PIC18F2455-I/SP Microchip Technology Inc., PIC18F2455-I/SP Datasheet - Page 80

• Manufacturer Part Number: PIC18F2455-I/SP
• Description: Microcontroller; 24 KB Flash; 2048 RAM; 256 EEPROM; 24 I/O; 28-Pin-SPDIP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F2455-I/SP

• A/d Inputs: 10-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 12 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 23
• Interface: I2C/SPI/USART/USB
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 24K Bytes
• Ram Size: 2K Bytes
• Speed: 48 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC18F2450/4450
6.4
The minimum erase block is 32 words or 64 bytes. Only
through the use of an external programmer, or through
ICSP control, can larger blocks of program memory be
Bulk Erased. Word Erase in the Flash array is not
supported.
When
microcontroller itself, a block of 64 bytes of program
memory is erased. The Most Significant 16 bits of the
TBLPTR<21:6> point to the block being erased.
TBLPTR<5:0> are ignored.
The EECON1 register commands the erase operation.
The WREN bit must be set to enable write operations.
The FREE bit is set to select an erase operation.
For protection, the write initiate sequence for EECON2
must be used.
A long write is necessary for erasing the internal Flash.
Instruction execution is halted while in a long write
cycle. The long write will be terminated by the internal
programming timer.
EXAMPLE 6-2:
DS39760A-page 78
Required
Sequence
initiating
Erasing Flash Program Memory
ERASE_ROW
an
ERASING A FLASH PROGRAM MEMORY ROW
erase
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BCF
BSF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BSF
sequence
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
EECON1, CFGS
EECON1, WREN
EECON1, FREE
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
INTCON, GIE
Advance Information
from
the
; load TBLPTR with the base
; address of the memory block
; access Flash program memory
; enable write to memory
; enable Row Erase operation
; disable interrupts
; write 55h
; write 0AAh
; start erase (CPU stall)
; re-enable interrupts
6.4.1
The sequence of events for erasing a block of internal
program memory is:
1.
2.
3.
4.
5.
6.
7.
8.
Load Table Pointer register with address of row
being erased.
Set the EECON1 register for the erase operation:
• clear the CFGS bit to access program memory;
• set WREN bit to enable writes;
• set FREE bit to enable the erase.
Disable interrupts.
Write 55h to EECON2.
Write 0AAh to EECON2.
Set the WR bit. This will begin the Row Erase
cycle.
The CPU will stall for duration of the erase
(about 2 ms using internal timer).
Re-enable interrupts.
FLASH PROGRAM MEMORY
ERASE SEQUENCE
© 2006 Microchip Technology Inc.