PIC10F220 datasheet(22/86 Pages) MICROCHIP

22 / 86 page

PIC10F220/222

DS41270E-page 20

4.9

Indirect Data Addressing; INDF

and FSR Registers

The INDF register is not a physical register. Addressing

INDF actually addresses the register whose address is

contained in the FSR register (FSR is a pointer). This is

indirect addressing.

4.9.1

INDIRECT ADDRESSING

• Register file 09 contains the value 10h

• Register file 0A contains the value 0Ah

• Load the value 09 into the FSR register

• A read of the INDF register will return the value

of 10h

• Increment the value of the FSR register by one

(FSR = 0A)

• A read of the INDR register now will return the

value of 0Ah.

Reading INDF itself indirectly (FSR = 0) will produce

00h. Writing to the INDF register indirectly results in a

no-operation (although Status bits may be affected).

A simple program to clear RAM locations 10h-1Fh

using Indirect addressing is shown in Example 4-1.

EXAMPLE 4-1:

HOW TO CLEAR RAM

USING INDIRECT

ADDRESSING

The FSR is a 5-bit wide register. It is used in conjunc-

tion with the INDF register to indirectly address the data

memory area.

The FSR<4:0> bits are used to select data memory

addresses 00h to 1Fh.

FIGURE 4-6:

DIRECT/INDIRECT ADDRESSING

Note:

Do not use banking. FSR <7:5> are

unimplemented and read as ‘1’s.

MOVLW

0x10

;initialize pointer

MOVWF

FSR

;to RAM

CLRF

INDF

;clear INDF

;register

INCF

FSR,F

;inc pointer

BTFSC

FSR,4

;all done?

GOTO

;NO, clear next

CONTINUE

;YES, continue

Note 1: For register map detail, see Section 4.3 “Data Memory Organization”.

Location Select

Indirect Addressing

Direct Addressing

Data

Memory(1)

0Fh

10h

Bank 0

(FSR)

00h

1Fh

(opcode)

PIC10F220 датащи(PDF) 22 Page - Microchip Technology

PIC10F220 датащи(HTML) 22 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

датащи скачать

ссылки URL