Datasheet

PIC16F785/HV785
DS41249E-page 22 © 2008 Microchip Technology Inc.
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
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 and the IRP bit in the
STATUS Register, 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
FIGURE 2-4: DIRECT/INDIRECT ADDRESSING PIC16F785/HV785
MOVLW 0x20 ;initialize pointer
MOVWF FSR ;to RAM
NEXT CLRF INDF ;clear INDF register
INCF FSR ;increment pointer
BTFSS FSR,4 ;all done?
GOTO NEXT ;no clear next
CONTINUE ;yes continue
Note: For memory map detail see Figure 2-2.
Data
Memory
Indirect AddressingDirect Addressing
Bank Select Location Select
RP1
RP0
6
0
From Opcode
IRP
File Select Register
7
0
Bank Select
Location Select
00 01 10 11
180h
1FFh
00H
7FH
Bank 0 Bank 1 Bank 2 Bank 3