Datasheet

© 2007 Microchip Technology Inc. Preliminary DS70165E-page 77
dsPIC33F
4.0 FLASH PROGRAM MEMORY
The dsPIC33F devices contain internal Flash program
memory for storing and executing application code.
The memory is readable, writable and erasable during
normal operation over the entire V
DD range.
Flash memory can be programmed in two ways:
1. In-Circuit Serial Programming™ (ICSP™)
programming capability
2. Run-Time Self-Programming (RTSP)
ICSP allows a dsPIC33F device to be serially
programmed while in the end application circuit. This is
simply done with two lines for programming clock and
programming data (one of the alternate programming
pin pairs: PGC1/PGD1, PGC2/PGD2 or PGC3/PGD3),
and three other lines for power (V
DD), ground (VSS) and
Master Clear (MCLR
). This allows customers to manu-
facture boards with unprogrammed devices and then
program the digital signal 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
can write program memory data either in blocks or
‘rows’ of 64 instructions (192 bytes) at a time or a single
program memory word, and erase program memory in
blocks or ‘pages’ 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
Note: This data sheet summarizes the features
of this group of dsPIC33F devices. It is not
intended to be a comprehensive reference
source. To complement the information in
this data sheet, refer to the “dsPIC30F
Family Reference Manual” (DS70046).
0 Program Counter
24 bits
Program Counter
TBLPAG Reg
8 bits
Working Reg EA
16 bits
Byte
24-bit EA
0
1/0
Select
Using
Table Instruction
Using
User/Configuration
Space Select