PIC16F870_13 Datasheet, PDF (39/172 Pages) Microchip Technology – 28/40-Pin, 8-Bit CMOS FLASH Microcontrollers

4.5 PORTE and TRISE Register
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.
Note: On a Power-on Reset, these pins are
configured as analog inputs.
PIC16F870/871
FIGURE 4-7:
PORTE BLOCK DIAGRAM
(IN I/O PORT MODE)
Data
Bus
DQ
WR
PORT
CK
I/O pin⁽¹⁾
Data Latch
WR
TRIS
DQ
CK
TRIS Latch
Schmitt
Trigger
input
buffer
RD PORT
RD TRIS
Q
D
EN
Note 1: I/O pins have protection diodes to VDD and VSS.
 2000-2013 Microchip Technology Inc.
DS30569C-page 39