PIC18LF4331-ESLASHML datasheet(91/392 Pages) MICROCHIP

91 / 392 page

 2010 Microchip Technology Inc.

DS39616D-page 91

PIC18F2331/2431/4331/4431

8.5

Writing to Flash Program Memory

The programming block size is 4 words or 8 bytes.

Word or byte programming is not supported.

Table writes are used internally to load the holding

registers needed to program the Flash memory. There

are 8 holding registers used by the table writes for

programming.

Since the Table Latch (TABLAT) is only a single byte,

the TBLWT instruction has to be executed 8 times for

each programming operation. All of the table write

operations will essentially be short writes, because only

the holding registers are written. At the end of updating

8 registers, the EECON1 register must be written to, to

start the programming operation with a long write.

The long write is necessary for programming the

internal Flash. Instruction execution is halted while in a

long write cycle. The long write will be terminated by

the internal programming timer.

The EEPROM on-chip timer controls the write time.

The write/erase voltages are generated by an on-chip

charge pump, rated to operate over the voltage range

of the device.

FIGURE 8-5:

TABLE WRITES TO FLASH PROGRAM MEMORY

Note:

The default value of the holding registers

on device Resets and after write operations

is FFh. A write of FFh to a holding register

does not modify that byte. This means that

individual bytes of program memory may

be modified, provided that the modification

does not attempt to change any bit from a

‘0’ to a ‘1’. When modifying individual

bytes, it is not necessary to load all 64 hold-

ing registers before executing a write

operation.

Holding Register

TABLAT

Holding Register

TBLPTR = xxxxx7

Holding Register

TBLPTR = xxxxx1

Holding Register

TBLPTR = xxxxx0

Write Register

TBLPTR = xxxxx2

Program Memory

PIC18LF4331-E/ML Datasheet(PDF) 91 Page - Microchip Technology

PIC18LF4331-E/ML Datasheet(HTML) 91 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL