Datasheet
2010-2012 Microchip Technology Inc. DS41419D-page 23
PIC16(L)F1824/1828
3.1.1.2 Indirect Read with FSR
The program memory can be accessed as data by
setting bit 7 of the FSRxH register and reading the
matching INDFx register. The MOVIW instruction will
place the lower eight bits of the addressed word in the
W register. Writes to the program memory cannot be
performed via the INDF registers. Instructions that
access the program memory via the FSR require one
extra instruction cycle to complete. Example 3-2
demonstrates accessing the program memory via an
FSR.
The High directive will set bit<7> if a label points to a
location in program memory.
EXAMPLE 3-2: ACCESSING PROGRAM
MEMORY VIA FSR
3.2 Data Memory Organization
The data memory is partitioned in 32 memory banks
with 128 bytes in a bank. Each bank consists of
(Figure 3-2):
• 12 core registers
• 20 Special Function Registers (SFR)
• Up to 80 bytes of General Purpose RAM (GPR)
• 16 bytes of common RAM
The active bank is selected by writing the bank number
into the Bank Select Register (BSR). Unimplemented
memory will read as ‘0’. All data memory can be
accessed either directly (via instructions that use the
file registers) or indirectly via the two File Select
Registers (FSR). See Section 3.5 “Indirect
Addressing” for more information.
3.2.1 CORE REGISTERS
The core registers contain the registers that directly
affect the basic operation. The core registers occupy
the first 12 addresses of every data memory bank
(addresses x00h/x08h through x0Bh/x8Bh). These
registers are listed in Table 3-2 below. For detailed
information, see Tab le 3- 3.
TABLE 3-2: CORE REGISTERS
constants
RETLW DATA0 ;Index0 data
RETLW DATA1 ;Index1 data
RETLW DATA2
RETLW DATA3
my_function
;… LOTS OF CODE…
MOVLW LOW constants
MOVWF FSR1L
MOVLW HIGH constants
MOVWF FSR1H
MOVIW 0[FSR1]
;THE PROGRAM MEMORY IS IN W
Addresses BANKx
x00h or x80h INDF0
x01h or x81h INDF1
x02h or x82h PCL
x03h or x83h STATUS
x04h or x84h FSR0L
x05h or x85h FSR0H
x06h or x86h FSR1L
x07h or x87h FSR1H
x08h or x88h BSR
x09h or x89h WREG
x0Ah or x8Ah PCLATH
x0Bh or x8Bh INTCON