HD6433640 HITACHI [Hitachi Semiconductor], HD6433640 Datasheet - Page 158

• Manufacturer Part Number: HD6433640
• Description: H8/3644 Series Hardware Manual
• Manufacturer: HITACHI [Hitachi Semiconductor]

6.7.7
Prewrite-verify mode is a verify mode used to all bits to equalize their threshold voltages before
erasure.
To program all bits, write H'00 in accordance with the prewrite algorithm shown in figure 6.16.
Use this procedure to set all data in the flash memory to H'00 after programming. After the
necessary programming time has elapsed, exit program mode (by clearing the P bit to 0) and select
prewrite-verify mode (leave the P, E, PV, and EV bits all cleared to 0). In prewrite-verify mode, a
prewrite-verify voltage is applied to the memory cells at the read address. If the flash memory is
read in this state, the data at the read address will be read. After selecting prewrite-verify mode,
wait at least 4 s before reading.
Note: For a sample prewriting program, see the prewrite subroutine in the sample erasing
6.7.8
There are two modes for flash memory program/erase protection: hardware protection and
software protection. These two protection modes are described below.
Software Protection: With software protection, setting the P or E bit in the flash memory control
register (FLMCR) does not cause a transition to program mode or erase mode.
Details of software protection are given below.
Item
Block
protect
Note: * Three modes: program-verify, erase-verify, and prewrite-verify.
program.
Prewrite-Verify Mode
Protect Modes
Description
Programming and erase protection can be
set for individual blocks by settings in the
erase block registers (EBR1 and EBR2).
Setting EBR1 to H'F0 and EBR2 to H'00
places all blocks in the program/erase-
protected state.
Program
Disabled
Erase
Disabled
Functions
Verify*
Enabled
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