PIC16F720-ESLASHML datasheet(79/244 Pages) MICROCHIP

79 / 244 page

 2010 Microchip Technology Inc.

DS41430A-page 79

PIC16F/LF720/721

FIGURE 9-2:

ANALOG-TO-DIGITAL CONVERSION TAD CYCLES

9.1.4

INTERRUPTS

The ADC module allows for the ability to generate an

interrupt upon completion of an Analog-to-Digital

conversion. The ADC Interrupt Flag is the ADIF bit in

the PIR1 register. The ADC Interrupt Enable is the

ADIE bit in the PIE1 register. The ADIF bit must be

cleared in software.

This interrupt can be generated while the device is

operating or while in Sleep. If the device is in Sleep, the

interrupt will wake-up the device. Upon waking from

Sleep, the next instruction following the SLEEP

instruction is always executed. If the user is attempting

to wake-up from Sleep and resume in-line code

execution, the GIE and PEIE bits of the INTCON

the INTCON register are enabled, execution will switch

to the Interrupt Service Routine.

Please refer to Section 9.1.4 “Interrupts” for more

information.

9.2

ADC Operation

9.2.1

STARTING A CONVERSION

To enable the ADC module, the ADON bit of the

ADCON0 register must be set to a ‘1’. Setting the GO/

DONE bit of the ADCON0 register to a ‘1’ will start the

Analog-to-Digital conversion.

9.2.2

COMPLETION OF A CONVERSION

When the conversion is complete, the ADC module will:

• Clear the GO/DONE bit

• Set the ADIF Interrupt Flag bit

• Update the ADRES register with new conversion

result

9.2.3

TERMINATING A CONVERSION

If a conversion must be terminated before completion,

the GO/DONE bit can be cleared in software. The

ADRES register will be updated with the partially com-

plete Analog-to-Digital conversion sample. Incomplete

bits will match the last bit converted.

TAD1

TAD2

TAD3

TAD4

TAD5

TAD6

TAD7

TAD8

TAD9

Set GO/DONE bit

Holding Capacitor is disconnected from Analog Input (typically 100 ns)

TCY to TAD

Conversion Starts

ADRES register is loaded,

GO/DONE bit is cleared,

ADIF bit is set,

Holding capacitor is connected to analog input

TAD0

Note 1: The ADIF bit is set at the completion of

every conversion, regardless of whether

or not the ADC interrupt is enabled.

2: The ADC operates during Sleep only

when the FRC oscillator is selected.

Note:

The GO/DONE bit should not be set in the

same instruction that turns on the ADC.

Refer to Section 9.2.6 “A/D Conversion

Procedure”.

Note:

A device Reset forces all registers to their

Reset state. Thus, the ADC module is

turned off and any pending conversion is

terminated.

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