raspiSensors 2019.3.24.4

A series of convenience functions for Raspbery PI sensors

Raspberry Pi Sensors

This is a Python 3 package that enables Raspberry Pi to read various sensors .It has been tested on Python 3.5/Raspbian (stretch). Supported devices include:

• HCSR04 ultrasonic sensor
• PCA9685 Adafruit 16-channel 12 Bit PWM Driver
• BMP280 Barometer
• Triple Axis Magnetometer QMC5883L

REQUIREMENTS

1. adafruit-circuitpython-servokit

Installation

1. From source (incl. examples, fritzing and ebooks)

      git clone https://github.com/hanshof/rpiSensors.git
      cd rpiSensors
      python install setup.py

2. PIP

    pip install raspiSensors
    

HCSR04 ultrasonic sensor

This is the HC-SR04 ultrasonic distance sensor. This economical sensor provides 2cm to 400cm of non-contact measurement functionality with a ranging accuracy that can reach up to 3mm. Each HC-SR04 module includes an ultrasonic transmitter , a receiver and a control circuit.

There are only four pins that you need to worry about on the HC-SR04: VCC (Power), Trig (Trigger), Echo (Receive), and GND (Ground). You will find this sensor very easy to set up and use for your next range-finding project!

Example:

  from raspiSensors import hcsr04 as HCSR04
  ultrasonic = HCSR04(trigger_pin = 21, echo_pin = 20)
  print(ultrasonic.distance())

  returns distance in cm
  

PCA9685 Adafruit 16-channel 12 Bit PWM Driver

Using only two pins, control 16 free-running PWM outputs! You can even chain up 62 breakouts to control up to 992 PWM outputs (which we would really like to see since it would be glorious) It's an i2c-controlled PWM driver with a built in clock. That means that, unlike the TLC5940 family, you do not need to continuously send it signal tying up your microcontroller, its completely free running! It is 5V compliant, which means you can control it from a 3.3V microcontroller and still safely drive up to 6V outputs (this is good for when you want to control white or blue LEDs with 3.4+ forward voltages) 6 address select pins so you can wire up to 62 of these on a single i2c bus, a total of 992 outputs - that's a lot of servos or LEDs Adjustable frequency PWM up to about 1.6 KHz 12-bit resolution for each output - for servos, that means about 4us resolution at 60Hz update rate Configurable push-pull or open-drain output Output enable pin to quickly disable all the outputs

Example:

    from raspiSensors import pca9685 as PCA9685
    servos = PCA9685(channels=16)
    
    servos.kit.servo[0].angle = 90

BMP280 Barometer

This is a Barometer Pressure Sensor module It could measure the pressure and temperature. This program depend on BMP280.py writted by Adafruit.

 
 from raspiSensors import bmp280 as BMP280
 sensor = BMP280.BMP280()
 elev = 240 # altitude of your location in meters
 print('Temp = {0:0.1f} *C'.format(sensor.read_temperature()))
 print('Pressure = {0:0.1f} hPa'.format(sensor.read_pressure()/10**2))
 print('Sealevel Pressure = {0:0.1f} hPa'.format(sensor.read_sealevel_pressure(elev)/10**2)) # altitude of your location in meters

Triple Axis Magnetometer QMC5883L

Magnetometer QMC5883L is used for measuring the direction and magnitude of the Earth’s magnetic field. It is used for low cost compassing and magnetometry. It measures the Earth’s magnetic field value along the X, Y and Z axes from milli-gauss to 8 gauss. It can be used to find the direction of heading of the device. It uses I2C protocol for communication with microcontroller.

    from raspiSensors import qmc5883l as QMC5883L
    from time import sleep

    sensor = QMC5883L()
    sensor.set_declination(8.0)

    while True:

       # Read Accelerometer raw value

       m = sensor.get_magnet()
       heading = sensor.get_bearing()

       print("Heading Angle = %d°" % heading)
       print("Magnet = {}".format(sensor.get_magnet()))

       sleep(1)