MikroElektronika books

Example 6 – Realization of pulse width modulation

The example shows the realization of continuously varying pulse width modulation (PWM). The continously modulated output is on the PORTE.0 pin which is monitored by a LED diode. The realization is carried out by using the mikroBasic compiler for dsPIC30F microcontrollers. Fig. 13-6 shows the electric diagram of the realized continuous PWM of a LED diode connected to PORTE.0.

pic-microcontrollers-programming-dspic-in-basic-chapter-13-image--6
Fig. 13-6 The electric diagram of the realized continuous PWM of a LED diode connected to PORTE.0.
program MC_PWM_Test

dim i, duty_50 as word

main:
  ADPCFG = 0xFFFF
  TRISE  = 0
  PORTB  = 0xAAAA
  TRISB  = 0
  Delay_ms(1000)

  duty_50 = Pwm_Mc_Init(5000,1,0x01,0)        ' Pwm_Mc_Init returns 50% of the duty
  i = duty_50
  Pwm_Mc_Set_Duty(i, 1)
  Pwm_Mc_Start()

  while true
    i = i - 1
    Pwm_Mc_Set_Duty(i,1)
    Delay_ms(1)
    if (i = 0) then
      i = duty_50 * 2 - 1                     ' Do not allow the overflow
    end if
    PORTB = i
  wend
end.