ds18x20 — ds18b20 Temperature sensor driver

One wire bus is a serial bus that uses only one wire for communication (except the wires used for grounding and power supply). The DS18B20 temperature sensor is a very popular single-wire device with the characteristics of conpact, low hardware overhead, strong anti-interference ability, and high accuracy.

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• Unique onewire (single bus) interface mode, DS18B20 only needs one port line to realize bidirectional communication between microprocessor and DS18B20 when connected with microprocessor.
• Temperature range －55℃～+125℃，
• Support multi-point networking function, multiple DS18B20s can be connected in parallel on the only three wires, and only a maximum of 8 can be connected in parallel to achieve multi-point temperature measurement. If the number is too large, the power supply voltage will be too low, resulting in stable signal transmission.
• Power Supply: 3.0~5.5V/DC

If you use a single ds18b20 device, in order to ensure stable data transmission, the OUT pin of the signal needs to be connected to a 4.7K pull-up resistor.

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DS18X20 class

class ds18x20.DS18X20(onewire)

Create DS18X20 class。

• onewire - one wire object sample

DS18X20.scan()

Scan the ds18b20 device on the single bus and return a list of device addresses.

DS18X20.convert_temp()

Obtain temperature sampling for convert temperature unit conversion.

DS18X20.read_temp(rom)

Returns the temperature value of the device. NOte that after convert_temp() converts the temperature, you need to wait at least 750 ms before reading the temperature value.

• rom - device address

Example-ds18b20

from machine import Pin
import onewire 
import time, ds18x20
# 创建one wire总线,引脚为P0
ow = onewire.OneWire(Pin(Pin.P0)) 
# 实例DS18X20类
ds = ds18x20.DS18X20(ow)
# 扫描总线上的DS18B20，获取设备列表
roms = ds.scan()  

while True:
    # 转换温度值,每次获取温度前必须调用convert_temp，否则温度数据不会更新
    ds.convert_temp()
    # convert_temp后至少等待750ms
    time.sleep_ms(750)
    # 返回总线的上ds18b20设备的温度值
    for rom in roms:
        print('Device %s temperature is %d'%(bytes(rom),ds.read_temp(rom)))