PIC18FXXK80 Datasheet, PDF(32/52 Page) Microchip Technology – Flash Microcontroller Programming Specification

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PIC18FXXK80 Datasheet, PDF (32/52 Pages) Microchip Technology – Flash Microcontroller Programming Specification

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PIC18FXXK80 FAMILY

4.3 Verify Configuration Bits

A configuration address may be read and output on

PGD via the 4-bit command, â1001â. Configuration data

is read and written in a byte-wise fashion, so it is not

necessary to merge two bytes into a word prior to a

compare. The result may then be immediately

compared to the appropriate configuration data in the

programmerâs memory for verification. Refer to

Section 4.1 âRead Code Memory, ID Locations and

Configuration Bitsâ for implementation details of

reading configuration data.

4.4 Read Data EEPROM Memory

Data EEPROM is accessed, one byte at a time, via an

Address Pointer (register pair, EEADRH:EEADR) and

a Data Latch (EEDATA). Data EEPROM is read by

loading EEADRH:EEADR with the desired memory

location and initiating a memory read by appropriately

configuring the EECON1 register (Register 3-1). The

data will be loaded into EEDATA, where it may be

serially output on PGD via the 4-bit command, â0010â

(Shift Out Data Holding register). A delay of P6 must be

introduced after the falling edge of the 8th PGC of the

operand to allow PGD to transition from an input to an

output. During this time, PGC must be held low (see

Figure 4-4).

The command sequence to read a single byte of data

is shown in Table 4-2.

FIGURE 4-3:

READ DATA EEPROM

FLOW

Start

Set

Address

Read

Byte

Move to TABLAT

Shift Out Data

Done?

Yes

Done

TABLE 4-2: READ DATA EEPROM MEMORY

4-Bit

Command

Data Payload

Core Instruction

Step 1: Direct access to data EEPROM.

0000

9E 7F

9C 7F

BCF EECON1, EEPGD

BCF EECON1, CFGS

Step 2: Set the data EEPROM Address Pointer.

0000

0E <Addr>

6E 74

OE <AddrH>

6E 75

MOVLW

MOVWF

MOVLW

MOVWF

<Addr>

EEADR

<AddrH>

EEADRH

Step 3: Initiate a memory read.

0000

80 7F

BSF EECON1, RD

Step 4: Load data into the Serial Data Holding register.

0000

0010

50 73

6E F5

00 00

MOVF EEDATA, W, 0

MOVWF TABLAT

NOP

Shift Out Data(1)

Note 1: The <LSB> is undefined; the <MSB> is the data.

DS39972B-page 32

ï£ 2011 Microchip Technology Inc.

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