PIC16F720-ESLASHML datasheet(161/244 Pages) MICROCHIP

161 / 244 page

 2010 Microchip Technology Inc.

DS41430A-page 161

PIC16F/LF720/721

18.0

FLASH PROGRAM MEMORY

SELF READ/SELF WRITE

CONTROL

The Flash Program Memory is readable and writable

during normal operation of the device. This memory is

not directly mapped in the register file space. Instead,

it is indirectly addressed through the Special Function

Registers. There are six SFRs used to read/write this

memory:

•PMCON1

•PMCON2

•PMDATL

•PMDATH

• PMADRL

• PMADRH

When interfacing the program memory block, the

PMDATL and PMDATH registers form a two byte word

which holds the 14-bit program data for reading, and

the PMADRL and PMADRH registers form a two byte

word which holds the 13-bit address of the program

Flash location being accessed. These devices have 2K

to 4K words of program memory with an address range

from 0000h to 0FFFh.

Devices without a full map of memory will shadow

accesses to unused blocks back to the implemented

memory.

18.1

Program Memory Read Operation

To read a program memory location, the user must

write two bytes of the address to the PMADRH and

PMADRL

registers,

then

set

control

bit

(PMCON1<0>). Once the read control bit is set, the

Program Memory Read (PMR) controller uses the two

instruction cycles to read the data. This causes the two

instructions immediately following the ‘BSF PMCON1,

RD’ instruction to be ignored.

The data is available in the third cycle, following the set

of the RD bit, in the PMDATH and PMDATL registers.

PMDATL and PMDATH registers will hold this value

until another read is executed. See Example 18-1 and

Figure 18-1 for more information.

EXAMPLE 18-1:

FLASH PROGRAM MEMORY READ

Note:

Interrupts must be disabled during the

time from setting PMCON1<0> (RD) to

the third instruction thereafter.

* This code block will read 1 word of program

* memory at the memory address:

PROG_ADDR_HI: PROG_ADDR_LO

data will be returned in the variables;

PROG_DATA_HI, PROG_DATA_LO

BANKSEL

PMADRL

; Select Bank 2

MOVLW

PROG_ADDR_LO

;

MOVWF

PMADRL

; Store LSB of address

MOVLW

PROG_ADDR_HI

;

MOVWL

PMADRH

; Store MSB of address

BANKSEL

PMCON1

; Select Bank 3

BCF

INTCON,GIE

; Disable interrupts

BSF

PMCON1,RD

; Initiate read

NOP

; Ignored (Figure 18-1)

NOP

; Ignored (Figure 18-1)

BSF

INTCON,GIE

; Restore interrupts

BANKSEL

PMDATL

; Select Bank 2

MOVF

PMDATL,W

; Get LSB of word

MOVWF

PROG_DATA_LO

; Store in user location

MOVF

PMDATH,W

; Get MSB of word

MOVWF

PROG_DATA_HI

; Store in user location

PIC16F720-E/ML датащи(PDF) 161 Page - Microchip Technology

PIC16F720-E/ML датащи(HTML) 161 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

датащи скачать

ссылки URL