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MB91360G Series
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(3) Write/Erase Modes
The flash memory can be accessed in two different ways; the flash memory mode allowing write/erase directly
from the external pins, and the other modes allowing write/erase from the CPU via the internal bus. These modes
are selected by the external mode pins.
a
:
Flash Memory mode
The CPU stops when the mode pins are set to 111 while the INIT signal is asserted. The flash memory interface
circuit is directly connected to the external bus interface, allowing direct control by the external pins. This mode
makes the MCU seem like a standard flash memory at the external pins, and write/erase can be performed
using a flash memory programmer.
In the flash memory mode all the operations supported by the flash memory automatic algorithm can be used.
b
:
Other modes
The flash memory is located in the CS1 area of the CPU memory space and like ordinary mask ROM can be
read-accessed and program-accessed from the CPU through the flash memory interface circuit. After execution
of the internal Boot ROM the area for CS1 is set from 180000 to FFFFF (F361GA only) .
Writing/erasing the flash memory is performed by instructions from the CPU via the flash memory interface
circuit. Therefore, this mode allows rewriting even when the MCU is soldered on the target board.
The sector protect operations can not be performed in these modes.
c
:
Control signals of flash memory
Next table lists the flash memory control signals in the flash memory mode.
There is almost a one-to-one correspondence between the flash memory control signals and the external pins
of the MBM29LV400C. The V
ID
(12 V) pins required by the sector protect operations are MD0, MD1 and MD2
instead of A9, RESET and OE for the MBM29LV400C.
In the flash memory mode, the width of the external data bus can be 8 or 16 bit.