Module: Beaglebone::PWM
- Defined in:
- lib/beaglebone/pwm.rb
Overview
PWM
procedural methods for PWM control
Summary
#start is called to enable a PWM pin
Constant Summary collapse
- POLARITIES =
Polarity hash
{ :NORMAL => 0, :INVERTED => 1 }
Class Method Summary collapse
-
.cleanup ⇒ Object
reset all PWM pins we’ve used to IN and unexport them.
-
.disable_pwm_pin(pin) ⇒ Object
Disable a PWM pin.
-
.enabled?(pin) ⇒ Boolean
Returns true if specified pin is enabled in PWM mode, else false.
-
.get_pwm_pins ⇒ Array<Symbol>
Return an array of PWM pins in use.
-
.run(pin) ⇒ Object
Start PWM output on specified pin.
-
.set_duty_cycle(pin, duty, newperiod = nil) ⇒ Object
Set duty cycle of specified pin in percentage.
-
.set_duty_cycle_ns(pin, duty) ⇒ Object
Set duty cycle of specified pin in nanoseconds.
-
.set_frequency(pin, frequency) ⇒ Object
Set frequency of specified pin in cycles per second.
-
.set_period_ns(pin, period) ⇒ Object
Set frequency of specified pin based on period duration.
-
.set_polarity(pin, polarity) ⇒ Object
Set polarity on specified pin.
-
.start(pin, duty = nil, frequency = nil, polarity = nil, run = true) ⇒ Object
Initialize a PWM pin.
-
.stop(pin) ⇒ Object
Stop PWM output on specified pin.
Class Method Details
.cleanup ⇒ Object
reset all PWM pins we’ve used to IN and unexport them
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# File 'lib/beaglebone/pwm.rb', line 286 def cleanup get_pwm_pins.each { |x| disable_pwm_pin(x) } end |
.disable_pwm_pin(pin) ⇒ Object
Disable a PWM pin
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# File 'lib/beaglebone/pwm.rb', line 303 def disable_pwm_pin(pin) Beaglebone::check_valid_pin(pin, :pwm) Beaglebone::delete_pin_status(pin) if Beaglebone::device_tree_unload("#{TREES[:PWM][:pin]}#{pin}") end |
.enabled?(pin) ⇒ Boolean
Returns true if specified pin is enabled in PWM mode, else false
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# File 'lib/beaglebone/pwm.rb', line 73 def enabled?(pin) return true if Beaglebone::get_pin_status(pin, :type) == :pwm return false unless valid?(pin) if Dir.exists?(pwm_directory(pin)) start(pin, nil, nil, nil, false) return true end false end |
.get_pwm_pins ⇒ Array<Symbol>
Return an array of PWM pins in use
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# File 'lib/beaglebone/pwm.rb', line 296 def get_pwm_pins Beaglebone.pinstatus.clone.select { |x,y| x if y[:type] == :pwm}.keys end |
.run(pin) ⇒ Object
Start PWM output on specified pin. Pin must have been previously started
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# File 'lib/beaglebone/pwm.rb', line 109 def run(pin) Beaglebone::check_valid_pin(pin, :pwm) return false unless enabled?(pin) raise StandardError, "Pin is not PWM enabled: #{pin}" unless Beaglebone::get_pin_status(pin, :type) == :pwm run_fd = Beaglebone::get_pin_status(pin, :fd_run) raise StandardError, "Pin is not PWM enabled: #{pin}" unless run_fd run_fd.write('1') run_fd.flush raise StandardError, "Could not start PWM: #{pin}" unless read_run_value(pin) == 1 true end |
.set_duty_cycle(pin, duty, newperiod = nil) ⇒ Object
Set duty cycle of specified pin in percentage
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# File 'lib/beaglebone/pwm.rb', line 154 def set_duty_cycle(pin, duty, newperiod=nil) raise ArgumentError, "Duty cycle must be >= 0 and <= 100, #{duty} invalid" if duty < 0 || duty > 100 check_pwm_enabled(pin) fd = Beaglebone::get_pin_status(pin, :fd_duty) raise StandardError, "Pin is not PWM enabled: #{pin}" unless fd period = newperiod || Beaglebone::get_pin_status(pin, :period) value = ((duty * period) / 100.0).round fd.write(value.to_s) fd.flush raise StandardError, "Could not set duty cycle: #{pin} (#{value})" unless read_duty_value(pin) == value Beaglebone::set_pin_status(pin, :duty_pct, duty) value end |
.set_duty_cycle_ns(pin, duty) ⇒ Object
Set duty cycle of specified pin in nanoseconds
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# File 'lib/beaglebone/pwm.rb', line 184 def set_duty_cycle_ns(pin, duty) check_pwm_enabled(pin) fd = Beaglebone::get_pin_status(pin, :fd_duty) raise StandardError, "Pin is not PWM enabled: #{pin}" unless fd period = Beaglebone::get_pin_status(pin, :period) duty = duty.to_i if duty < 0 || duty > period raise ArgumentError, "Duty cycle ns must be >= 0 and <= #{period} (current period), #{duty} invalid" end value = duty fd.write(value.to_s) fd.flush #since we're setting the duty_ns, we want to update the duty_pct value as well here. raise StandardError, "Could not set duty cycle: #{pin} (#{value})" unless read_duty_value(pin, true) == value value end |
.set_frequency(pin, frequency) ⇒ Object
Set frequency of specified pin in cycles per second
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# File 'lib/beaglebone/pwm.rb', line 216 def set_frequency(pin, frequency) frequency = frequency.to_i raise ArgumentError, "Frequency must be > 0 and <= 1000000000, #{frequency} invalid" if frequency < 1 || frequency > 1000000000 check_pwm_enabled(pin) fd = Beaglebone::get_pin_status(pin, :fd_period) raise StandardError, "Pin is not PWM enabled: #{pin}" unless fd duty_ns = Beaglebone::get_pin_status(pin, :duty) duty_pct = Beaglebone::get_pin_status(pin, :duty_pct) value = (1000000000 / frequency).round #we can't set the frequency lower than the previous duty cycle #adjust if necessary if duty_ns > value set_duty_cycle(pin, Beaglebone::get_pin_status(pin, :duty_pct), value) end fd.write(value.to_s) fd.flush raise StandardError, "Could not set frequency: #{pin} (#{value})" unless read_period_value(pin) == value #adjust the duty cycle if we haven't already if duty_ns <= value set_duty_cycle(pin, duty_pct, value) end value end |
.set_period_ns(pin, period) ⇒ Object
Set frequency of specified pin based on period duration
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# File 'lib/beaglebone/pwm.rb', line 255 def set_period_ns(pin, period) period = period.to_i raise ArgumentError, "period must be > 0 and <= 1000000000, #{period} invalid" if period < 1 || period > 1000000000 check_pwm_enabled(pin) fd = Beaglebone::get_pin_status(pin, :fd_period) raise StandardError, "Pin is not PWM enabled: #{pin}" unless fd duty_ns = Beaglebone::get_pin_status(pin, :duty) value = period.to_i #we can't set the frequency lower than the previous duty cycle #adjust if necessary if duty_ns > value set_duty_cycle(pin, Beaglebone::get_pin_status(pin, :duty_pct), value) end fd.write(value.to_s) fd.flush raise StandardError, "Could not set period: #{pin} (#{value})" unless read_period_value(pin) == value #adjust the duty cycle if we haven't already if duty_ns <= value set_duty_cycle(pin, Beaglebone::get_pin_status(pin, :duty_pct), value) end value end |
.set_polarity(pin, polarity) ⇒ Object
Set polarity on specified pin
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# File 'lib/beaglebone/pwm.rb', line 134 def set_polarity(pin, polarity) check_valid_polarity(polarity) check_pwm_enabled(pin) polarity_fd = Beaglebone::get_pin_status(pin, :fd_polarity) raise StandardError, "Pin is not PWM enabled: #{pin}" unless polarity_fd polarity_fd.write(POLARITIES[polarity.to_sym].to_s) polarity_fd.flush raise StandardError, "Could not set polarity: #{pin}" unless read_polarity_value(pin) == POLARITIES[polarity.to_sym] end |
.start(pin, duty = nil, frequency = nil, polarity = nil, run = true) ⇒ Object
Initialize a PWM pin
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# File 'lib/beaglebone/pwm.rb', line 25 def start(pin, duty=nil, frequency=nil, polarity=nil, run=true) #make sure the pwm controller dtb is loaded Beaglebone::device_tree_load(TREES[:PWM][:global]) Beaglebone::check_valid_pin(pin, :pwm) #if pin is enabled for something else, disable it if Beaglebone::get_pin_status(pin) && Beaglebone::get_pin_status(pin, :type) != :pwm Beaglebone::disable_pin(pin) end #load device tree for pin if not already loaded unless Beaglebone::get_pin_status(pin, :type) == :pwm Beaglebone::device_tree_load("#{TREES[:PWM][:pin]}#{pin}", 0.5) Beaglebone::set_pin_status(pin, :type, :pwm) end duty_fd = File.open("#{pwm_directory(pin)}/duty", 'r+') period_fd = File.open("#{pwm_directory(pin)}/period", 'r+') polarity_fd = File.open("#{pwm_directory(pin)}/polarity", 'r+') run_fd = File.open("#{pwm_directory(pin)}/run", 'r+') Beaglebone::set_pin_status(pin, :fd_duty, duty_fd) Beaglebone::set_pin_status(pin, :fd_period, period_fd) Beaglebone::set_pin_status(pin, :fd_polarity, polarity_fd) Beaglebone::set_pin_status(pin, :fd_run, run_fd) read_period_value(pin) read_duty_value(pin) read_polarity_value(pin) run_fd.write('0') run_fd.flush set_polarity(pin, polarity) if polarity set_frequency(pin, frequency) if frequency set_duty_cycle(pin, duty) if duty if run run_fd.write('1') run_fd.flush end raise StandardError, "Could not start PWM: #{pin}" unless read_run_value(pin) == 1 true end |
.stop(pin) ⇒ Object
Stop PWM output on specified pin
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# File 'lib/beaglebone/pwm.rb', line 88 def stop(pin) Beaglebone::check_valid_pin(pin, :pwm) return false unless enabled?(pin) raise StandardError, "Pin is not PWM enabled: #{pin}" unless Beaglebone::get_pin_status(pin, :type) == :pwm run_fd = Beaglebone::get_pin_status(pin, :fd_run) raise StandardError, "Pin is not PWM enabled: #{pin}" unless run_fd run_fd.write('0') run_fd.flush raise StandardError, "Could not stop PWM: #{pin}" unless read_run_value(pin) == 0 true end |