PIC16C926 Microchip Technology Inc., PIC16C926 Datasheet - Page 28

• Manufacturer Part Number: PIC16C926
• Description: 64/68-pin Cmos Microcontrollers With Lcd Driver
• Manufacturer: Microchip Technology Inc.

PIC16C925/926
2.6
The INDF register is not a physical register. Addressing
the INDF register will cause indirect addressing.
Indirect addressing is possible by using the INDF reg-
ister. Any instruction using the INDF register actually
accesses the register pointed to by the File Select Reg-
ister (FSR). Reading the INDF register itself, indirectly
(FSR = ’0’), will produce 00h. Writing to the INDF regis-
ter 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 2-6.
FIGURE 2-6:
DS39544A-page 26
Bank Select
RP1:RP0
Note: For memory map detail, see Figure 2-3.
Indirect Addressing, INDF and
FSR Registers
Direct Addressing
Location Select
6
Data
Memory
DIRECT/INDIRECT ADDRESSING
From Opcode
7Fh
00h
Bank 0
00
0
Bank 1
01
Preliminary
Bank 2
10
A simple program to clear RAM locations 20h-2Fh
using indirect addressing is shown in Example 2-2.
EXAMPLE 2-2:
NEXT
CONTINUE
Bank 3
11
IRP
MOVLW 0x20
MOVWF FSR
CLRF
INCF
BTFSS FSR,4
GOTO
:
Bank Select
00h
7Fh
INDF
FSR,F
NEXT
7
Indirect Addressing
INDIRECT ADDRESSING
2001 Microchip Technology Inc.
;initialize pointer
;to RAM
;clear INDF register
;inc pointer
;all done?
;no clear next
;yes continue
FSR Register
Location Select
0