【使用笔记】树莓派基于Python操作IIC接口的红外测温传感器

最近在使用红外测温传感器，IIC通信，在单片机上已能读取数据，但是想把数据读取到电脑上用python做一些处理，想到树莓派自带IIC接口，于是尝试直接将红外传感器接到树莓派的IIC管脚。

1. 启用树莓派I2C功能：
   参考瑞士军刀扩展板的教程“DS1307 RTC 时钟模块”，开启树莓派的IIC功能，教程链接：
   http://shumeipai.nxez.com/2016/05/30/saks-diy-tutorials-ds1307-rtc-clock-module.html
   需要注意的是树莓派默认只能使用I2C1，I2C0是不能使用的。即要连接SDA.1和SCL.1
   
   这一步的主要工作是打开树莓派的I2C接口功能，并下载安装i2c-tool和python-smbus模块：
   sudo apt-get install i2c-tools python-smbus
   然后用命令查询是否检测到IC设备：
   sudo i2cdetect -y 1
   pi@raspberrypi:~ $ sudo i2cdetect -y 1
   0 1 2 3 4 5 6 7 8 9 a b c d e f
   00: – -- – -- – -- – -- – -- – -- –
   10: 10 – -- – -- – -- – -- – -- – -- – -- –
   20: – -- – -- – -- – -- – -- – -- – -- – --
   30: – -- – -- – -- – -- – -- – -- – -- – --
   40: – -- – -- – -- – -- – -- – -- – -- – --
   50: – -- – -- – -- – -- – -- – -- – -- – --
   60: – -- – -- – -- – -- – -- – -- – -- – --
   70: – -- – -- – -- – --

也可以用如下命令读取I2C设备的信息：
i2cdump -y 1 0x10 #0x10为I2C设备号
pi@raspberrypi:~ $ sudo i2cdump -y 1 0x10
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: ed 13 00 b1 17 00 00 cf f3 9f f5 b7 df 14 fd af ??.??..???
10: ba ec c7 00 00 00 00 00 00 00 00 00 00 00 00 00 ???..
20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 …
30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 …
40: ec 13 00 b0 17 00 00 cf f3 9f f5 b7 df 14 fd af ??.??..???
50: ba ec c7 00 00 00 00 00 00 00 00 00 00 00 00 00 ???..
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 …
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 …
80: ec 13 00 b0 17 00 00 cf f3 9f f5 b7 df 14 fd af ??.??..???
90: ba ec c7 00 00 00 00 00 00 00 00 00 00 00 00 00 ???..
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 …
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 …
c0: ed 13 00 bf 17 00 00 cf f3 9f f5 b7 df 14 fd af ??.??..???
d0: ba ec c7 00 00 00 00 00 00 00 00 00 00 00 00 00 ???..
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 …
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 …

2. 用python操作I2C设备
   python操作I2C的模块为smbus，库说明的链接如下：
   https://pypi.org/project/smbus2/0.1.2/
   常用的几个函数为：
   read_byte_data
   write_byte_data
   read_word_data
   write_word_data
   read_i2c_block_data
   write_i2c_block_data

具体读取I2C数据步骤：
（1）建立总线：
pi@raspberrypi:~ $ python3
Python 3.7.3 (default, Apr 3 2019, 05:39:12)
[GCC 8.2.0] on linux
Type “help”, “copyright”, “credits” or “license” for more information.

import smbus
i2c_bus = smbus.SMBus(1)
slave_addr = 0x10

（2）读取字节数据（偏移地址为0x80）：

i2c_bus.read_byte_data(slave_addr, 0x80)
15

（3）连续读取多个字节数据（起始偏移地址为0x80，读取8个字节）：

i2c_bus.read_i2c_block_data(slave_addr, 0x80, 8)
[17, 20, 0, 189, 23, 0, 0, 207]