hd66765 Renesas Electronics Corporation., hd66765 Datasheet - Page 9

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

Block Function Description
System Interface
The HD66765 has five high-speed system interfaces: an 80-system 16-bit/8-bit bus, a 68-system 16-bit/8-
bit bus, and a serial peripheral (SPI: Serial Peripheral Interface port). The interface mode is selected by
the IM2-0 pins.
The HD66765 has three 16-bit registers: an index register (IR), a write data register (WDR), and a read
data register (RDR). The IR stores index information from the control registers and the GRAM. The
WDR temporarily stores data to be written into control registers and the GRAM, and the RDR
temporarily stores data read from the GRAM. Data written into the GRAM from the MPU is first written
into the WDR and then is automatically written into the GRAM by internal operation. Data is read
through the RDR when reading from the GRAM, and the first read data is invalid and the second and the
following data are normal. When a logic operation is performed inside of the HD66765 by using the
display data set in the GRAM and the data written from the MPU, the data read through the RDR is used.
Accordingly, the MPU does not need to read data twice nor to fetch the read data into the MPU. This
enables high-speed processing.
Execution time for instruction excluding oscillation start is 0 clock cycle and instructions can be written
in succession.
Table 2
80-system Bus
WR
0
1
0
1
Table 3
Start bytes
R/W Bits
0
1
0
1
RD
1
0
1
0
RS Bits
0
0
1
1
Register Selection (8/16 Parallel Interface)
Register Selection (Serial Peripheral Interface)
Operations
Writes indexes into IR
Reads internal status
Writes into control registers and GRAM through WDR
Reads from GRAM through RDR
68-system
Bus
R/W
0
1
0
1
RS
0
0
1
1
Operations
Writes indexes into IR
Reads internal status
Writes into control registers and GRAM through WDR
Reads from GRAM through RDR
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HD66765