
2001 Microchip Technology Inc.
DS30292C-page 117
PIC16F87X
11.5
A/D Operation During SLEEP
The A/D module can operate during SLEEP mode. This
requires that the A/D clock source be set to RC
(ADCS1:ADCS0 =
11
). When the RC clock source is
selected, the A/D module waits one instruction cycle
before starting the conversion. This allows the
SLEEP
instruction to be executed, which eliminates all digital
switching noise from the conversion. When the conver-
sion is completed, the GO/DONE bit will be cleared and
the result loaded into the ADRES register. If the A/D
interrupt is enabled, the device will wake-up from
SLEEP. If the A/D interrupt is not enabled, the A/D
module will then be turned off, although the ADON bit
will remain set.
When the A/D clock source is another clock option (not
RC), a
SLEEP
instruction will cause the present conver-
sion to be aborted and the A/D module to be turned off,
though the ADON bit will remain set.
Turning off the A/D places the A/D module in its lowest
current consumption state.
11.6
Effects of a RESET
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. All A/D input pins are con-
figured as analog inputs.
The value that is in the ADRESH:ADRESL registers is
not
modified
for
a
ADRESH:ADRESL registers will contain unknown data
after a Power-on Reset.
Power-on
Reset.
The
TABLE 11-2:
REGISTERS/BITS ASSOCIATED WITH A/D
Note:
For the A/D module to operate in SLEEP,
the A/D clock source must be set to RC
(ADCS1:ADCS0 =
11
). To allow the con-
version to occur during SLEEP, ensure the
SLEEP
instruction immediately follows the
instruction that sets the GO/DONE bit.
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR,
BOR
Value on
MCLR,
WDT
0Bh,8Bh,
10Bh,18Bh
0Ch
8Ch
1Eh
9Eh
1Fh
9Fh
85h
05h
89h
(1)
09h
(1)
Legend:
Note
INTCON
GIE
PEIE
T0IE
INTE
RBIE
T0IF
INTF
RBIF
0000 000x 0000 000u
PIR1
PIE1
ADRESH
ADRESL
ADCON0
ADCON1
TRISA
PORTA
TRISE
PORTE
x
= unknown,
u
= unchanged,
-
= unimplemented, read as '0'. Shaded cells are not used for A/D conversion.
These registers/bits are not available on the 28-pin devices.
PSPIF
(1)
PSPIE
(1)
A/D Result Register High Byte
A/D Result Register Low Byte
ADCS1
ADCS0
ADFM
—
—
—
—
—
IBF
OBF
—
—
ADIF
ADIE
RCIF
RCIE
TXIF
TXIE
SSPIF
SSPIE
CCP1IF
CCP1IE
TMR2IF
TMR2IE TMR1IE
TMR1IF
0000 0000 0000 0000
0000 0000 0000 0000
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
CHS2
—
PORTA Data Direction Register
PORTA Data Latch when written: PORTA pins when read
IBOV
PSPMODE
—
—
—
—
CHS1
—
CHS0
PCFG3
GO/DONE
PCFG2
—
ADON
PCFG0
0000 00-0 0000 00-0
PCFG1
--0- 0000 --0- 0000
--11 1111 --11 1111
--0x 0000 --0u 0000
PORTE Data Direction bits
RE2
0000 -111 0000 -111
RE1
RE0
---- -xxx ---- -uuu
1: