PWM Motor Control Library

The PWM Motor Control module is available with a number of dsPIC30/33 MCUs. mikroBasic PRO for dsPIC30/33 and PIC24 provides a library which simplifies using the PWM Motor Control module.

Important :

Number of PWM modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.
PWM library routines require you to specify the module you want to use. To use the desired PWM module, simply change the letter x in the routine prototype for a number from 1 to 2.

PWMx_Mc_Init

Prototype	sub function PWMx_Mc_Init(dim freq_hz, pair_output_mode, enable_output_x, clock_prescale_output_postscale as word) as word
Description	Initializes the Motor Control PWM module with duty ratio 0. The function calculates timer period, writes it to the MCU's PTPER register and returns it as the function result.
Parameters	`freq_hz:` PWM frequency in Hz (refer to device datasheet for correct values in respect with Fosc) `pair_output_mode:` output mode for output pin pairs: `1` = independent, `0` = complementary. If `pair_output_mode.B0` is equal to 1 then PWM channels PWM1L and PWM1H will be independent, If `pair_output_mode.B1` is equal to 0 then PWM channels PWM2L and PWM2H will be complementary, ... If `pair_output_mode.Bn` is equal to 1 then PWM channels PWM(n+1)L and PWM(n+1)H will be independent, If `pair_output_mode.Bn` is equal to 0 then PWM channels PWM(n+1)L and PWM(n+1)H will be complementary. `enable_output_x:` bits <7..0> are enabling corresponding PWM channels <`PWM4H, PWM3H, PWM2H, PWM1H, PWM4L, PWM3L, PWM2L, PWM1L`>. If bit value is equal to `0` then corresponding PWM channel is disabled (pin is standard I/O). If bit value is equal to `1` then corresponding PWM channel is enabled (pin is PWM output). For detalied explanation consult the "Motor Control PWM Module" section in device datasheet `clock_prescale_output_postscale:` PWM clock prescaler/postscaler settings. Values `<0..3> and <0..15>` correspond to prescaler/postscaler `<1:1, 1:4, 1:16, 1:64> and <1:1, 1:2, ..., 1:16>`
Returns	Calculated timer period.
Requires	The dsPIC30/33 MCU must have the Motor Control PWM module.
Example	'Initializes the PWM1 module at 5KHz, complementary pin-pair output, output enabled on pins 4l..1l, no clock prescale and no clock postscale: dim duty_50 as word ... duty_50 = PWM1_Mc_Init(5000, 1, $0F, 0)
Notes	Number of PWM modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library. PWM library routines require you to specify the module you want to use. To use the desired PWM module, simply change the letter x in the routine prototype for a number from 1 to 2.

PWMx_Mc_Set_Duty

Prototype	sub procedure PWM1_Mc_Set_Duty(dim duty, channel as word) ' For dsPIC 33FJ MCUs that have PWM2 module : sub procedure PWM2_Mc_Set_Duty(dim duty as word)
Description	The function changes PWM duty ratio.
Parameters	`duty:` PWM duty ratio. Valid values: `0` to timer period returned by the PWMx_Mc_Init function. `channel:` number of PWM channel to change duty to.
Returns	Nothing.
Requires	The dsPIC30/33 MCU must have the Motor Control PWM module. The PWM module needs to be initalized. See the PWMx_Mc_Init function.
Example	' Set duty ratio to 50% at channel 1: PWM1_Mc_Init(5000,1,$F,0) ... PWM1_Mc_Set_Duty(32767, 1)
Notes	Number of PWM modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library. PWM library routines require you to specify the module you want to use. To use the desired PWM module, simply change the letter x in the routine prototype for a number from 1 to 2.

PWMx_Mc_Start

Prototype	sub procedure PWMx_Mc_Start()
Description	Starts the Motor Control PWM module (channels initialized in the PWMx_Mc_Init function).
Parameters	None.
Returns	Nothing.
Requires	The dsPIC30/33 MCU must have the Motor Control PWM module. The PWM module needs to be initalized. See the PWMx_Mc_Init function.
Example	' start the Motor Control PWM1 module PWM1_Mc_Start()
Notes	Number of PWM modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library. PWM library routines require you to specify the module you want to use. To use the desired PWM module, simply change the letter x in the routine prototype for a number from 1 to 2.

PWMx_Mc_Stop

Prototype	sub procedure PWMx_Mc_Stop()
Description	Stops the Motor Control PWM module.
Parameters	None.
Returns	Nothing.
Requires	The dsPIC30/33 MCU must have the Motor Control PWM module.
Example	' stop the Motor Control PWM1 module PWM1_Mc_Stop()
Notes	Number of PWM modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library. PWM library routines require you to specify the module you want to use. To use the desired PWM module, simply change the letter x in the routine prototype for a number from 1 to 2.

Library Example

The example changes PWM duty ratio on channel 1 continually. If LED is connected to the channel 1, a gradual change of emitted light will be noticeable.

Copy Code To Clipboard

program PWM

dim pwm_period, current_duty as word

main:

  ADPCFG = 0xFFFF                               ' initialize AN pins as digital
  PORTB  = 0
  TRISB  = 0                                    ' initialize portb as output
  current_duty = 10
  Delay_ms(1000)

  pwm_period = PWM1_MC_Init(5000, 1, 0x01, 0)   ' Pwm_Mc_Init returns calculated timer period.
  PWM1_MC_Set_Duty(current_duty, 1)
  PWM1_MC_Start()

  while (TRUE)                                  ' Endless loop
    if (RB0_bit) then                           ' Button on RB0 pressed
      Delay_ms(20)
      Inc(current_duty)                         ' Increment current_duty
      if (current_duty > pwm_period) then       ' If we increase current_duty greater then possible pwm_period value
        current_duty = 0                        ' reset current_duty value to zero
      end if
      PWM1_MC_Set_Duty(current_duty,  1)        ' Set newly acquired duty ratio
    end if

    if (RB1_bit) then                           ' Button on RB1 pressed
      Delay_ms(20)
      Dec(current_duty)                         ' Decrement current_duty
      if (current_duty > pwm_period) then       ' If we decrease current_duty greater then possible pwm_period value (overflow)
        current_duty = pwm_period               ' set current_duty to max possible value
      end if
      PWM1_MC_Set_Duty(current_duty,  1)        ' Set newly acquired duty ratio
    end if
    Delay_ms(5)                                 ' Slow down change pace a little
  wend
end.

HW Connection

PWM Motor Control demonstration

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