Απορία: PWM (50 Hz) σε PIC16F887

[Stergios_[.gr]]

Έχω έναν pic16F887, χωρίς εξωτερικό ρολόι, από τον οποίον θέλω να βγάλω PWM (pulse-width modulation) συχνότητας 50Hz ώστε να οδηγήσω έναν σερβοκινητήρα.
Χρησιμοποιώντας MikroBasic, κ με συχνότητα ρολογιού δηλωμένη 8ΜΗΖ από την ΜΒ, μου βάζει error:

PWM1_Init(50) ' Initialize PWM1 module at 50Hz <--ARGUMENT OUT OF RANGE

Τι θα πρέπει να κάνω για να το καταφέρω?

Ευχαριστώ

Links:

• PIC16F887 @Microchip.com
• PIC16F88 Datasheet (.pdf)

[Stergios_[.gr]]

Ο κώδικας της MikroBasic τον οποίον προσπαθώ να γράψω:

program PWM_stergios
' * Description
'     This is simple test program to see how PWM library works. Using analog
'     input to read a potentiometer and sending the potentiometers value to
'     change the duty cycle of the PWM pulse on the CCP output pin (RC2).
'
' * Test configuration
'     MCU:            P16F887
'     Dev.Board:      44pin demo board
'     Oscillator:     internal

dim temp_res as word
dim temp_res8 as byte

  PWM1_Init(50)            ' Initialize PWM1 module at 50Hz
  Pwm_Start                  ' Start PWM

main:
  ANSEL  = %00000001         ' Configure AN0 pin as analog
  TRISA  = %00000001         ' PORTA is input
  PORTC =  $FF               ' Initialize PORTC

  while TRUE
    temp_res = ADC_Read(0)   ' Get 10-bit results of AD conversion
    temp_res8 = temp_res >> 8 ' use 8-bit
    Pwm1_Change_Duty(temp_res) ' Change duty ratio
  wend

end.

[Stergios_[.gr]]

ΛΥΘΗΚΕ:

program PWM_stergios
' * Description
'     This is simple test program to see how PWM library works. Using analog
'     input to read a potentiometer and sending the potentiometers value to
'     change the duty cycle of the PWM pulse on the CCP output pin (RC2).
'
' * Test configuration
'     MCU:            P16F887
'     Dev.Board:      44pin demo board
'     Oscillator:     internal

dim temp_res as word
dim temp_res8 as byte
  OSCCON = %001              ' Setting internal oscillator at 125Khz
  PWM1_Init(50)              ' Initialize PWM1 module at 50Hz
  Pwm_Start                  ' Start PWM

main:
  ANSEL  = %00000001         ' Configure AN0 pin as analog
  TRISA  = %00000001         ' PORTA is input
  PORTC =  $FF               ' Initialize PORTC

  while TRUE
    temp_res = ADC_Read(0)   ' Get 10-bit results of AD conversion
    temp_res8 = temp_res >> 8 ' use 8-bit
    Pwm1_Change_Duty(temp_res) ' Change duty ratio
  wend

end.