ESP32 and DS18B20 sensor and Micropython example

In this example we look at a DS18b20 example in Micropython for an ESP32. Once again we use uPyCraft and again we use Wemos shields.

Lets remind ourselves about the DS18B20

The DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20 communicates over a 1-Wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor. In addition, the DS18B20 can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply.

Each DS18B20 has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same 1-Wire bus. Thus, it is simple to use one microprocessor to control many DS18B20s distributed over a large area. Applications that can benefit from this feature include HVAC environmental controls, temperature monitoring systems inside buildings, equipment, or machinery, and process monitoring and control systems

Requirements

Lets take a look a the shields and boards that are required for this example

Image	Summary
	MH-ET LIVE ESP32 MINI KIT WiFi+Bluetooth Internet of Things development board based ESP8266 Fully functional D1 MINI Upgraded
	This is not an official Wemos shield – this uses a DS18B20 and is connected to D2. This does mean that you can use another I2C device
	This is simply a base, you plug the Wemos Mini into one side and you can plug a shield or shields into the other side

Parts List

I connect the MH-ET LIVE ESP32 MINI KIT to the dual base and then put the DS18B20 shield along side this.

Code

Create a new file called dsESP32.py and import it into uPyCraft

[codesyntax lang=”python”]

from machine import Pin
import onewire
import ds18x20
import time

ow = onewire.OneWire(Pin(21))   #Init wire
ow.scan()
ds=ds18x20.DS18X20(ow)          #create ds18x20 object
while True:
  roms=ds.scan()                #scan ds18x20
  ds.convert_temp()             #convert temperature
  for rom in roms:
    print(ds.read_temp(rom))    #display 
  time.sleep(1)

[/codesyntax]

Output

You should see something like this

Ready to download this file,please wait!
…
download ok
exec(open(‘dsESP32.py').read(),globals())
85.0
27.125
27.125
27.0625
27.0625
27.0625
27.0625
27.0625
27.0625
27.0625
27.0625
27.0
27.0
27.0
26.9375
26.9375
26.9375

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