HN58S256A Series
3. Software data protetion
To prevent unintentional programming caused by noise generated by external circuits. This device has
the software data protection function. In software data protection mode, 3 bytes of data must be input
before write data as follows. And these bytes can switch the non-protection mode to the protection mode.
SDP is not enabled if only the 3 bytes code is input.
Address
Data
5555
AA
↓
↓
2AAA
55
↓
↓
5555
A0
↓
↓
Write address Write data } Normal data input
Software data protection mode can be cancelled by inputting the following 6 bytes. After that, this device
turns to the non-protection mode and can write data normally. But when the data is input in the
cancelling cycle, the data cannot be written.
Address
5555
↓
2AAA
↓
5555
↓
5555
↓
2AAA
↓
5555
Data
AA
↓
55
↓
80
↓
AA
↓
55
↓
20
The software data protection is not enabled at the shipment.
Note: There are some differences between Hitachi’s and other company’s for enable/disable sequence
of software data protection. If there are any questions , please contact with Hitachi sales offices.