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https://github.com/nickoala/sensor
Raspberry Pi Sensors
https://github.com/nickoala/sensor
bmp180 ds18b20 htu21d mcp3004 mcp3008 python raspberry-pi sensor sht20
Last synced: about 1 month ago
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Raspberry Pi Sensors
- Host: GitHub
- URL: https://github.com/nickoala/sensor
- Owner: nickoala
- Created: 2015-09-08T06:44:34.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2021-03-06T11:24:28.000Z (almost 4 years ago)
- Last Synced: 2024-11-07T23:45:20.276Z (about 1 month ago)
- Topics: bmp180, ds18b20, htu21d, mcp3004, mcp3008, python, raspberry-pi, sensor, sht20
- Language: Python
- Size: 55.7 KB
- Stars: 79
- Watchers: 11
- Forks: 20
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
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README
# Raspberry Pi Sensors
This is a **Python 3** package that enables **Raspberry Pi** to read various
sensors.
Supported devices include:
- **DS18B20** temperature sensor
- **BMP180** pressure and temperature sensor
- **HTU21D** humidity and temperature sensor
- **SHT20** humidity and temperature sensor
- **MCP3004** A/D Converter (**MCP3008** also compatible)
The chief motivation for this package is educational. I am teaching a Raspberry
Pi course, and find it very troublesome for students having to download a
separate library every time they use another sensor. With this package, download
once and they are set (for my course, anyway). I hope you find it useful, too.
## Installation
It is best to update Linux first.
`sudo apt-get update`
`sudo apt-get dist-upgrade`
Install this package:
`sudo pip3 install sensor`
But the `sensor` package would not work by itself. Communicating with sensors
often requires some sort of serial protocol, such as **1-wire**, **I2C**, or
**SPI**. You have to know which sensor speaks which, and set up Raspberry Pi to
do so.
## Enable 1-Wire, I2C, or SPI
`sudo raspi-config`, enter **Interfacing Options**, enable the protocols you
need.
## Know your sensor's address
Unlike many libraries out there, this library knows **no default bus number**
and **no default device address**. I want learners to be explicitly aware of
those numbers, even if they are fixed.
For example:
- **I2C** bus is numbered **1**
- **SPI** bus is numbered **0**
To find out individual sensor's address:
- For 1-wire sensors, go to `/sys/bus/w1/devices/`
- For I2C sensors, use `i2cdetect -y 1`
- For SPI sensors, you should know which CS pin you use
## My sensors don't give simple numbers
Unlike many libraries out there, this library does not return a simple Celcius
degree when reading temperatures, does not return a simple hPa value when
reading pressure, does not return a simple RH% when reading humidity, etc.
Instead, I return a **namedtuple** representing the quantity, which offers two
benefits:
- No more conversion needed. Suppose you get a *Temperature* called `t`, you may
access the Celcius degree by `t.C` as easily as you do Fahrenheit by `t.F`.
- Namedtuples may have methods. For example, a *Pressure* has a method called
`altitude()`, which tells you how high you are above mean sea level.
## DS18B20
- Temperature, 1-wire
- To find out the sensor's address:
```
$ cd /sys/bus/w1/devices/
$ ls
28-XXXXXXXXXXXX w1_bus_master1
```
Read the sensor as follows:
```python
from sensor import DS18B20
ds = DS18B20('28-XXXXXXXXXXXX')
t = ds.temperature() # read temperature
print(t) # this is a namedtuple
print(t.C) # Celcius
print(t.F) # Fahrenheit
print(t.K) # Kelvin
```
## BMP180
- Pressure + Temperature, I2C
- Use `i2cdetect -y 1` to check address. It is probably `0x77`.
```python
from sensor import BMP180
# I2C bus=1, Address=0x77
bmp = BMP180(1, 0x77)
p = bmp.pressure() # read pressure
print(p) # namedtuple
print(p.hPa) # hPa value
t = bmp.temperature() # read temperature
print(t) # namedtuple
print(t.C) # Celcius degree
p, t = bmp.all() # read both at once
print(p) # Pressure namedtuple
print(t) # Temperature namedtuple
# Look up mean sea level pressure from local observatory.
# 1009.1 hPa is only for example.
a = p.altitude(msl=1009.1)
print(a) # Altitude
print(a.m) # in metre
print(a.ft) # in feet
```
## HTU21D
- Humidity + Temperature, I2C
- Use `i2cdetect -y 1` to check address. It is probably `0x40`.
```python
from sensor import HTU21D
# I2C bus=1, Address=0x40
htu = HTU21D(1, 0x40)
h = htu.humidity() # read humidity
print(h) # namedtuple
print(h.RH) # relative humidity
t = htu.temperature() # read temperature
print(t) # namedtuple
print(t.F) # Fahrenheit
h, t = htu.all() # read both at once
```
## SHT20
- Humidity + Temperature, I2C
- Use `i2cdetect -y 1` to check address. It is probably `0x40`.
```python
from sensor import SHT20
# I2C bus=1, Address=0x40
sht = SHT20(1, 0x40)
h = sht.humidity() # read humidity
print(h) # namedtuple
print(h.RH) # relative humidity
t = sht.temperature() # read temperature
print(t) # namedtuple
print(t.C) # Celsius
h, t = sht.all() # read both at once
```
## MCP3004
- Analog sensors (e.g. photoresistor) cannot interface with Raspberry Pi
directly. They have to go through an A/D converter.
```python
from sensor import MCP3004
# SPI bus=0, CS=0, V_ref=3.3V
mcp = MCP3004(bus=0, addr=0, vref=3.3)
mcp.voltage(0) # read voltage on channel 0
```