hd66765 Renesas Electronics Corporation., hd66765 Datasheet - Page 20

• Manufacturer Part Number: hd66765
• Description: 396-channel Segment Driver With Internal Ram For 4096-color Displays - Hitachi Semiconductor
• Manufacturer: Renesas Electronics Corporation.

Entry Mode (R05h)
Compare Register (R06h)
The write data sent from the microcomputer is modified in the HD66765 and written to the GRAM. The
display data in the GRAM can be quickly rewritten to reduce the load of the microcomputer software
processing. For details, see the Graphics Operation Function section.
HWM: When HWM=1, data can be written to the GRAM at high speed. In high-speed write mode, four
words of data are written to the GRAM in a single operation after writing to RAM four times. Write to
RAM four times, otherwise the four words cannot be written to the GRAM. Thus, set the lower 2 bits to 0
when setting the RAM address. For details, see High-Speed RAM Write Mode section.
I/D1-0: When I/D1-0 = 1, the address counter (AC) is automatically incremented by 1 after the data is
written to the GRAM. When I/D1-0 = 0, the AC is automatically decremented by 1 after the data is
written to the GRAM. The increment/decrement setting of the address counter by I/D1-0 is done
independently for the upper (AD15-8) and lower (AD7-0) addresses. The direction of moving through the
addresses when the GRAM is written to is set by the AM bit.
AM: Set the automatic update method of the AC after the data is written to the GRAM. When AM = 0,
the data is continuously written in parallel. When AM = 1, the data is continuously written vertically.
When window address range is specified, the GRAM in the window address range can be written to
according to the I/D1-0 and AM settings.
R/W
W
W
RS
1
1
DB15
0
0
DB14
0
0
Figure 8 Entry Mode and Compare Register Instruction
DB13
0
0
DB12
0
0
CP11
DB11
0
CP10
DB10
0
HWM
CP9
DB9
20
CP8
DB8
0
CP7
DB7
0
CP6
DB6
0
CP5
I/D1
DB5
CP4
I/D0
DB4
CP3
AM
DB3
LG2
CP2
DB2
HD66765
LG1
CP1
DB1
LG0
CP0
DB0