mahlon
07b2d81523
Stuff working well with a single 3-pin range finder. FossilOrigin-Name: 483d8caaef350827c026d7c234b026e9e720d26a7e27e54b0436f60b099a0ab9
121 lines
2.1 KiB
Ruby
Executable file
121 lines
2.1 KiB
Ruby
Executable file
# -*- ruby -*-
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# vim: set noet sta sw=4 ts=4 :
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require 'socket'
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require 'configurability'
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require 'loggability'
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require 'pathname'
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# A representation of a GPIO pin.
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# Manages basic reads/writes (HIGH/LOW).
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#
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class GPIO
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extend Configurability,
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Loggability
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# Default read timeout.
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TIMEOUT = 0.5
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# The sysfs path.
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BASE = Pathname( "/sys/class/gpio" )
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# Loggability API
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log_as :gpio
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### Instance a new GPIO at +pin+. It will be automatically exported.
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###
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def initialize( pin )
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@pin = pin
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@paths = {
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export: BASE + "export",
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unexport: BASE + "unexport",
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edge: BASE + "gpio#{pin}" + "edge",
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direction: BASE + "gpio#{pin}" + "direction",
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value: BASE + "gpio#{pin}" + "value"
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}
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self.export rescue Errno::EBUSY nil
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end
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# The GPIO PIN number.
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attr_reader :pin
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### Mark this pin as either input or output.
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###
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def mode( dir )
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case dir.to_sym
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when :in, :out
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self.set( :direction ) { dir.to_s }
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else
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raise "Mode must be :in or :out."
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end
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end
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### Hint at voltage measurement capture.
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###
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def edge( mode )
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case mode.to_sym
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when :none, :rising, :falling, :both
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self.set( :edge ) { mode.to_s }
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else
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raise "Edge must be one of: :none, :rising, :falling, or :both"
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end
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end
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### Tell the operating system to make this gpio available to sysfs.
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###
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def export
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self.set( :export ) { self.pin }
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end
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### Remove this gpio from sysfs.
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###
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def unexport
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self.set( :unexport ) { self.pin }
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end
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### Write a single +val+ to the GPIO.
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###
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def write( val )
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self.set( :value ) { val }
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end
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### Read a single value from the GPIO, with an optional timeout.
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###
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def read( timeout=TIMEOUT )
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io = @paths[ :value ].open
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ready = IO.select( [io], nil, nil, timeout )
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return unless ready # timeout
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rv = io.read( 1 ).to_i
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self.log.debug "Read %p from GPIO %d" % [ rv, self.pin ]
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return rv
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ensure
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io.close
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end
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#########
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protected
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#########
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### Generic write helper.
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###
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def set( path, &block )
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@paths[ path ].open( 'w' ) do |f|
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self.log.debug "Writing %p to %p of GPIO %d" % [ block.yield, path, self.pin ]
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f.puts( block.yield )
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end
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end
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end
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