PIC18F23K22 datasheet(12/42 Pages) MICROCHIP

12 / 42 page

PIC18(L)F2XK22/4XK22

DS41398B-page 12

Advance Information

 2010 Microchip Technology Inc.

2.7

Serial Program/Verify Operation

The PGC pin is used as a clock input pin and the PGD

pin is used for entering command bits and data input/

output during serial operation. Commands and data are

transmitted on the rising edge of PGC, latched on the

falling edge of PGC and are Least Significant bit (LSb)

first.

2.7.1

4-BIT COMMANDS

All instructions are 20 bits, consisting of a leading 4-bit

command followed by a 16-bit operand, which depends

on the type of command being executed. To input a

command, PGC is cycled four times. The commands

needed for programming and verification are shown in

Table 2-6.

Depending on the 4-bit command, the 16-bit operand

represents 16 bits of input data or 8 bits of input data

and 8 bits of output data.

Throughout this specification, commands and data are

presented as illustrated in Table 2-7. The 4-bit

command is shown Most Significant bit (MSb) first. The

command operand, or “Data Payload”, is shown

<MSB><LSB>. Figure 2-16 demonstrates how to

serially present a 20-bit command/operand to the

device.

2.7.2

CORE INSTRUCTION

The core instruction passes a 16-bit instruction to the

CPU core for execution. This is needed to set up

registers as appropriate for use with other commands.

TABLE 2-6:

COMMANDS FOR

PROGRAMMING

TABLE 2-7:

SAMPLE COMMAND

SEQUENCE

FIGURE 2-16:

TABLE WRITE, POST-INCREMENT TIMING DIAGRAM (1101)

Description

4-Bit

Command

Core Instruction

(Shift in16-bit instruction)

0000

Shift out TABLAT register

0010

Table Read

1000

Table Read, post-increment

1001

Table Read, post-decrement

1010

Table Read, pre-increment

1011

Table Write

1100

Table Write, post-increment by 2

1101

Table Write, start programming,

post-increment by 2

1110

Table Write, start programming

1111

4-Bit

Command

Data

Payload

Core Instruction

1101

3C 40

Table Write,

post-increment by 2

PGC

PGD

PGD = Input

234

P5A

10 11

Fetch Next 4-bit Command

P2A

4-bit Command

16-bit Data Payload

P2B

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