Presentation

Discovered Omega2+, OpenWrt with 128MB for 10€ , I try it with ruby Lang.

The concurrents seems to be :

• Linkit smart : very near Onion product ( 12$ ), with Atmel chip for Arduino-compatibility
• Olimex RT5350 : 32MB RAM, with 5 Ethernets ports ( 15$ € )
• Arduino yun : more expensive ( 50$ ) 1 Ethernet, 64MB RAM
• RAK633 : 64MB RAM, 5 Ethernets ports, MT7628 , 10$ (? aliexpress)
• Banana PI RT1 : 5 Ethernets ports,512MB RAM, more more expensive (70$ ?)

Developer Plan

Previsions :

• V1 : develop this material without C librairie : use sysfs and some Onion exec (fast-gpio ...)
• V2 : link to onionlib shared library via FFI, provide same API as V1, but faster
• V3 : make a onion-mruby executable with all V2 io included :-)

Currently: V1 done, V2 is started (OLED)

TODO on V1 :

• develop a gpio library for digital input/output access
• develop a pwm library using fast-gpio
• OLED access ion I2C: seem ok with SSD1308 based Oled (text write, reset...)
• OLED create SSD130x file format from ppm file, send it to oled display
• gem ! ( actually, requiring onion-gpio.rb is sufficient)

TODO on V2 :

• develop a gpio library for digital input/output access
• develop a pwm library using fast-gpio
• OLED (text write, reset...)
• gem !

Feel free to collaborate to the project !

Ruby use on Omega2+

no difficulties :

> opkg intall ruby
> opkg install rubygems

This represent 5MB on flash memory, at /usr/lib/ruby.

~# du -s /usr/lib/ruby/*
5078    /usr/lib/ruby/2.4
156     /usr/lib/ruby/gems
5       /usr/lib/ruby/ruby2.4-bin
0       /usr/lib/ruby/site_ruby
0       /usr/lib/ruby/vendor_ruby

onion-gpio.rb

Use sysfs for access to digital gpio (duration: 3ms for writing one output line).

Use programs like fast-gpio, oled-exp an i2c-get for other access.

Example

# put a LED pn port 3,

require_relative 'ionion-gpio.rb'

gpio=OnionGpio.new( 3 , false)
gpio.setOutputDirection()
100.times { |i| gpio.setValue(i%2) ; sleep 0.1}
gpio.pwm( 1000, 50) # 1 KHz, 50% state on
gpio.pwm_reset 

# put a OLED on I2C SDA/SCL, : work with seeedStudio OLED grovve

oled=OnionOled.new(0,0)
oled.write_at(0,0,"Hello world...")

Oled clock :

########################################################################
#  oled : test oled
########################################################################
require_relative "onion-gpio"

def get_out(cmd,filter,nofield)
 `#{cmd}`.each_line {|line|
    next unless line=~ filter
    data=line.chomp.split(/\s+/)[nofield]
    ret= block_given? ? yield(data) : data
    return(ret) if ret
 }
 "?"
end

def getMem()   get_out("free",/^Mem:/,3)        {|m| m.to_i/1024} end
def getFlash() get_out("df -h",/^overlayfs:/,3)  end

oled=OnionOled.new(0,0)
oled.reset
oled.pos(0,0,ARGV.join(' ')) 
loop {
   oled.pos(10,5,Time.now.to_s.split(' ')[1])
   oled.pos(0,0, "FreeMem: #{getMem()} MB")
   oled.pos(0,1,"FreeFlash: #{getFlash()}")
   sleep 1
}