PIC16F722A Datasheet, PDF (26/284 Pages) Microchip Technology – 28-Pin Flash Microcontrollers with nanoWatt XLP Technology

PIC16F/LF722A/723A
2.5 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
actually 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 of
the STATUS register, as shown in Figure 2-6.
A simple program to clear RAM location 020h-02Fh
using indirect addressing is shown in Example 2-2.
EXAMPLE 2-2: INDIRECT ADDRESSING
MOVLW020h ;initialize pointer
MOVWFFSR ;to RAM
BANKISEL020h
NEXTCLRFINDF ;clear INDF register
INCFFSR ;inc pointer
BTFSSFSR,4 ;all done?
GOTONEXT ;no clear next
CONTINUE
;yes continue
FIGURE 2-6:
DIRECT/INDIRECT ADDRESSING
Direct Addressing
RP1 RP0 6 From Opcode 0
Indirect Addressing
IRP
7
File Select Register0
Bank Select Location Select
Bank Select
00
01
10
11
00h
180h
Location Select
Data
Memory
Note:
7Fh
Bank 0
Bank 1 Bank 2
1FFh
Bank 3
For memory map detail, refer to Figures 2-3 and 2-4.
DS41417A-page 26
 2010 Microchip Technology Inc.