18F45K80 datasheet(21/52 Pages) MICROCHIP

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 2011 Microchip Technology Inc.

DS39972B-page 21

PIC18FXXK80 FAMILY

3.2

Code Memory Programming

Programming code memory is accomplished by first

loading data into the write buffer and then initiating a

programming sequence. The write and erase buffer

sizes, shown in Table 3-10, can be mapped to any

location of the same size beginning at 000000h. The

actual memory write sequence takes the contents of

this buffer and programs the proper amount of code

memory that contains the Table Pointer.

The programming duration is externally timed and is

controlled by PGC. After a Start Programming

command is issued (4-bit command, ‘1111’), a NOP is

issued, where the 4th PGC is held high for the duration

of the programming time, P9.

After PGC is brought low, the programming sequence

is terminated. PGC must be held low for the time

specified by Parameter P10 to allow high-voltage

discharge of the memory array.

The code sequence to program a PIC18FXXK80 family

device is shown in Table 3-11. The flowchart, shown in

Figure 3-6, depicts the logic necessary to completely

write a PIC18FXXK80 family device. The timing

diagram that details the Start Programming command,

and Parameters P9 and P10 is shown in Figure 3-4.

TABLE 3-10:

WRITE AND ERASE

BUFFER SIZES

FIGURE 3-4:

TABLE WRITE AND START PROGRAMMING INSTRUCTION TIMING (‘1111’)

Note:

The TBLPTR register must point to the

same region when initiating the program-

ming sequence as it did when the write

buffers were loaded.

All Devices

Write Buffer Size

in Bytes

Erase Buffer

Size in Bytes

PIC18FXXK80

15 16

PGC

P5A

PGD

PGD = Input

P9(1)

P10

Programming Time

16-Bit

Data Payload

4-Bit Command

16-Bit Data Payload

4-bit Command

Note 1: Use P9A for User ID and Configuration Word programming.

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