PIC12CE67 Microchip Technology, PIC12CE67 Datasheet - Page 23

• Manufacturer Part Number: PIC12CE67
• Description: 8-Pin/ 8-Bit CMOS Microcontroller with A/D Converter and EEPROM Data Memory
• Manufacturer: Microchip Technology

4.5
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 read 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 4-11. However, IRP
is not used in the PIC12CE67X.
A simple program to clear RAM locations 20h-2Fh
using indirect addressing is shown in Example 4-1.
FIGURE 4-11: DIRECT/INDIRECT ADDRESSING
(1)
1998 Microchip Technology Inc.
bank select
RP1 RP0
For register file map detail see Figure 4-2.
Note 1: The RP1 and IRP bits are reserved, always maintain these bits clear.
Indirect Addressing, INDF and FSR
Registers
location select
6
Direct Addressing
Data
Memory
from opcode
7Fh
00h
Bank 0
00
0
Bank 1
01
Preliminary
Bank 2
10
not used
EXAMPLE 4-1:
NEXT
CONTINUE
Bank 3
11
movlw
movwf
clrf
incf
btfss
goto
:
IRP
bank select
180h
1FFh
(1)
0x20
FSR
INDF
FSR,F
FSR,4
NEXT
INDIRECT ADDRESSING
7
PIC12CE67X
Indirect Addressing
;initialize pointer
;to RAM
;clear INDF register
;inc pointer
;all done?
;no clear next
;yes continue
FSR register
DS40181B-page 23
location select
0