Streaming Data from ESP32 using MicroPython and MQTT

Resources

• MicroPython and ESP32
• MicroPython
• MicroPython libraries
• MicroPython PiP Package Index
• ESP8266 Documentation (ESP32 not documeneted yet)
• ESP32 Firmware
• Adafruit MicroPython Resources

uMqtt PiP Packages

• umqtt.simple
• umqtt.robust

Other

• MicroPython BME280 Sensor Driver
• NTP Library
• Hackster MicroPython Mqtt Project
• Espressif esptool
• Mosquitto Broker
• PuTTY
• Serial Support on the Windows Subsystem for Linux

ESP32 MicroPython Firmware Flashing Process

See Adafruit MicroPython Flasing How-to Tutorial

Overview of ESP32 flashing process

1. Install esptool
2. Erase Flash
3. Deploy MicroPython Firmware

Install esptool.py firmware flash tool

On Windows

pip install esptool

On Mac and Linux

sudo pip install esptool

Erasing ESP32 flash

esptool.py --port /dev/ttyUSB0 erase_flash

Flashing ESP32 MicroPython firmware

Download ESP32 Firmware and deploy to ESP32.

esptool.py --chip esp32 --port /dev/ttyUSB0 write_flash 0x0000 firmware.bin

Installing Required MicroPython PIP Packages

Install the following uPip packages. You need to estabish a network connection on the ESP32 board then upip.install the umqtt packages.

import network
import upip

sta_if = network.WLAN(network.STA_IF)
sta_if.active(True)
sta_if.connect("Wifi SSID", "Wifi password")

upip.install('micropython-umqtt.simple')
upip.install('micropython-umqtt.robust')

MicroPython and Publish over MQTT

Deploy the boot.py and main.py files using the Adafruit ampy package.

See Adafruit MicroPython Tool (ampy) for information on copying files to the ESP32.

pip install adafruit-ampy

ampy --port /dev/ttyUSB0 put boot.py
ampy --port /dev/ttyUSB0 put main.py

# boot.py

import network
sta_if = network.WLAN(network.STA_IF)
sta_if.active(True)
sta_if.connect("Wifi SSID", "Wifi password")

# main.py

from umqtt.robust import MQTTClient
import machine
import utime as time
import gc
import bme280


# Wifi connect established in the boot.py file. Uncomment if needed
# import network
# sta_if = network.WLAN(network.STA_IF)
# sta_if.active(True)
# sta_if.connect("NCW", "malolos5459")

client = MQTTClient("esp32-01", "192.168.1.122")
pin5 = machine.Pin(5, machine.Pin.OUT)

i2c = machine.I2C(scl=machine.Pin(22), sda=machine.Pin(21))
bme = bme280.BME280(i2c=i2c)

def checkwifi():
    while not sta_if.isconnected():
        time.sleep_ms(500)
        print(".")
        sta_if.connect()

def publish():
    count = 1
    while True:
        pin5.value(0)
        checkwifi()
        v = bme.values
        msg = b'{"MsgId":%u,"Mem":%u,"Celsius":%s,"Pressure":%s,"Humidity":%s}' % (count, gc.mem_free(), v[0][:-1], v[1][:-3], v[2][:-1])
        client.publish(b"home/weather", msg)
        pin5.value(1)
        count = count + 1
        time.sleep(20)

client.reconnect()

publish()

Connecting to ESP32 with Putty

Install Putty for your platform. Connect at 115200 baud rate

See Adafruit Serial REPL Tutorial.