PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 241

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

The analog reference voltage is software selectable to
either the device’s positive and negative supply voltage
(V
RA3/AN3/V
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.
The output of the sample and hold is the input into the
converter, which generates the result via successive
approximation.
FIGURE 20-1:
 2002 Microchip Technology Inc.
DD
and V
Note 1: Channels AN5 through AN7 are not available on PIC18F2X8 devices.
REF
2: All I/O pins have diode protection to V
Converter
SS
+ pin and RA2/AN2/V
10-bit
), or the voltage level on the
A/D
Reference
voltage
A/D BLOCK DIAGRAM
REF
V
V
REF
REF
- pin.
+
-
(Input Voltage)
V
AIN
Preliminary
PCFG0
DD
and V
V
DD
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.
Each port pin associated with the A/D converter can be
configured as an analog input (RA3 can also be a
voltage reference), or as a digital I/O.
The ADRESH and ADRESL registers contain the result
of the A/D conversion. When the A/D conversion is com-
plete, the result is loaded into the ADRESH/ADRESL
registers, the GO/DONE bit (ADCON0<2>) is cleared,
and A/D interrupt flag bit, ADIF, is set. The block
diagram of the A/D module is shown in Figure 20-1.
SS
.
V
SS
CHS2:CHS0
111
110
101
100
011
010
001
000
PIC18FXX8
DS41159B-page 239
AN1
AN7
AN2
AN0
AN6
AN5
AN4
AN3
(1)
(1)
(1)