Microchip Technology MA330031-2 Data Sheet

DS70000657H-page 120

 2011-2013 Microchip Technology Inc.

RTSP allows the user application to erase a single
page of memory and to program two instruction words
at a time. See the General Purpose and Motor Control
Family tables

 and 

, respectively) for the

page sizes of each device.
For more information on erasing and programming
Flash memory, refer to “Flash Programming”
(DS70609) in the “dsPIC33/PIC24 Family Reference
Manual”

.

A complete programming sequence is necessary for
programming or erasing the internal Flash in RTSP
mode. The processor stalls (waits) until the programming
operation is finished.
For erase and program times, refer to Parameters

and 

 (Page Erase Time), and 

 and

 (Word Write Cycle Time) in 

 in

Setting the WR bit (NVMCON<15>) starts the opera-
tion and the WR bit is automatically cleared when the
operation is finished.

5.3.1

PROGRAMMING ALGORITHM FOR 
FLASH PROGRAM MEMORY

Programmers can program two adjacent words
(24 bits x 2) of program Flash memory at a time on
every other word address boundary (0x000002,
0x000006, 0x00000A, etc.). To do this, it is necessary
to erase the page that contains the desired address of
the location the user wants to change.
For protection against accidental operations, the write
initiate sequence for NVMKEY must be used to allow
any erase or program operation to proceed. After the
programming command has been executed, the user
application must wait for the programming time until
programming is complete. The two instructions follow-
ing the start of the programming sequence should be
NOP

s.

Refer to Flash Programming” (DS70609) in the
“dsPIC33/PIC24 Family Reference Manual” for details
and codes examples on programming using RTSP.

Many useful resources are provided on the main prod-
uct page of the Microchip web site for the devices listed
in this data sheet. This product page, which can be
accessed using this 

, contains the latest updates

and additional information.

5.4.1

KEY RESOURCES

• “Flash Programming” (DS70609) in the 

• Code Samples
• Application Notes
• Software Libraries
• Webinars
• All Related “dsPIC33/PIC24 Family Reference 

 Sections

• Development Tools

Four SFRs are used to erase and write the program
Flash memory: NVMCON, NVMKEY, NVMADRH and
NVMADRL.
The NVMCON register (

) enables and

initiates Flash memory erase and write operations.
NVMKEY (

) is a write-only register that is

used for write protection. To start a programming or
erase sequence, the user application must
consecutively write 0x55 and 0xAA to the NVMKEY
register.
There are two NVM Address registers: NVMADRH and
NVMADRL. These two registers, when concatenated,
form the 24-bit Effective Address (EA) of the selected
word for programming operations or the selected page
for erase operations.
The NVMADRH register is used to hold the upper 8 bits
of the EA, while the NVMADRL register is used to hold
the lower 16 bits of the EA.

In the event you are not able to access the
product page using the link above, enter
this URL in your browser: