38. 1-Wire

38.1. 概述

本示例展示了通过1-Wire总线访问数字温度传感器DS18B20。

HPM 1-Wire特性如下：

• 1-Wire Master

• Reset and Rresence Pulses(RPP) 输出及1-Wire Slave检测

• 单字节或多字节读写

• DMA模式

• SRA模式

• 中断

38.2. 硬件设置

无

38.3. 背景

1-Wire(单总线) 是DALLAS公司推出的外围串行扩展总线技术总线，顾名思义，它是采用一根信号线进行通信，既传输时钟信号又传输数据，而且能够进行双向通信，具有节省I/O口线、资源结构简单、成本低廉、便于总线扩展和维护等诸多优点。常用到单总线的器件，一般是稳定传感器、EEPROM、唯一序列号芯片等，如DS18B20、DS2431等。

38.4. 运行现象

• 串口终端显示如下信息

  This is a onewire sample: DS18B20
  OWR Slave Detected!
  Family Code: 28
  Serial Num:67 e2 79 00 00 00
  CRC: 3a
  Thermometer resolution: 12 bit
  Current Temp: 26.94 degree centigrade
  Current Temp: 26.94 degree centigrade
  Current Temp: 26.87 degree centigrade
  Current Temp: 26.94 degree centigrade
  Current Temp: 26.87 degree centigrade
  Current Temp: 26.87 degree centigrade
  Current Temp: 26.94 degree centigrade
  Current Temp: 27.25 degree centigrade
  Current Temp: 27.69 degree centigrade
  Current Temp: 28.06 degree centigrade
  Current Temp: 28.31 degree centigrade
  Current Temp: 28.50 degree centigrade
  Current Temp: 28.62 degree centigrade
  Current Temp: 28.44 degree centigrade
  Current Temp: 28.31 degree centigrade
  Current Temp: 28.19 degree centigrade
  Current Temp: 28.06 degree centigrade