index :: hw

hw.rpi.i2c.pca9685

aliases: [hw.rpi.pwm.pca9685]

driver for 16-channel 12-bit PWM module on PCA9685 chip for Raspberry Pi

available since version: 0.9.8

---

information

Note: default PWM freq is 50Hz Servo Control Many digital servos run on a 20ms pulse width (50Hz update frequency) based duty cycle, and do not utilize the entire pulse width for their control Typically, 2.5% of the 20ms pulse width (0.5ms) represents -90° offset, and 12.5% of the 20ms pulse width (2.5ms) represents +90° offset Be aware that driving some 180° servos too far past their -90°/+90° operational range can cause a little plastic limiter pin to break off and get stuck inside of the servo's gearing, which could potentially cause the servo to become jammed and no longer function Continuous servos operate in much the same fashion as 180° servos, but instead of the 2.5%/12.5% pulse width controlling a -90°/+90° offset it controls a -1x/+1x speed multiplier, with 0x being parked/no-movement and -1x/+1x being maximum speed in either direction.

arguments:

• I2C_BUS See @i2c_bus property
  type: atom
  

methods:

• const set channel constant value
  parameters:

  • CHAN device PWM channel. If equals to 16 means all channels
    type: int
    required: True
    

  • VALUE value
    type: bool
    required: True
    

  • [DELAY] the setting is delayed by the given phase value.
    type: float
    

• disable_prog_addr disable of using programmable address
  parameters:
  • TYPE prog address type
    type: atom
    required: True
    
• duty set channel PWM duty cycle
  parameters:

  • CHAN device PWM channel. If equals to 16 means all channels
    type: int
    required: True
    

  • DUTY duty cycle value
    type: float
    required: True
    

  • [PHASE] phase offset
    type: float
    

• enable enable/disable the device. The disabled state is equal to sleep, the device is keeping all current PWM setting, but just not responds to the new settings.
  parameters:
  • [STATE=1] new state
    type: bool
    

• enable_restart_and_disable put the controller to sleep while keeping the PWM register contents in preparation for a future restart
  

• freq set PWM frequency
  parameters:
  • FREQ new frequency
    type: float
    units: Hz
    required: True
    
• period set PWM period
  parameters:
  • PERIOD new frequency
    type: float
    units: ms
    required: True
    
• polarity set PWM inversed polarity. Applicable when OE = 0.
  parameters:
  • POLARITY polarity value: 0 - direct, 1 - inversed
    type: bool
    required: True
    
• pwidth set channel PWM pulse width
  parameters:

  • CHAN device PWM channel. If equals to 16 means all channels
    type: int
    required: True
    

  • WIDTH pulse width
    type: float
    units: ms
    required: True
    

  • [PHASE] phase offset
    type: float
    

• restart re-enable the controller after a sleep with restart enabled so that previously active PWM channels are restarted
  

• set_raw set channel raw PWM frequency
  parameters:

  • CHAN device PWM channel. If equals to 16 means all channels
    type: int
    required: True
    

  • ON ON counter time value
    type: int
    required: True
    

  • OFF OFF counter time value
    type: int
    required: True
    

• use_prog_addr set and use programmable address
  parameters:

  • TYPE prog address type
    type: atom
    required: True
    

  • I2C_ADDR new I²C address
    type: int
    required: True
    

properties:

• @i2c_addr (initonly) Get/set I²C address. Also 'default' value is accepted (for addr 0x40)
  type: int
  range: -4..119
  default: -1
  

• @i2c_bus (initonly) Get/set I²C bus
  type: atom
  enum: 1, 2, 3, 4, 5, 6, default, none
  default: none
  

inlets:

• control input
  type: control

outlets:

• control output
  type: control

keywords:

display pwm raspberry servo

Authors: Serge Poltavsky

License: GPL3 or later