PIC16C717-I/SS View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16C717-I/SS

18/20-Pin, 8-Bit CMOS Microcontrollers with 10/12-Bit A/D

Microchip Technology 

11.0 ANALOG-TO-DIGITAL

CONVERTER (A/D) MODULE

The analog-to-digital (A/D) converter module has six

inputs for the PIC16C717/770/771.

The PIC16C717 analog-to-digital converter (A/D)

allows conversion of an analog input signal to a corre-

sponding 10-bit digital value, while the A/D converter

in the PIC16C770/771 allows conversion to a corre-

sponding 12-bit digital value. The A/D module has up

to 6 analog inputs, which are multiplexed into one

sample and hold. The output of the sample and hold is

the input into the converter, which generates the result

via successive approximation. The analog reference

voltages are software selectable to either the device’s

analog positive and negative supply voltages (AVDD/

AVSS), the voltage level on the VREF+ and VREF- pins,

or internal voltage references if enabled (VRH, VRL).

The A/D converter can be triggered by setting the GO/

DONE bit, or by the special event compare mode of

the ECCP1 module. When conversion is complete, the

GO/DONE bit returns to ’0’, the ADIF bit in the PIR1

register is set, and an A/D interrupt will occur, if

enabled.

The A/D converter has a unique feature of being able to

operate while the device is in SLEEP mode. To operate

in sleep, the A/D conversion clock must be derived from

the A/D’s internal RC oscillator.

PIC16C717/770/771

The A/D module has four registers. These registers

are:

• A/D Result Register Low ADRESL

• A/D Result Register High ADRESH

• A/D Control Register 0 (ADCON0)

• A/D Control Register 1 (ADCON1)

A device reset forces all registers to their reset state.

This forces the A/D module to be turned off and any

conversion is aborted.

11.1 Control Registers

The ADCON0 register, shown in Register 11-1, con-

trols the operation of the A/D module. The ADCON1

register, shown in Register 11-2, configures the func-

tions of the port pins, the voltage reference configura-

tion and the result format. The port pins can be

configured as analog inputs or as digital I/O.

The combination of the ADRESH and ADRESL regis-

ters contain the result of the A/D conversion. The reg-

ister pair is referred to as the ADRES register. When

the A/D conversion is complete, the result is loaded

into ADRES, the GO/DONE bit (ADCON0<2>) is

cleared, and the A/D interrupt flag ADIF is set. The

block diagram of the A/D module is shown in

Figure 11-3.

© 1999 Microchip Technology Inc.

Advanced Information

DS41120A-page 113

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