dsPIC33FJ32MC204 Microchip Technology, dsPIC33FJ32MC204 Datasheet - Page 57

• Manufacturer Part Number: dsPIC33FJ32MC204
• Description: (dsPIC33FJ16MC304 / dsPIC33FJ32MC20x) 16-bit Microcontrollers
• Manufacturer: Microchip Technology

4.4.1
Programmers can program one row of program Flash
memory at a time. To do this, it is necessary to erase
the 8-row erase page that contains the desired row.
The general process is:
1.
2.
3.
EXAMPLE 4-1:
© 2007 Microchip Technology Inc.
; Set up NVMCON for block erase operation
; Init pointer to row to be ERASED
Read
(512 instructions) and store in data RAM.
Update the program data in RAM with the
desired new data.
Erase the block (see Example 4-1):
a)
b)
c)
d)
e)
Set the NVMOP bits (NVMCON<3:0>) to
‘0010’ to configure for block erase. Set the
ERASE (NVMCON<6>) and WREN
(NVMCON<14>) bits.
Write the starting address of the page to be
erased into the TBLPAG and W registers.
Write 0x55 to NVMKEY.
Write 0xAA to NVMKEY.
Set the WR bit (NVMCON<15>). The erase
cycle begins and the CPU stalls for the dura-
tion of the erase cycle. When the erase is
done, the WR bit is cleared automatically.
MOV
MOV
MOV
MOV
MOV
TBLWTL W0, [W0]
DISI
MOV
MOV
MOV
MOV
BSET
NOP
NOP
PROGRAMMING ALGORITHM FOR
FLASH PROGRAM MEMORY
eight
#0x4042, W0
W0, NVMCON
#tblpage(PROG_ADDR), W0
W0, TBLPAG
#tbloffset(PROG_ADDR), W0
#5
#0x55, W0
W0, NVMKEY
#0xAA, W1
W1, NVMKEY
NVMCON, #WR
rows
ERASING A PROGRAM MEMORY PAGE
of
program
memory
Preliminary
;
; Initialize NVMCON
;
; Initialize PM Page Boundary SFR
; Initialize in-page EA[15:0] pointer
; Set base address of erase block
; Block all interrupts with priority <7
; for next 5 instructions
; Write the 55 key
;
; Write the AA key
; Start the erase sequence
; Insert two NOPs after the erase
; command is asserted
4.
5.
6.
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
following the start of the programming sequence
should be NOPs, as shown in Example 4-3.
Write the first 64 instructions from data RAM into
the program memory buffers (see Example 4-2).
Write the program block to Flash memory:
a)
b)
c)
d)
Repeat steps 4 and 5, using the next available
64 instructions from the block in data RAM by
incrementing the value in TBLPAG, until all
512 instructions are written back to Flash memory.
Set the NVMOP bits to ‘0001’ to configure
for row programming. Clear the ERASE bit
and set the WREN bit.
Write 0x55 to NVMKEY.
Write 0xAA to NVMKEY.
Set the WR bit. The programming cycle
begins and the CPU stalls for the duration of
the write cycle. When the write to Flash mem-
ory is done, the WR bit is cleared
automatically.
DS70283B-page 55