PIC16F871 Microchip Technology Inc., PIC16F871 Datasheet - Page 41

• Manufacturer Part Number: PIC16F871
• Description: 28/40-pin, 8-bit Cmos Flash Microcontrollers
• Manufacturer: Microchip Technology Inc.

4.5
This section is not applicable to the PIC16F870.
PORTE has three pins, RE0/RD/AN5, RE1/WR/AN6
and RE2/CS/AN7, which are individually configurable
as inputs or outputs. These pins have Schmitt Trigger
input buffers.
I/O PORTE becomes control inputs for the micropro-
cessor port when bit PSPMODE (TRISE<4>) is set. In
this mode, the user must make sure that the
TRISE<2:0> bits are set (pins are configured as digital
inputs). Ensure ADCON1 is configured for digital I/O. In
this mode, the input buffers are TTL.
Register 4-1 shows the TRISE register, which also
controls the parallel slave port operation.
PORTE pins are multiplexed with analog inputs. When
selected as an analog input, these pins will read as '0's.
TRISE controls the direction of the RE pins, even when
they are being used as analog inputs. The user must
make sure to keep the pins configured as inputs when
using them as analog inputs.
 2003 Microchip Technology Inc.
Note:
PORTE and TRISE Register
On a Power-on Reset, these pins are
configured as analog inputs.
FIGURE 4-7:
Note 1: I/O pins have protection diodes to V
Data
Bus
WR
TRIS
WR
PORT
RD PORT
TRIS Latch
Data Latch
D
D
PIC16F870/871
CK
CK
RD TRIS
Q
Q
PORTE BLOCK DIAGRAM
(IN I/O PORT MODE)
Q
EN
Schmitt
Trigger
input
buffer
D
DS30569B-page 39
DD
and V
I/O pin
SS
.
(1)