PIC16C71X
The A/D converter has a unique feature of being able
to operate while the device is in SLEEP mode.To oper-
ate in sleep, the A/D conversion clock must be derived
from the A/D’s internal RC oscillator.
7.0
ANALOG-TO-DIGITAL
CONVERTER (A/D) MODULE
Applicable Devices 710 71 711 715
The A/D module has three registers. These registers
are:
The analog-to-digital (A/D) converter module has four
analog inputs.
• A/D Result Register (ADRES)
• A/D Control Register 0 (ADCON0)
• A/D Control Register 1 (ADCON1)
The A/D allows conversion of an analog input signal to
a corresponding 8-bit digital number (refer to Applica-
tion Note AN546 for use of A/D Converter). The output
of the sample and hold is the input into the converter,
which generates the result via successive approxima-
tion. The analog reference voltage is software select-
able to either the device’s positive supply voltage (VDD)
or the voltage level on the RA3/AN3/VREF pin.
The ADCON0 register, shown in Figure 7-1 and
Figure 7-2, controls the operation of the A/D module.
The ADCON1 register, shown in Figure 7-3 configures
the functions of the port pins.The port pins can be con-
figured as analog inputs (RA3 can also be a voltage ref-
erence) or as digital I/O.
FIGURE 7-1: ADCON0 REGISTER (ADDRESS 08h), PIC16C710/71/711
R/W-0 R/W-0
ADCS1 ADCS0
U-0
R/W-0
CHS1
R/W-0
R/W-0
R/W-0
ADIF
R/W-0
ADON
(1)
CHS0 GO/DONE
R =Readable bit
W = Writable bit
U =Unimplemented
bit, read as ‘0’
—
bit7
bit0
- n =Value at POR reset
bit 7-6: ADCS1:ADCS0: A/D Conversion Clock Select bits
00= FOSC/2
01= FOSC/8
10= FOSC/32
11= FRC (clock derived from an RC oscillation)
bit 5:
Unimplemented: Read as '0'.
bit 4-3: CHS1:CHS0: Analog Channel Select bits
00= channel 0, (RA0/AN0)
01= channel 1, (RA1/AN1)
10= channel 2, (RA2/AN2)
11= channel 3, (RA3/AN3)
bit 2:
GO/DONE: A/D Conversion Status bit
If ADON = 1:
1 = A/D conversion in progress (setting this bit starts the A/D conversion)
0 = A/D conversion not in progress (This bit is automatically cleared by hardware when the A/D conver-
sion is complete)
bit 1:
bit 0:
ADIF: A/D Conversion Complete Interrupt Flag bit
1 = conversion is complete (must be cleared in software)
0 = conversion is not complete
ADON: A/D On bit
1 = A/D converter module is operating
0 = A/D converter module is shutoff and consumes no operating current
Note 1: Bit5 of ADCON0 is a General Purpose R/W bit for the PIC16C710/711 only. For the PIC16C71, this bit is
unimplemented, read as '0'.
1997 Microchip Technology Inc.
DS30272A-page 37
MICROCHIP [ MICROCHIP ]
