Rainbow Electronics MAXQ7670 - Manual (Page 27)

MAXQ7670
Microcontroller with 10-Bit ADC,
PGA, 64KB Flash, and CAN Interface
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application code to store data when context switching
(e.g., during a call or an interrupt). Storing and retriev-
ing data is executed through the PUSH, POP, and POPI
instructions.
The incorporation of flash memory allows device repro-
gramming, eliminating the expense of discarding one-
time programmable devices during development and
field upgrades (see Figure 13 for the flash memory sec-
tor maps).
A 16-word key protects the flash memory from access
by unauthorized individuals. Without supplying the 16-
word key, the password lock (PWL) bit in the SC regis-
ter remains set, and the utility ROM is inaccessible.
Supplying the 16-word key makes the utility ROM trans-
parent. The password-unlock command is issued
through the TAP interface. The 16-word password is
compared to the password in the program space to
determine its validity.
Enabling a pseudo-Von Neumann memory map places
the utility ROM, code, and data memory into a single
contiguous memory map. Use this mapping scheme for
applications that require dynamic program modification
or unique memory configurations.
EXECUTING
FROM
PROGRAM
SPACE
DATA SPACE
(WORD MODE)
1024 x 16
DATA RAM
4K x 16
UTILITY ROM
32K x 16
PROGRAM
FLASH
FFFFh
A3FFh
7FFFh
0000h
A400h
A000h
8FFFh
8000h
8FFFh
8000h
03FFh
0000h
FFFFh
7FFFh
0400h
9000h
DATA SPACE
(BYTE MODE)
8K x 8
UTILITY ROM
2048 x 8
DATA RAM
FFFFh
7FFFh
0400h
03FFh
0000h
9000h
8FFFh
8000h
1024 x 16
DATA RAM
4K x 16
UTILITY ROM
Figure 12. MAXQ7670 Memory Map
32K x 16
PROGRAM
FLASH
7FFFh
0000h
1 PAGE = 256 WORDS
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Figure 13. Flash Memory Sector Maps