Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller PDIP 40 8-Bit 40 MHz I/O number 36

PIC18F2XXX/4XXX FAMILY

DS39622L-page 16  2010 Microchip Technology Inc.

TABLE 3-3: ERASE CODE MEMORY CODE SEQUENCE

FIGURE 3-3: SINGLE ROW ERASE CODE MEMORY FLOW

4-Bit

Command

Data Payload Core Instruction

Step 1: Direct access to code memory and enable writes.

0000

8E A6

9C A6

84 A6

BSF EECON1, EEPGD

BCF EECON1, CFGS

BSF EECON1, WREN

Step 2: Point to first row in code memory.

0000

6A F8

6A F7

6A F6

CLRF TBLPTRU

CLRF TBLPTRH

CLRF TBLPTRL

Step 3: Enable erase and erase single row.

0000

88 A6

82 A6

00 00

BSF EECON1, FREE

BSF EECON1, WR

NOP – hold PGC high for time P9 and low for time P10.

Step 4: Repeat Step 3, with the Address Pointer incremented by 64 until all rows are erased.

Done

Start

Hold PGC Low

for Time P10

All

rows

done?

Yes

Addr = 0

Configure

Device for

Row Erases

Addr = Addr + 64

Start Erase Sequence

and Hold PGC High

for Time P9