Class: PWM

Inherits:
Object
  • Object
show all
Defined in:
lib/adafruit-servo-driver/pwm.rb

Constant Summary collapse

MODE1 =

Registers

0x00
MODE2 = 
0x01
SUBADR1 = 
0x02
SUBADR2 = 
0x03
SUBADR3 = 
0x04
PRESCALE = 
0xFE
LED0_ON_L = 
0x06
LED0_ON_H = 
0x07
LED0_OFF_L = 
0x08
LED0_OFF_H = 
0x09
ALL_LED_ON_L = 
0xFA
ALL_LED_ON_H = 
0xFB
ALL_LED_OFF_L = 
0xFC
ALL_LED_OFF_H = 
0xFD
RESTART =

Bits

0x80
SLEEP = 
0x10
ALLCALL = 
0x01
INVRT = 
0x10
OUTDRV = 
0x04

Instance Method Summary collapse

Constructor Details

#initialize(address = 0x40, debug = false) ⇒ PWM

Returns a new instance of PWM.



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# File 'lib/adafruit-servo-driver/pwm.rb', line 27

def initialize(address=0x40, debug=false)
  # TODO detect pi revision
  @address = address
  @i2c = I2C.create('/dev/i2c-1')
  @debug = debug
  puts 'Reseting PCA9685 MODE1 (without SLEEP) and MODE2' if @debug
  setAllPWM(0, 0)
  @i2c.write(@address, MODE2, OUTDRV)
  @i2c.write(@address, MODE1, ALLCALL)
  sleep(0.005)           # wait for oscillator

  mode1 = @i2c.read(@address, 8, MODE1).unpack('C').first
  @i2c.write(@address, MODE1, ALLCALL)
  mode1 = mode1 & ~SLEEP # wake up (reset sleep)
  @i2c.write(@address, MODE1, mode1)
  sleep(0.005)           # wait for oscillator
end

Instance Method Details

#set_all_pwm(on, off) ⇒ Object Also known as: setAllPWM 



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# File 'lib/adafruit-servo-driver/pwm.rb', line 77

def set_all_pwm(on, off)
  @i2c.write(@address, ALL_LED_ON_L, on & 0xFF)
  @i2c.write(@address, ALL_LED_ON_H, on >> 8)
  @i2c.write(@address, ALL_LED_OFF_L, off & 0xFF)
  @i2c.write(@address, ALL_LED_OFF_H, off >> 8)
end

#set_pwm(channel, on, off) ⇒ Object Also known as: setPWM 



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# File 'lib/adafruit-servo-driver/pwm.rb', line 69

def set_pwm(channel, on, off)
  @i2c.write(@address, LED0_ON_L+4*channel, on & 0xFF)
  @i2c.write(@address, LED0_ON_H+4*channel, on >> 8)
  @i2c.write(@address, LED0_OFF_L+4*channel, off & 0xFF)
  @i2c.write(@address, LED0_OFF_H+4*channel, off >> 8)
end

#set_pwm_freq(freq) ⇒ Object Also known as: setPWMFreq 



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# File 'lib/adafruit-servo-driver/pwm.rb', line 45

def set_pwm_freq(freq)
  prescaleval = 25000000.0    # 25MHz
  prescaleval /= 4096.0       # 12-bit
  prescaleval /= Float(freq)
  prescaleval -= 1.0
  if @debug
    puts "Setting PWM frequency to #{freq} Hz"
    puts "Estimated pre-scale: #{prescaleval}"
  end
  prescale = (prescaleval + 0.5).floor
  if @debug
    puts "Final pre-scale: #{prescale}"
  end

  oldmode = @i2c.read(@address, 8, MODE1).unpack('C').first
  newmode = (oldmode & 0x7F) | 0x10    # sleep
  @i2c.write(@address, MODE1, newmode) # go to sleep
  @i2c.write(@address, PRESCALE, prescale)
  @i2c.write(@address, MODE1, oldmode)
  sleep(0.005)
  @i2c.write(@address, MODE1, oldmode | RESTART)
end