
    sleep(0.2)
  elif z == 13:
    lcd.text('Tecla: 3', 0, 40)
    buzzer.value(1)
    sleep(0.2)
    buzzer.value(0)
    sleep(0.2)
  elif z == 14:
    lcd.text('Tecla: 4', 0, 40)
    buzzer.value(1)
    sleep(0.2)
    buzzer.value(0)
    sleep(0.2)
  else:
    lcd.text('Tecla: -', 0, 40)
  
  lcd.show()