rpi_i2c

Description:

rpi i2c

rpi_i2c.dart #

rpi_i2c is a Dart package for using I2C on the Raspberry Pi.
Overview #


The I2C library provides the API for accessing devices
using the I2C protocol


The RpiI2C library provides implementation of
the I2C protocol on the Raspberry Pi derived from the WiringPi library.


Setup #
Be sure to enable I2C on the Raspberry Pi using
sudo raspi-config
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RpiI2C uses a native library written in C.
For security reasons, authors cannot publish binary content
to pub.dartlang.org, so there are some extra
steps necessary to compile the native library on the RPi before this package
can be used. These two steps must be performed when you install and each time
you upgrade the rpi_i2c package.

Activate the rpi_i2c package using the
pub global command.

pub global activate rpi_i2c
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From your application directory (the application that references
the rpi_i2c package) run the following command to build the native library

pub global run rpi_i2c:build_native
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pub global activate
makes the Dart scripts in the rpi_i2c/bin directory runnable
from the command line.
pub global run
rpi_i2c:build_native runs the rpi_i2c/bin/build_native.dart
program which in turn calls the build_native script
to compile the native librpi_i2c_ext.so library for the rpi_i2c package.
Examples #



File
Description




example.dart
instantiating and accessing an I2C device


mpl3115a2.dart
Mpl3115a2 pressure sensor with altimetry


ttp229.dart
TTP229 I2C touchpad


tsl2561.dart
TSL2651 light sensor which is embedded in the Grove Light Sensor v1.1



Multiple devices can be connected to the I2C bus at the same time.
Connect the following pins on the Raspberry Pi
to pins on the Adafruit MPL3115A2
and pins on the TTP229 Touchpad
It is recommended to attach
two 4.7K pullup resistors,
one to the SDA line and a second to the SDL line,
althrough with some device boards already have pullup resistors on them.
If you have many I2C devices and/or a long I2C bus, you many need a different value
as per I2C pullup resistor recommendations.



Rpi Pin
MPL3115A2
TTP229
Pull-up Resistors




PIN #1 (3.3v)
3V
3V



PIN #3 (SDA1 / I2C)
SDA
SDA
4.7K resistor to 3.3V


PIN #5 (SDL1 / I2C)
SDL
SDL
4.7K resistor to 3.3V


PIN #6 (GND)
GND
GND




With thanks to Pierre Henelle for the RPi_MPL3115A2 library
for wiring and inspiration. In that library's readme, there's a good
picture of the RPi connected to the MPL3115A2.