RFPIC12F675K Datasheet, PDF (18/136 Pages) Microchip Technology – 20-Pin FLASH-Based 8-Bit CMOS Microcontroller with UHF ASK/FSK Transmitter

rfPIC12F675
2.4 Indirect Addressing, INDF and
FSR Registers
The INDF register is not a physical register. Addressing
the INDF register will cause indirect addressing.
Indirect addressing is possible by using the INDF
register. Any instruction using the INDF register actu-
ally accesses data pointed to by the File Select register
(FSR). Reading INDF itself indirectly will produce 00h.
Writing to the INDF register indirectly results in a no
operation (although STATUS bits may be affected). An
effective 9-bit address is obtained by concatenating the
8-bit FSR register and the IRP bit (STATUS<7>), as
shown in Figure 2-4.
A simple program to clear RAM location 20h-2Fh using
indirect addressing is shown in Example 2-1.
EXAMPLE 2-1: INDIRECT ADDRESSING
movlw
movwf
NEXT
clrf
incf
btfss
goto
CONTINUE
0x20
FSR
INDF
FSR
FSR,4
NEXT
;initialize pointer
;to RAM
;clear INDF register
;inc pointer
;all done?
;no clear next
;yes continue
FIGURE 2-4:
DIRECT/INDIRECT ADDRESSING rfPIC12F675
Direct Addressing
RP1⁽¹⁾ RP0 6
From Opcode 0
Indirect Addressing
IRP⁽¹⁾
7
FSR Register 0
Bank Select Location Select
00
01
00h
Bank Select
10
11
180h
Location Select
Data
Memory
Not Used
7Fh
Bank 0
Bank 1 Bank 2
1FFh
Bank 3
For memory map detail see Figure 2-2.
Note 1: The RP1 and IRP bits are reserved; always maintain these bits clear.
DS70091A-page 16
Preliminary
 2003 Microchip Technology Inc.