PIC17C756A MICROCHIP [Microchip Technology], PIC17C756A Datasheet - Page 89

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

10.8
PORTH is an 8-bit wide, bi-directional port. The corre-
sponding data direction register is DDRH. A ’1’ in
DDRH configures the corresponding port pin as an
input. A ’0’ in the DDRH register configures the corre-
sponding port pin as an output. Reading PORTH reads
the status of the pins, whereas writing to PORTH will
write to the respective port latch.
The upper four bits of PORTH are multiplexed with
4 channels of the 10-bit A/D converter.
The remaining bits of PORTH are general purpose I/O.
Upon RESET, RH7:RH4 are automatically configured
as analog inputs and must be configured in software to
be a digital I/O.
FIGURE 10-17:
2000 Microchip Technology Inc.
WR PORTH
WR DDRH
RD PORT
PCFG3:PCFG0
V
CHS3:CHS0
Note: I/O pins have protection diodes to V
Data Bus
AIN
PORTH and DDRH Registers
(PIC17C76X only)
BLOCK DIAGRAM OF RH7:RH4
Data Latch
DDRH Latch
D
CK
D
CK
RD DDRH
Q
Q
Q
Q
DD
and V
SS
Q
.
To other pads
To other pads
EN
EN
D
EXAMPLE 10-8:
MOVLB
MOVLW
MOVPF
CLRF
MOVLW
MOVWF
8
0x0E
ADCON1
PORTH, F
0x03
DDRH
V
V
P
N
DD
SS
INITIALIZING PORTH
PIC17C7XX
; Select Bank 8
; Configure PORTH as
; digital
; Initialize PORTH data
;
;
;
; Value used to init
;
; Set RH<1:0> as inputs
;
latches before
the data direction
register
data direction
RH<7:2> as outputs
ST
Input
Buffer
DS30289B-page 89
I/O pin