PIC16F628A-I/P Microchip Technology Inc., PIC16F628A-I/P Datasheet - Page 89

• Manufacturer Part Number: PIC16F628A-I/P
• Description: 18 PIN, 3.5 KB FLASH, 224 RAM, 16 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F628A-I/P

• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 128 Bytes
• Input Output: 16
• Interface: USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 18-pin PDIP
• Programmable Memory: 3.5K Bytes
• Ram Size: 224 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

13.0
The EEPROM data memory is readable and writable
during normal operation (full V
is not directly mapped in the register file space. Instead
it is indirectly addressed through the Special Function
Registers (SFRs). There are four SFRs used to read
and write this memory. These registers are:
• EECON1
• EECON2 (Not a physically implemented register)
• EEDATA
• EEADR
EEDATA holds the 8-bit data for read/write, and
EEADR holds the address of the EEPROM location
being accessed. PIC16F62X devices have 128 bytes of
data EEPROM with an address range from 0h to 7Fh.
REGISTER 13-1:
13.1
The EEADR register can address up to a maximum of
256 bytes of data EEPROM. Only the first 128 bytes of
data EEPROM are implemented and only seven of the
eight bits in the register (EEADR<6:0>) are required.
The upper bit is address decoded. This means that this
bit should always be '0' to ensure that the address is in
the 128 byte memory space.
13.2
EECON1 is the control register with five low order bits
physically implemented. The upper-three bits are non-
existent and read as '0's.
Control bits RD and WR initiate read and write,
respectively. These bits cannot be cleared, only set, in
software. They are cleared in hardware at completion
of the read or write operation. The inability to clear the
WR bit in software prevents the accidental, premature
termination of a write operation.
 2003 Microchip Technology Inc.
DATA EEPROM MEMORY
EEADR
EECON1 AND EECON2
REGISTERS
bit 7
bit 6-0
EEADR REGISTER (ADDRESS: 9Bh)
bit 7
Unimplemented Address: Must be set to ‘0’
EEADR: Specifies one of 128 locations of EEPROM Read/Write Operation
Legend:
R = Readable bit
-n = Value at POR
Reserved
R/W
DD
range). This memory
EADR6
R/W
EADR5
R/W
Preliminary
W = Writable bit
’1’ = Bit is set
EADR4
R/W
The EEPROM data memory allows byte read and write.
A byte write automatically erases the location and
writes the new data (erase before write). The EEPROM
data memory is rated for high erase/write cycles. The
write time is controlled by an on-chip timer. The write-
time will vary with voltage and temperature as well as
from chip to chip. Please refer to AC specifications for
exact limits.
When the device is code protected, the CPU may
continue to read and write the data EEPROM memory.
The device programmer can no longer access
this memory.
Additional information on the Data EEPROM is
available in the PICmicro™ Mid-Range Reference
Manual, (DS33023).
The WREN bit, when set, will allow a write operation.
On power-up, the WREN bit is clear. The WRERR bit is
set when a write operation is interrupted by a MCLR
Reset or a WDT Timeout Reset during normal
operation. In these situations, following RESET, the
user can check the WRERR bit and rewrite the
location. The data and address will be unchanged in
the EEDATA and EEADR registers.
Interrupt flag bit EEIF in the PIR1 register is set when
write is complete. This bit must be cleared in software.
EECON2 is not a physical register. Reading EECON2
will read all '0's. The EECON2 register is used
exclusively in the Data EEPROM write sequence.
U = Unimplemented bit, read as ‘0’
’0’ = Bit is cleared
EADR3
R/W
EADR2
R/W
PIC16F62X
x = Bit is unknown
EADR1
R/W
DS40300C-page 87
EADR0
R/W
bit 0