MikroElektronika PIC Microcontrollers PIC18 Manuel d'utilisateur télécharger pdf (Page 62)

62l Robotics experiment with PIC microcontroller

5.4.5 Result formatting

The A/D converter result will store in a pair of regeter; ADRESH:ADRESL. They will

keep the data format following the selection of ADFM bit.

If Left justified is selected (ADFM = ‘0’), ADRESH register keeps 8 upper bits

and ADRESL register keeps 2 lower bits.

If Right justified is selected (ADFM = ‘1’), ADRESH register keeps 2 upper bits

and ADRESL register keeps 8 lower bits.

b b b b b b b b b b 0 0 0 0 0 0

10-bit Result

# " !    ' & % $ # " !  

ADFM = “0” Left justified result

b b b b b b b b b b0 0 0 0 0 0

10-bit Result

# " !    ' & % $ # " !  

ADFM = “1” Right justified result

The result data format from ADFM bit selection of ADCON1 register

5.5 A/D Conversion procedure

This is an example procedure for using the ADC to perform an Analog-to-Digital

conversion pf PIC16F887 microcontroller:

1. Configure Port:

l Disable pin output driver

l Configure pin as analog by setting ANSEL or ANSELH register

2. Configure the ADC module (by setting ADCON0 register) :

l Select ADC conversion clock

l Configure voltage reference

l Select ADC input channel

l Select result format by setting ADCON1 register

l Turn on ADC module

3. Configure ADC interrupt (optional):

l Clear ADC interrupt flag

l Enable ADC interrupt

l Enable peripheral interrupt

l Enable global interrupt.

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MikroElektronika PIC Microcontrollers PIC18 Manuel d'utilisateur Page 62