HD64646FS datasheet(32/50 Pages) HITACHI

32 / 50 page

HD64645/64646

Internal Registers

The HD64645/HD64646 has one address register and fourteen data registers. In order to select one out of

fourteen data registers, the address of the data register to be selected must be written into the address

To be software compatible with the CRTC (HD6845), registers R2–R8, R16, and R17, which are not

necessary for an LCD are defined as invalid for the LCTC.

Address Register (AR)

AR register (Figure 22) specifies one out of 14 data registers. Address data is written into the address

invalid.

Horizontal Total Characters Register (R0)

R0 register (Figure 23) specifies a horizontal scanning period. The total number of horizontal characters

less 1 must be programmed into this 8-bit register in character units. Nht indicates the horizontal scanning

period including the period when the CPU occupies memory (total number of horizontal characters minus

the number of horizontal displayed characters). Its units are, then, converted from time into the number of

characters. This value should be specified according to the specification of the LCD system to be used.

Note the following restrictions

Nhd +

≤ Nht + 1

Mode No.

5, 9

1, 6, 7, 8, 10, 11, 12, 13

2, 3, 4

Horizontal Displayed Characters Register (R1)

R1 register (Figure 24) specifies the number of characters displayed per row. The horizontal character

pitches are 8 bits for normal character display and 16 dots for wide character display and graphic display.

Nhd must be less than the total number of horizontal characters.

HD64646FS Datasheet(PDF) 32 Page - Hitachi Semiconductor