PIC17C756A MICROCHIP [Microchip Technology], PIC17C756A Datasheet - Page 181

• Manufacturer Part Number: PIC17C756A
• Description: High-Performance 8-bit CMOS EPROM Microcontrollers with 10-bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

The ADRESH:ADRESL registers contain the 10-bit
result of the A/D conversion. When the A/D conversion
is complete, the result is loaded into this A/D result reg-
ister pair, the GO/DONE bit (ADCON0<2>) is cleared
and A/D interrupt flag bit, ADIF is set. The block
diagrams of the A/D module are shown in Figure 16-1.
After the A/D module has been configured as desired,
the selected channel must be acquired before the con-
version is started. The analog input channels must
have their corresponding DDR bits selected as inputs.
To determine sample time, see Section 16.1. After this
acquisition time has elapsed, the A/D conversion can
be started. The following steps should be followed for
doing an A/D conversion:
1.
FIGURE 16-1:
2000 Microchip Technology Inc.
Configure the A/D module:
a)
b)
c)
d)
Configure analog pins/voltage reference/
and digital I/O (ADCON1)
Select A/D input channel (ADCON0)
Select A/D conversion clock (ADCON0)
Turn on A/D module (ADCON0)
Note 1: These channels are only available on PIC16C76X devices.
Converter
A/D
(Reference
Voltage)
A/D BLOCK DIAGRAM
V
V
REF
REF
+
-
(Input Voltage)
V
IN
PCFG0
AV
DD
2.
3.
4.
5.
6.
7.
AV
Configure A/D interrupt (if desired):
a)
b)
c)
Wait the required acquisition time.
Start conversion:
a)
Wait for A/D conversion to complete, by either:
a)
OR
b)
Read
(ADRESH:ADRESL), clear bit ADIF, if required.
For next conversion, go to step 1 or step 2, as
required. The A/D conversion time per bit is
defined as T
required before next acquisition starts.
SS
Clear ADIF bit
Set ADIE bit
Clear GLINTD bit
Set GO/DONE bit (ADCON0)
Polling for the GO/DONE bit to be cleared
Waiting for the A/D interrupt
CHS3:CHS0
A/D
AD
1010
1001
1000
0001
0000
1011
1011
1011
1011
1011
0111
0110
0101
0100
0011
0010
. A minimum wait of 2T
Result
PIC17C7XX
DS30289B-page 181
register
AN1/V
AN0/V
AN15
AN14
AN13
AN12
AN11
AN10
AN9
AN8
AN7
AN6
AN5
AN4
AN3
AN2
(1)
(1)
(1)
(1)
REF
REF
AD
-
+
pair
is