UPD161623 datasheet(22/83 Pages) NEC

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Data Sheet S15817EJ2V0DS

µµµµPD161623

5.2.4 Arbitrary address area access (window access mode (WAS))

With the

µPD161623, any area of the display RAM selected by the MIN.·X/Y address registers (R8 and R10) and

MAX.

⋅ X/Y address registers (R9 and R11) can be accessed.

When WAS of data access control register (R5) is set to 1, the window access mode is then selected and accessed

by setting only address area of the MIN.

⋅X/Y address registers and MAX.·X/Y address registers.

. The address scanning setting is also valid in this mode, in the same manner as when data is normally written to the

display RAM. In addition, data can be written from any address by specifying the X address register (R6) and Y

address register (R7).

Note that the display RAM must be accessed after setting the X address register (R6) and Y address register (R7) if

the window access area has been set or changed by the MIN.

⋅ X/Y address register or MAX.⋅ X/Y address register.

Figure 5

−−−−10. Example of Incrementing Address when in Window Access Mode

Start point

End point

EFH

00H

AFH

00H

MIN. X address

MIN. Y address

MAX. Y address

MAX. X address

Cautions 1. When using the window access mode, the relationship between the start point and end point

shown in the table below must be established.

Item

Address Relationship

X address

00H

≤ MIN.⋅X address ≤ X address (R6) ≤ MAX.⋅X address ≤ AFH

Y address

00H

≤ MIN.⋅Y address ≤ Y address (R7) ≤ MAX.⋅Y address ≤ EFH

2. If invalid address data is set as the MIN./MAX.

⋅⋅⋅⋅ address, operation is not guaranteed.

3. Do not specify any value other than the address value 2n

−−−−2 (n = 1 to 88) for the X address in the

high-speed RAM access mode. The operation is not guaranteed if invalid address data is set.

4. Access the display RAM after setting the X address register (R6) and Y address register (R7) if the

window access area has been set or changed by the MIN.

⋅⋅⋅⋅ X/Y address register or MAX.⋅⋅⋅⋅ X/Y

address register.

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