PIC16F1938 Datasheet, PDF (27/452 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers

3.1.1.2 Indirect Read with FSR
The program memory can be accessed as data by set-
ting bit 7 of the FSRxH register and reading the match-
ing INDFx register. The MOVIW instruction will place the
lower 8 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 pro-
gram memory via the FSR require one extra instruction
cycle to complete. Example 3-2 demonstrates access-
ing 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
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
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.
PIC16(L)F1938/9
3.2.1 CORE REGISTERS
The core registers contain the registers that directly
affect the basic operation of the PIC16(L)F1938/9.
These registers are listed below:
• INDF0
• INDF1
• PCL
• STATUS
• FSR0 Low
• FSR0 High
• FSR1 Low
• FSR1 High
• BSR
• WREG
• PCLATH
• INTCON
Note: The core registers are the first 12
addresses of every data memory bank.
 2011 Microchip Technology Inc.
Preliminary
DS41574A-page 27