16F877 A Microcontroller
PERIPHERAL
FEATURES
· Timer0:
8-bit timer/counter with 8-bit prescaler
· Timer1:
16-bit timer/counter with prescaler can be incremented during SLEEP via
external Crystal/clock
· Timer2:
8-bit timer/counter with 8-bit period Register, prescaler and postscaler.
· Two
Capture, Compare, PWM modules
· 10-bit
multi-channel Analog-to-Digital converter
· Synchronous
Serial Port (SSP) with SPI (Master Mode) and I2C (Master/Slave)
· Universal
Synchronous Asynchronous Receiver Transmitter (USART/SCI) with 9-bit address
Detection
· Parallel
Slave Port (PSP) 8-bits wide, with
External RD, WR and CS control (40/44-pin) only
· 2
PWD
· Self
programming
· Parallel
Slave port
PORT
A
PORT A is a 6-bit wide,
bi-directional port. The corresponding data
direction register is TRIS A. Setting a TRIS A bit (= 1) will make the
corresponding PORT A pin an input (i.e., put the corresponding output driver in
a Hi-Impedance mode). Clearing a TRISA bit (= 0) will make the corresponding
PORTA pin an output (i.e., put the contents of the output latch on the selected
pin. A write to a port implies that the port pins are read; the value is
modified and then written to the port data latch.
Port
A functions
Port
B
Port B is an 8-bit wide,
bi-directional port. The corresponding data direction register is TRISB.
Setting a TRISB bit (= 1) will make the corresponding PORT B pin an input
(i.e., put the corresponding output driver in a Hi-Impedance mode). Clearing a
TRIS B bit (= 0) will make the corresponding PORTB pin an output (i.e., put the
contents of the output latch on the selected pin)
Port B functions
PORT
C
PORT
C is an 8-bit wide, bi-directional port. The corresponding data direction
register is TRISC. Setting TRISC bit (= 1) will make the corresponding PORTC
pin an input. Clearing a TRISC bit (= 0) will make the corresponding PORTC pin
an output.
Port C functions
PORT
D
PORT D is
an 8-bit port with Schmitt Trigger input buffers. Each pin is individually
configurable as an input or output
Port D functions
PORT
E
PORT E 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. The PORT E pins become
the I/O control inputs for the microprocessor port when bit PSPMODE
(TRISE<4>) is set. In this mode, the user must make certain that the
TRISE<2:0> bits are set and that the pins are configured as digital
inputs. Also, ensure that 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 for 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.
Port E functions
Port E functions
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