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15.2
Overview of Flash Memory
15.2.1
Features
The features of the flash memory are summarized below.
• Four flash memory operating modes
Program mode
Erase mode
Program-verify mode
Erase-verify mode
• Programming/erase methods
The flash memory is programmed 32 bytes at a time. Erasing is performed by block erase. The
block to be erased can be specified by setting the corresponding bit. There are block areas of
32 kbytes × 3 blocks, 28 kbytes × 1 block, and 1 kbyte × 4 blocks.
• Programming/erase times
The flash memory programming time is 10 ms (typ.) for simultaneous 32-byte programming,
equivalent to 300 µs (typ.) per byte, and the erase time is 100 ms (typ.) per block.
• Reprogramming capability
The flash memory can be reprogrammed up to 100 times.
• On-board programming modes
There are two modes in which flash memory can be programmed/erased/verified on-board:
Boot mode
User program mode
• Automatic bit rate adjustment
With data transfer in boot mode, the this LSI's bit rate can be automatically adjusted to match
the transfer bit rate of the host (9600 bps and 4800 bps).
• Flash memory emulation by RAM
Part of the RAM area can be overlapped onto flash memory, to emulate flash memory updates
in real time.
• PROM mode
Flash memory can be programmed/erased in PROM mode, using a PROM programmer, as
well as in on-board programming mode.
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