dsPIC30F Family Reference Manual
DS70052C-page 5-2 © 2004 Microchip Technology Inc.
5.1 Introduction
This section describes programming techniques for Flash program memory and data EEPROM
memory. The dsPIC30F family of devices contains internal program Flash memory for executing
user code. There are two methods by which the user can program this memory:
1. Run-Time Self Programming (RTSP)
2. In-Circuit Serial Programming™ (ICSP™)
RTSP is performed by the user’s software. ICSP is performed using a serial data connection to
the device and allows much faster programming times than RTSP. RTSP techniques are
described in this chapter. The ICSP protocol is described in the dsPIC30F Programming
Specification document, which may be downloaded from the Microchip web site.
The data EEPROM is mapped into the program memory space. The EEPROM is organized as
16-bit wide memory and the memory size can be up to 2K words (4 Kbytes). The amount of
EEPROM is device dependent. Refer to the device data sheet for further information.
The programming techniques used for the data EEPROM are similar to those used for Flash
program memory RTSP. The key difference between Flash and data EEPROM programming
operations is the amount of data that can be programmed or erased during each program/erase
cycle.
5.2 Table Instruction Operation
The table instructions provide one method of transferring data between the program memory
space and the data memory space of dsPIC30F devices. A summary of the table instructions is
provided here since they are used during programming of the Flash program memory and data
EEPROM. There are four basic table instructions:
• TBLRDL: Table Read Low
• TBLRDH: Table Read High
• TBLWTL: Table Write Low
• TBLWTH: Table Write High
The TBLRDL and the TBLWTL instructions are used to read and write to bits <15:0> of program
memory space. TBLRDL and TBLWTL can access program memory in Word or Byte mode.
The TBLRDH and TBLWTH instructions are used to read or write to bits <23:16> of program
memory space. TBLRDH and TBLWTH can access program memory in Word or Byte mode. Since
the program memory is only 24-bits wide, the TBLRDH and TBLWTH instructions have the ability
to address an upper byte of program memory that does not exist. This byte is called the ‘phantom
byte’. Any read of the phantom byte will return 0x00 and a write to the phantom byte has no
effect.
Always remember that the 24-bit program memory can be regarded as two side-by-side 16-bit
spaces, with each space sharing the same address range. Therefore, the TBLRDL and TBLWTL
instructions access the ‘low’ program memory space (PM<15:0>). The TBLRDH and TBLWTH
instructions access the ‘high’ program memory space (PM<31:16>). Any reads or writes to
PM<31:24> will access the phantom (unimplemented) byte. When any of the table instructions
are used in Byte mode, the LSb of the table address will be used as the byte select bit. The LSb
determines which byte in the high or low program memory space is accessed.
Figure 5-1 shows how the program memory is addressed using the table instructions. A 24-bit
program memory address is formed using bits <7:0> of the TBLPAG register and the effective
address (EA) from a W register, specified in the table instruction. The 24-bit program counter is
shown in Figure 5-1 for reference. The upper 23 bits of the EA are used to select the program
memory location. For the Byte mode table instructions, the LSb of the W register EA is used to
pick which byte of the 16-bit program memory word is addressed. A ‘1’ selects bits <15:8>, a ‘0’
selects bits <7:0>. The LSb of the W register EA is ignored for a table instruction in Word mode.
In addition to the program memory address, the table instruction also specifies a W register (or
a W register pointer to a memory location) that is the source of the program memory data to be
written, or the destination for a program memory read. For a table write operation in Byte mode,
bits <15:8> of the source working register are ignored.
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