PIC12C672 MICROCHIP [Microchip Technology], PIC12C672 Datasheet - Page 18

• Manufacturer Part Number: PIC12C672
• Description: 8-Pin, 8-Bit CMOS Microcontroller with EEPROM Data Memory
• Manufacturer: MICROCHIP [Microchip Technology]

PIC12CE5XX
4.8
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.
EXAMPLE 4-1:
• Register file 07 contains the value 10h
• Register file 08 contains the value 0Ah
• Load the value 07 into the FSR register
• A read of the INDF register will return the value
• Increment the value of the FSR register by one
• A read of the INDR register now will return the
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 4-2.
FIGURE 4-8:
DS40172A-page 18
of 10h
(FSR = 08)
value of 0Ah.
Indirect Data Addressing; INDF and
FSR Registers
bank select
DIRECT/INDIRECT ADDRESSING
(FSR)
6
INDIRECT ADDRESSING
5
Direct Addressing
location select
Note 1: For register map detail see Section 4.2.
Note 2: PIC12CE519 only
Data
Memory
4
(opcode)
(1)
00h
0Fh
10h
0
Preliminary
1Fh
Bank 0
00
3Fh
Bank 1
EXAMPLE 4-2:
NEXT
CONTINUE
The FSR is a 5-bit wide register. It is used in
conjunction 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.
PIC12CE518: Does not use banking. FSR<6:5> are
unimplemented and read as '1's.
PIC12CE519: Uses FSR<5>. Selects between bank 0
and bank 1. FSR<6> is unimplemented, read as '1’ .
Addresses
map back to
addresses
in Bank 0.
01
(2)
movlw
movwf
clrf
incf
btfsc
goto
:
HOW TO CLEAR RAM
USING INDIRECT
ADDRESSING
0x10
FSR
INDF
FSR,F
FSR,4
NEXT
6
Indirect Addressing
1997 Microchip Technology Inc.
bank
5
4
;initialize pointer
; to RAM
;clear INDF register
;inc pointer
;all done?
;NO, clear next
;YES, continue
location select
(FSR)
0