Datasheet

© 2007 Microchip Technology Inc. DS41232D-page 49
PIC12F635/PIC16F636/639
REGISTER 4-3: WDA: WEAK PULL-UP/PULL-DOWN DIRECTION REGISTER
U-0 U-0 R/W-1 R/W-1 U-0 R/W-1 R/W-1 R/W-1
— — WDA5 WDA4 — WDA2 WDA1 WDA0
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 7-6 Unimplemented: Read as ‘0’
bit 5-4 WDA<5:4>: Pull-up/Pull-down Selection bits
1 = Pull-up selected
0 = Pull-down selected
bit 3 Unimplemented: Read as ‘0’
bit 2-0 WDA<2:0>: Pull-up/Pull-down Selection bits
1 = Pull-up selected
0 = Pull-down selected
Note 1: The weak pull-up/pull-down device is enabled only when the global RAPU
bit is enabled, the pin is in Input mode (TRIS
= 1), the individual WDA bit is enabled (WDA = 1) and the pin is not configured as an analog input or clock function.
2: RA3 pull-up is enabled when the pin is configured as MCLR
in the Configuration Word register and the device is not in
Programming mode.
REGISTER 4-4: WPUDA: WEAK PULL-UP/PULL-DOWN ENABLE REGISTER
U-0 U-0 R/W-1 R/W-1 U-0 R/W-1 R/W-1 R/W-1
— — WPUDA5
(3)
WPUDA4
(3)
— WPUDA2 WPUDA1 WPUDA0
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 7-6 Unimplemented: Read as ‘0’
bit 5-4 WPUDA<5:4>: Pull-up/Pull-down Direction Selection bits
(3)
1 = Pull-up/pull-down enabled
0 = Pull-up/pull-down disabled
bit 3 Unimplemented: Read as ‘0’
bit 2-0 WPUDA<2:0>: Pull-up/Pull-down Direction Selection bits
1 = Pull-up/pull-down enabled
0 = Pull-up/pull-down disabled
Note 1: The weak pull-up/pull-down direction device is enabled only when the global RAPU
bit is enabled, the pin is in Input mode
(TRIS = 1), the individual WPUDA bit is enabled (WPUDA = 1) and the pin is not configured as an analog input or clock
function.
2: RA3 pull-up is enabled when the pin is configured as MCLR
in the Configuration Word register and the device is not in
Programming mode.
3: WPUDA5 bit can be written if INTOSC is enabled and T1OSC is disabled; otherwise, the bit can not be written and reads
as ‘1’. WPUDA4 bit can be written if not configured as OSC2; otherwise, the bit can not be written and reads as ‘1’