Class: I2CDevice::Driver::GPIO

Inherits:
Base
  • Object
show all
Defined in:
lib/templates/grove_pi/i2c/driver/gpio.rb

Overview

Generic software I2C Driver based on /sys/class/gpio. THIS MODULE WORKS WITH VERY SLOW SPEED ABOUT JUST 1kHz (normaly 100kHz).

Constant Summary collapse

@@DEBUG = 
false

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ GPIO

opts[:sda]
Integer

Pin-number of SDA

opts[:scl]
Integer

Pin-number of SCL

[ opts[:speed] = 1 ]
Integer

Clock speed in kHz



90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 90

def initialize(opts={})
  @sda = opts[:sda] or raise "opts[:sda] = [gpio pin number] is required"
  @scl = opts[:scl] or raise "opts[:scl] = [gpio pin number] is required"
  @speed = opts[:speed] || 1 # kHz but insane
  @clock = 1.0 / (@speed * 1000)

  begin
    GPIO.export(@sda)
    GPIO.export(@scl)
  rescue Errno::EBUSY => e
  end
  ObjectSpace.define_finalizer(self, self.class.finalizer([@scl, @sda]))
  begin
    GPIO.direction(@sda, :high)
    GPIO.direction(@scl, :high)
    GPIO.direction(@sda, :in)
    GPIO.direction(@scl, :in)
  rescue Errno::EACCES => e # writing to gpio after export is failed in a while
    retry
  end
end

Instance Attribute Details

#scl ⇒ Object (readonly)

Pin-number of SCL



83
84
85
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 83

def scl
  @scl
end

#sda ⇒ Object (readonly)

Pin-number of SDA



81
82
83
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 81

def sda
  @sda
end

#speed ⇒ Object (readonly)

Clock speed in kHz



85
86
87
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 85

def speed
  @speed
end

Class Method Details

.direction(pin, direction) ⇒ Object

:nodoc:



35
36
37
38
39
40
41
42
43
44
45
46
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 35

def self.direction(pin, direction) #:nodoc: 
  # [:in, :out, :high, :low].include?(direction) or raise "direction must be :in, :out, :high or :low"
  File.open("/sys/class/gpio/gpio#{pin}/direction", "w") do |f|
    begin
      f.flock(File::LOCK_EX)
      f.syswrite(direction)
      f.flock(File::LOCK_UN)
    rescue
      f.flock(File::LOCK_UN)
    end
  end
end

.export(pin) ⇒ Object

:nodoc:



11
12
13
14
15
16
17
18
19
20
21
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 11

def self.export(pin) #:nodoc: 
  File.open("/sys/class/gpio/export", "w") do |f|
    begin
      f.flock(File::LOCK_EX)
      f.syswrite(pin)
      f.flock(File::LOCK_UN)
    rescue
      f.flock(File::LOCK_UN)
    end
  end
end

.finalizer(ports) ⇒ Object

:nodoc:



72
73
74
75
76
77
78
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 72

def self.finalizer(ports)  #:nodoc: 
  proc do
    ports.each do |pin|
      GPIO.unexport(pin)
    end
  end
end

.read(pin) ⇒ Object

:nodoc:



48
49
50
51
52
53
54
55
56
57
58
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 48

def self.read(pin) #:nodoc: 
  File.open("/sys/class/gpio/gpio#{pin}/value", "r") do |f|
    begin
      f.flock(File::LOCK_EX)
      f.sysread(1).to_i
      f.flock(File::LOCK_UN)
    rescue
      f.flock(File::LOCK_UN)
    end
  end
end

.unexport(pin) ⇒ Object

:nodoc:



23
24
25
26
27
28
29
30
31
32
33
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 23

def self.unexport(pin) #:nodoc: 
  File.open("/sys/class/gpio/unexport", "w") do |f|
    begin
      f.flock(File::LOCK_EX)
      f.syswrite(pin)
      f.flock(File::LOCK_UN)
    rescue
      f.flock(File::LOCK_UN)
    end
  end
end

.write(pin, val) ⇒ Object

:nodoc:



60
61
62
63
64
65
66
67
68
69
70
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 60

def self.write(pin, val) #:nodoc: 
  File.open("/sys/class/gpio/gpio#{pin}/value", "w") do |f|
    begin
      f.flock(File::LOCK_EX)
      f.syswrite(val ? "1" : "0")
      f.flock(File::LOCK_UN)
    rescue
      f.flock(File::LOCK_UN)
    end
  end
end

Instance Method Details

#i2cget(address, param, length = 1) ⇒ Object

Interface of I2CDevice::Driver



113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 113

def i2cget(address, param, length=1)
  ret = ""
  start_condition
  unless write( (address << 1) + 0)
    raise I2CDevice::I2CIOError, "Unknown slave device (address:#{address})"
  end
  write(param)
  stop_condition # AVR stucked with SCL low without this (Does not AVR support Sr condition?)
  start_condition
  unless write( (address << 1) + 1)
    raise I2CDevice::I2CIOError, "Unknown slave device (address:#{address})"
  end
  length.times do |n|
    ret << read(n != length - 1).chr
  end
  ret
ensure
  stop_condition
end

#i2cset(address, *data) ⇒ Object

Interface of I2CDevice::Driver



134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
 
# File 'lib/templates/grove_pi/i2c/driver/gpio.rb', line 134

def i2cset(address, *data)
  sent = 0
  start_condition
  unless write( (address << 1) + 0)
    raise I2CDevice::I2CIOError, "Unknown slave device (address:#{address})"
  end
  data.each do |c|
    unless write(c)
      break
    end
    sent += 1
  end
  sent
ensure
  stop_condition
end