VRS51L1050
IAP Flash Control Register
The VRS51L1050 IAP function operation is controlled
by the IAP Flash control register, IAPFCTRL. Setting
the IAPSTART bit to 1 starts the execution of the IAP
command specified by the IAPFCT[1:0] bits of the IAP
Flash control register.
T
ABLE
10:IAP F
LASH
C
ONTROL
R
EGISTER
- SFR F7
H
IAP Byte Program Function
The IAP byte program function is used to program a
byte into a specified Flash memory location under the
control of the IAP feature (see the following program
example):
IAP_PROG: MOV
MOV
MOV
MOV
MOV
MOV
MOV
MOV
IAPFDATA,#55H
IAPFDATA,#0AAH
IAPFDATA,#55H
SYSCON,#04H
IAPFADHI, FADRSH
IAPFADLO,FADRSL
IAPFDATA,FDATA
IAPFCTRL,#80H
;Sequence to Enable Writing
; the IAPSTART bit
;ENABLE IAP FUNCTION
;Set MSB of address to program
;Set LSB of address to program
;Set Data to Program
;Set the IAP Start bit
7
6
5
4
3
2
IAPFCTRL[15:8]
1
0
Bit
7
6
5
4
3
2
1
0
Mnemonic
IAPSTART
Unused
Unused
Unused
Unused
Unused
IAPFCT[1:0]
Description
IAP Selected operation start sequence
-
-
-
-
-
Flash Memory IAP Function
;**The program Counter will stop until the IAP function is completed
IAP Page Erase Function
Using the IAP feature, it is possible to perform a page
erase of the VRS51L1050 Flash memory (the memory
area occupied by the ISP boot program cannot be
page erased). Each page is 512 bytes in size.
To perform a Flash page erase, the page address is
specified by the XY (hex) value written into the
IAPFADHI register. (The value 00h must be written
into the IAPFADLO registers.)
If the “Y” portion of the IAPFADHI register represents
an even number, the page to be erased corresponds
to the range XY00h to X(Y+1)FFh.
If the “Y” portion of the IAPFADHI register represents
an odd number, the page to be erased corresponds to
the range X(Y-1)00h to XYFFh.
The following program example erases the page
corresponding to the address B000h-CFFFh:
;** Erase Flash page located at address B000h to CFFFh.
PageErase: MOV
IAPFDATA,#55H
;Sequence to Enable Writing
MOV
IAPFDATA,#0AAH
; the IAPSTART bit
MOV
IAPFDATA,#55H
MOV
MOV
MOV
MOV
SYSCON,#04H
IAPFADHI, #0B0h
IAPFADLO,#00h
IAPFCTRL,#82H
;ENABLE IAP FUNCTION
;Set MSB of Page address to erase
;Set LSB of address = 00
;SET THE IAP START BIT
The IAP subsystem handles four different functions.
Which are controlled by the IAPFCT bits as follows:
T
ABLE
11:IAP F
UNCTIONS
IAPFCT[1:0] Bits value
00
01
10
11
IAP Function
Flash Byte Program
Flash Erase Protect
Flash Page Erase
Flash Erase
It is important to note that for security reasons, the
IAPSTART bit of the IAPFCTRL register is configured
as read-only by default.
To set the IAPSTART bit to 1, the following operation
sequence must be performed:
MOV
MOV
MOV
IAPFDATA,#55h
IAPFDATA,#AAh
IAPFDATA,#55h
Once the start bit is set to 1, the IAP subsystem will
read the contents of the IAP Flash address and data
registers and hold the VRS51L1050 program counter
at its current value until the IAP operation is complete.
When it is complete, the IAPSTART bit will be cleared
and the program will continue executing.
IAP Chip Erase & Chip Protect Functions
The IAP chip erase function will erase the entire Flash
memory contents, with the exception of the ISP boot
program area. Running this function will also
automatically unprotect the Flash memory.
When the chip protect function is enabled, values read
back from Flash memory will be 00h.
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