ruby-i2c-devices
i2c-devices is a library for using I2C devices.
SYNOPSYS
Usage of I2CDevice class directly:
require "i2c"
require "i2c/driver/i2c-dev"
device = I2CDevice.new(address: 0x60, driver: I2CDevice::Driver::I2CDev.new("/dev/i2c-1"))
# like i2c-tools's i2cget command
length = 3
device.i2cget(0x01, length)
# like i2c-tools's i2cset command
device.i2cset(0x01, 0x11, 0x12 ... )
or pre-defiend device driver class:
require "i2c/device/acm1602ni"
lcd = I2CDevice::ACM1602NI.new
lcd.put_line(0, "0123456789ABCDEF")
with driver class
require "i2c/device/mpl115a2"
require "i2c/driver/i2c-dev"
mpl = I2CDevice::MPL115A2.new(driver: I2CDevice::Driver::I2CDev.new("/dev/i2c-0"))
p mpl.calculate_hPa
or GPIO backend driver (this is very slow)
require "i2c/device/mpl115a2"
require "i2c/driver/gpio"
mpl = I2CDevice::MPL115A2.new(driver: I2CDevice::Driver::GPIO.new(
sda: 23, # pin 16 in raspberry pi
scl: 24, # pin 18 in raspberry pi
))
p mpl.calculate_hPa
Class
I2CDevice
Generic class for manipulating I2C device.
I2CDevice.new(address: address, driver: driver)
- address : Integer : 7-bit slave address without r/w bit. MSB is always 0.
- driver : I2CDevice::Driver : backend driver class. (default: I2CDevice::Driver::I2CDev)
I2CDevice#i2cset(*data) #=> Integer
Write data
to slave.
Returns Integer
which is bytes length wrote.
I2CDevice#i2cget(param, length=1) #=> String
This method read data from slave with following process:
- Write
param
to slave - re-start
- Read data until NACK or
length
Returns String
.
I2CDevice::Driver::I2CDev
This depends on /dev/i2c-* (i2c-dev) feature on Linux. You may load i2c-dev kernel module.
I2CDevice::Driver::I2CDev.new(path)
- path : String : Path to /dev/i2c-*
I2CDevice::Driver::GPIO
This depends on /sys/class/gpio feature on Linux and implements by bit-banging.
I2CDevice::Driver::I2CDev.new(sda: sda, scl: scl, speed: speed)
- sda : Integer : Pin number of SDA.
- scl : Integer : Pin number of SCL.
- speed : Integer : I2C clock speed in kHz. (default: 1)
Pin number of sda
and scl
is not real pin number but logical pin number.
Eg. In Raspberry Pi, specifing sda: 23, scl: 24
means using 16 and 18 pin.
You can specify 100 kHz or 400 kHz (or more) to speed
but speed is rate-limited by host CPU speed.
Typically, this module fall short of requirements of I2C spec (in Raspberry Pi, clock speed is about 1.3kHz).
But most slave devices support DC~100kHz clock speed.
REQUIREMENTS
Currently this library depends on Linux's i2c-dev or sysfs with GPIO feature.
- I2CDevice::Driver::I2CDev /dev/i2c-0 (i2c-dev), default
- I2CDevice::Driver::GPIO /sys/class/gpio (GPIO)
TODO
- More supported devices