Datasheet

 2000-2013 Microchip Technology Inc. DS30569C-page 85
PIC16F870/871
10.5 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 mod-
ule 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.
10.6 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
configured as analog inputs.
The value that is in the ADRESH:ADRESL registers is
not modified for a Power-on Reset. The
ADRESH:ADRESL registers will contain unknown data
after a Power-on Reset.
TABLE 10-2: 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
INTCON GIE PEIE
T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u
0Ch PIR1
PSPIF
(1)
ADIF RCIF TXIF — CCP1IF TMR2IF TMR1IF 0000 -000 0000 -000
8Ch PIE1
PSPIE
(1)
ADIE RCIE TXIE — CCP1IE TMR2IE TMR1IE 0000 -000 0000 -000
1Eh ADRESH A/D Result Register High Byte xxxx xxxx uuuu uuuu
9Eh ADRESL A/D Result Register Low Byte xxxx xxxx uuuu uuuu
1Fh ADCON0 ADCS1 ADCS0 CHS2 CHS1 CHS0 GO/DONE
—ADON0000 00-0 0000 00-0
9Fh ADCON1 ADFM
— — —PCFG3PCFG2PCFG1PCFG0--0- 0000 --0- 0000
85h TRISA
— — PORTA Data Direction Register --11 1111 --11 1111
05h PORTA
— — PORTA Data Latch when written: PORTA pins when read --0x 0000 --0u 0000
89h
(1)
TRISE IBF OBF IBOV PSPMODE — PORTE Data Direction bits 0000 -111 0000 -111
09h
(1)
PORTE — — — — — RE2 RE1 RE0 ---- -xxx ---- -uuu
Legend: x = unknown, u = unchanged, - = unimplemented, read as '0'. Shaded cells are not used for A/D conversion.
Note 1: These registers/bits are not available on the 28-pin devices.