Microchip Technology dsPIC30F - Program Memory Writes

dsPIC30F Family Reference Manual
DS70051C-page 4-10 © 2004 Microchip Technology Inc.
4.4.3 PSV Timing
Instructions that use PSV will require two extra instruction cycles to complete execution, except
the following instructions that require only one extra cycle to complete execution:
-The MAC class of instructions with data pre-fetch operands
-All MOV instructions including the MOV.D instruction
The additional instruction cycles are used to fetch the PSV data on the program memory bus.
4.4.3.1
Using PSV in a Repeat Loop
Instructions that use PSV within a REPEAT loop eliminate the extra instruction cycle(s) required
for the data access from program memory, hence incurring no overhead in execution time.
However, the following iterations of the REPEAT loop will incur an overhead of two instruction
cycles to complete execution:
- The first iteration
- The last iteration
- Instruction execution prior to exiting the loop due to an interrupt
- Instruction execution upon re-entering the loop after an interrupt is serviced
4.4.3.2
PSV and Instruction Stalls
Refer to Section 2. “CPU” for more information about instruction stalls using PSV.
4.5 Program Memory Writes
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 accomplished using TBLWT instructions. ICSP is accomplished using the SPI interface
and integral bootloader software. Refer to Section 5. “Flash and EEPROM Programming” for
further details about RTSP. ICSP specifications can be downloaded from the Microchip
Technology web site (www.microchip.com).