HD6433044 Datasheet, PDF(599/867 Page) Hitachi Semiconductor – Hitachi Single-Chip Microcomputer

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HD6433044 Datasheet, PDF (599/867 Pages) Hitachi Semiconductor – Hitachi Single-Chip Microcomputer

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18.7.1 Program Mode

To write data into the flash memory, follow the programming algorithm shown in figure 18-15.

This programming algorithm can write data without subjecting the device to voltage stress or

impairing the reliability of programmed data.

To program data, first set the VPPE bit in FLMCR, wait 5 to 10 Âµs, then designate the blocks to be

programmed by erase block registers 1 and 2 (EBR1, EBR2), and write the data to the address to

be programmed, as in writing to RAM. The flash memory latches the address and data in an

address latch and data latch. Next set the P bit in FLMCR, selecting program mode. The

programming duration is the time during which the P bit is set. A software timer should be used to

provide an initial programming duration of 15.8 Âµs or less. Programming for too long a time, due

to program runaway for example, can cause device damage. Before selecting program mode, set

up the watchdog timer so as to prevent overprogramming.

18.7.2 Program-Verify Mode

In program-verify mode, after data has been programmed in program mode, the data is read to

check that it has been programmed correctly.

After the programming time has elapsed, exit programming mode (clear the P bit to 0) and select

program-verify mode (set the PV bit to 1). In program-verify mode, a program-verify voltage is

applied to the memory cells at the latched address. If the flash memory is read in this state, the

data at the latched address will be read. After selecting program-verify mode, wait 4 Âµs before

reading, then compare the programmed data with the verify data. If they agree, exit program-

verify mode and program the next address. If they do not agree, select program mode again and

repeat the same program and program-verify sequence. Do not repeat the program and program-

verify sequence more than 6 times for the same bit. (When a bit is programmed repeatedly, set a

loop counter so that the total programming time will not exceed 1 ms.)

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