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README.md

mruby-raspberry

mruby gem for accessing Raspberry IO.

##Intro mruby-raspberry is a wrapper around wiringpi library. At the moment, it support most of the original basic functionalities, excluding I2C, SPI, Shift, Software PWM, and Software Tone.

##Requirements and Building The wiringpi library v2 needs to be installed before using this mruby-gem. Additionally, packages i2c-tools and libi2c-dev must be installed.

Testing

To do a quick test, after installing WiringPi, proceed as follows:

$ git clone --depth 1 https://github.com/uniTN-Mechatronics/mruby-raspberry.git
$ cd mruby-raspberry
$ ./run_test.rb           # this also clones mruby master
$ sudo tmp/mruby/bin/mirb # sudo needed for accessing hw pins

Adding to your mruby

To use it within your custom mruby, just add conf.gem :github => 'UniTN-Mechatronics/mruby-raspberry', :branch => 'master' in your build_config.rb

##Usage The C functions of the original WiringPi library are grouped under the module Raspberry. Each of the categories in which the WiringPi functions are collected is implemented either as a submodule of Raspberry or as a class when it makes sense:

  • Raspberry::Core: module
  • Raspberry::Specifics: module
  • Raspberry::Timing: module
  • Raspberry::Serial: class

The Raspberry module only has one function, setup(), which maps the wiringPiSetup C call. Note: if you include Raspberry, the setup function is automatically called; otherwise, you explicitly need to call it for the rest to work.

The following is the list of the implemented functions/methods. For details, see the original WiringPi documentation.

Raspberry::Core

  • pin_mode(pin, mode), mode is one of the constants INPUT, OUTPUT, PWM_OUTPUT, or GPIO_CLOCK
  • pull_mode(pin, mode), mode is one of the constants PUD_OFF, PUD_DOWN or PUD_UP
  • digital_write(pin, level), level is one of the constants HIGH, LOW
  • pwm_write(pin, value)
  • digital_read(pin)
  • analog_write(pin, value)
  • analog_read(pin)

Raspberry::Specifics

  • write_byte(value), value is casted into a 8 bit int
  • pwd_set_mode(), mode is one of the constants PWM_MODE_BAL or PWM_MODE_MS
  • pwm_set_range(value)
  • pwm_set_clock(value)
  • board_rev(), returns either 1 or 2
  • wpi_pin(), converts WirnigPI pin number into GPIO pin number
  • phys_pin(), converts physical pin number into GPIO pin number

Raspberry::Timing

  • millis()
  • micro()
  • delay(value)
  • delay_micro(value)

Raspberry::Serial

  • Serial.valid_rate?(rate), returns true if rate is a standard valid baud rate
  • Serial.new(port, baud), creates and opens a serial port connection
  • Serial#close()
  • Serial#put_char(chr), only the first character of chr is used
  • Serial#puts(str)
  • Serial#data_avail()
  • Serial#get_char()
  • Serial#flush()
  • Serial#printf(fmt, ...)

Raspberry::I2C

This class supports TWI/I2C communication, or at least a subset of it. It has been tested against an Arduino Uno directly connected to a Raspberry Pi Rev.2, see here for details.

Requirement: Remember to sudo apt-get install i2c-tools libi2c-dev before building!

Supported methods:

  • I2C.new(id): creates a new instance over the given I2C device ID
  • I2C#write(arg): writes a String or an Array of Fixnums to the selected device ID. If arg is a single integer or char, writes it directly. If it is a string or an array of Fixnums, iterates over the elements with a delay between each write that can be set via I2C#delay=(v) (delay is in milliseconds, default to 5000 ms)
  • I2C#read(n=nil): reads value(s) from the selected device ID. If n=nil, it reads a single value (as Fixnum). If n > 0, it performs exactly n read operations waiting @delay every time, and returns an array of n Fixnums
  • I2C#read_chr: Reads a single value and converts it to a single character

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