PIC16F870_13 Datasheet, PDF (38/172 Pages) Microchip Technology – 28/40-Pin, 8-Bit CMOS FLASH Microcontrollers

PIC16F870/871
4.4 PORTD and TRISD Registers
This section is not applicable to the PIC16F870.
PORTD is an 8-bit port with Schmitt Trigger input buff-
ers. Each pin is individually configurable as an input or
output.
PORTD can be configured as an 8-bit wide micropro-
cessor port (parallel slave port) by setting control bit
PSPMODE (TRISE<4>). In this mode, the input buffers
are TTL.
FIGURE 4-6:
PORTD BLOCK DIAGRAM
(IN I/O PORT MODE)
Data
Bus
WR
Port
D
Q
CK
Data Latch
I/O pin⁽¹⁾
WR
TRIS
DQ
CK
TRIS Latch
Schmitt
Trigger
Input
Buffer
RD TRIS
Q
D
RD Port
ENEN
Note 1: I/O pins have protection diodes to VDD and VSS.
TABLE 4-7: PORTD FUNCTIONS
Name
Bit#
Buffer Type
Function
RD0/PSP0
bit0
ST/TTL⁽¹⁾
Input/output port pin or parallel slave port bit0.
RD1/PSP1
bit1
ST/TTL⁽¹⁾
Input/output port pin or parallel slave port bit1.
RD2/PSP2
bit2
ST/TTL⁽¹⁾
Input/output port pin or parallel slave port bit2.
RD3/PSP3
bit3
ST/TTL⁽¹⁾
Input/output port pin or parallel slave port bit3.
RD4/PSP4
bit4
ST/TTL⁽¹⁾
Input/output port pin or parallel slave port bit4.
RD5/PSP5
bit5
ST/TTL⁽¹⁾
Input/output port pin or parallel slave port bit5.
RD6/PSP6
bit6
ST/TTL⁽¹⁾
Input/output port pin or parallel slave port bit6.
RD7/PSP7
bit7
ST/TTL⁽¹⁾
Input/output port pin or parallel slave port bit7.
Legend: ST = Schmitt Trigger input, TTL = TTL input
Note 1: Input buffers are Schmitt Triggers when in I/O mode and TTL buffers when in Parallel Slave Port mode.
TABLE 4-8: SUMMARY OF REGISTERS ASSOCIATED WITH PORTD
Address Name Bit 7 Bit 6 Bit 5
Bit 4
Bit 3 Bit 2
Bit 1
Bit 0
Value on:
POR, BOR
Value on
all other
RESETS
08h
PORTD RD7 RD6 RD5
RD4
RD3 RD2
RD1
RD0 xxxx xxxx uuuu uuuu
88h
TRISD PORTD Data Direction Register
1111 1111 1111 1111
89h
TRISE
IBF OBF IBOV PSPMODE — PORTE Data Direction Bits
0000 -111 0000 -111
Legend: x = unknown, u = unchanged, - = unimplemented read as '0'. Shaded cells are not used by PORTD.
DS30569C-page 38
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