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Hardware of the PIC16F628

On these pages, I will explain the hardware specification of PICF628. The contents of the explanation is the part which is different from PIC16F873. So, as for the basic specification, refer to PIC16F84A and PIC16F873. As for the detail specification, refer to PIC16F628.
PIC16F628 is PIC which has a lot of features than PIC16F84A. Those functions are the function which is adopted in PIC16F873. The program memory is 2K Words, the RAM memory is 224 bytes and the EEPROM is 128 bytes. It has three kinds of timers, Analog Digital converter, Universal communication port and so on. Also, it has one set of CCP.
Flash memory is used for PIC16F628 like PIC16F84A and PIC16F873. So, the program can be easily rewritten by the PIC programmer. This is very convenient. The instructions of the software are same as PIC16F84A and PIC16F873. The number of the pins is 18 pins like 84A.

RA0-7 : Input/Output port A
RB0-7 : Input/Output port B
AN0-3 : Analog input port
RX : USART Asynchronous Receive
TX : USART Asynchronous Transmit
DT : Synchronous Data
CK : Synchronous Clock
CCP1 : Capture In/Compare Out/PWM Out
OSC1/CLKIN : Oscillator In/Ecternal Clock In
OSC2/CLKOUT : Oscillator Out/Clock Out
MCLR : Master Clear ( Active low Reset )
Vpp : Programming voltage input
T0CKI : Clock input to Timer0
T1OSO : Timer1 oscillator output
T1OSI :Timer1 oscillator input
PGD : Serial programming data
PGC : Serial programming clock
PGM : Low voltage programinng input
INT : External interrupt
VDD : Positive supply for logic and I/O pins
Vss : Ground reference for logic and I/O pins

SFR (Special Function Registers)

Configuration Word

I/O Port

Timer (Same as PIC16F873)
CCP (Same as PIC16F873)

Analog to Digital Converter

Asynchronous mode (USART)
(Same as PIC16F873)


Main difference between 84A and 628 and 873
Program memory1K words2K words4K words
GPR memory 68 bytes
from 0Ch
224 bytes
from 20h
192 bytes
from 20h
I/O port 13 ports
RA : 5
RB : 8
16 ports
RA : 8
RB : 8
RA5 is input only
22 ports
RA : 6
RB : 8
RC : 8
Built-in OSC-4MHz-

Difference with PIC16F84A *GPR is from 20h.
*The contents of configuration word are different.
*RA0-3 are analog port at a default.
*A built-in oscillator can be used.
Difference with PIC16F873 *RA5 os input mode only.
*The contents of PIR1/PIE1 are different.
*The contents of configuration word are different.
*RA0-3 are analog port at a default.
*A built-in oscillator can be used.