PIC24FJ128GA Datasheet, PDF (47/232 Pages) Microchip Technology – General Purpose, 16-Bit Flash Microcontrollers

PIC24FJ128GA FAMILY
4.0 FLASH PROGRAM MEMORY
Note:
This data sheet summarizes the features
of this group of PIC24FJ devices. It is not
intended to be a comprehensive reference
source.
The PIC24FJ128GA family of devices contains internal
Flash program memory for storing and executing appli-
cation code. The memory is readable, writable and
erasable during normal operation over the entire VDD
range.
Flash memory can be programmed in two ways:
1. In-Circuit Serial Programming (ICSP)
2. Run-Time Self-Programming (RTSP)
ICSP allows a PIC24FJ128GA family device to be seri-
ally programmed while in the end application circuit.
This is simply done with two lines for Programming
Clock and Programming Data (which are named PGCx
and PGDx, respectively), and three other lines for
power (VDD), ground (VSS) and Master Clear (MCLR).
This allows customers to manufacture boards with
unprogrammed devices and then program the micro-
controller just before shipping the product. This also
allows the most recent firmware or a custom firmware
to be programmed.
RTSP is accomplished using TBLRD (table read) and
TBLWT (table write) instructions. With RTSP, the user
may write program memory data in blocks of 64 instruc-
tions (192 bytes) at a time, and erase program memory
in blocks of 512 instructions (1536 bytes) at a time.
4.1 Table Instructions and Flash
Programming
Regardless of the method used, all programming of
Flash memory is done with the table read and table
write instructions. These allow direct read and write
access to the program memory space from the data
memory while the device is in normal operating mode.
The 24-bit target address in the program memory is
formed using bits<7:0> of the TBLPAG register and the
Effective Address (EA) from a W register specified in
the table instruction, as shown in Figure 4-1.
The TBLRDL and the TBLWTL instructions are used to
read or write to bits<15:0> of program memory.
TBLRDL and TBLWTL can access program memory in
both Word and Byte modes.
The TBLRDH and TBLWTH instructions are used to read
or write to bits<23:16> of program memory. TBLRDH
and TBLWTH can also access program memory in Word
or Byte mode.
FIGURE 4-1:
ADDRESSING FOR TABLE REGISTERS
24 bits
Using
Program 0
Program Counter
0
Counter
Using
Table
Instruction
1/0 TBLPAG Reg
8 bits
Working Reg EA
16 bits
User/Configuration
Space Select
24-bit EA
Byte
Select
© 2006 Microchip Technology Inc.
Preliminary
DS39747C-page 45