HD66789 Datasheet, PDF (106/156 Pages) Renesas Technology Corp – 528-channel, One-chip Driver for Amorphous TFT Panels with 262,144-color display RAM, Power Supply Circuit, and Gate Circuit

HD66789
Preliminary
Graphics Operation Function
The HD66789 greatly reduces the load on the graphics-processing software in the microcomputer with the
18-bit bus architecture and the graphics bit operation. The graphics bit operation includes:
1. The write data mask function that selectively rewrites some of the 18-bit write data.
2. The conditional rewrite function that compares the write data and the compare bit data and writes
the data sent from the microcomputer only when the conditions are satisfied.
The graphics bit operation is controlled by setting bits in the entry mode register and RAM-write-data mask
register, and the write operation from the microcomputer.
Graphics Operation
Operation Mode
Write mode 1
Write mode 2
Write mode 3
Write mode 4
Bit Setting
I/D AM
0/1 0
0/1 1
0/1 0
0/1 1
LG2–0
000
000
110 111
110 111
Operation and Usage
Horizontal data replacement
Vertical data replacement
Conditional horizontal data replacement
Conditional vertical data replacement
+1/-1 +256
Address
counter
(AC)
16
Microcomputer
18
Write data latch
18
Logical/Compare operation (LG2-0)
000: replacement
110: replacement with matched write
111: replacement with unmatched write
18
Write bit mask
Graphics RAM (GRAM)
3
Logical operation bit
(LG2-0)
18
Compare bit (CP17-0)
18
Write-mask register
(WM17-0)
Graphics operation flow
Rev.0.12, May 09 2003, page 106 of 156