HD66787 Datasheet, PDF (63/159 Pages) Renesas Technology Corp – 528-channel, One-chip Driver with 262,144-color Display RAM and Power Supply Circuit for Low-temperature Poli-Si TFT (LTPS-TFT) Panels with Incorporat

HD66787
Preliminary
Read Data Read from GRAM (R22h)
R/W RS
R1
RAM Read data (RD17-0) The pin assignment for DB17-0 varies for each interface (see below).
RD17–0: Read 18-bit data from GRAM. The bit assignment for the data that are read out from GRAM is
different according to the interface.
When data are read out from GRAM to the microcomputer, the first word read immediately after GRAM
address set are latched in the internal read-data latch, and thereby nullify the data in the data bus (DB17–0).
The second word is read as valid data. When the HD66787 performs an internal bit processing, such as
logical operation, it uses the data latched in the read-data latch. Therefore the processing is completed by
single read out operation. The data are expanded internally into 18 bits before going through the logical
operation. When the 8-/16-bit interfaces are selected, the GRAM data in the LSBs of R and B pixels are
not read out. This function is not available in RGB interface mode.
18-bit interface
GRAM data _{R5 R4 R3 R2 R1 R0 G5 G4 G3 G2 G1 G0 B5 B4 B3 B2 B1 B0}
One pi xel
Read _{RD RD RD RD RD RD RD RD RD RD RD RD RD RD RD RD RD RD}
data _{17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0}
Output DB DB DB DB DB DB DB DB DB DB DB DB DB DB DB DB DB DB
17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Read data from GRAM: Bit assignment
Rev.0.22, May.23.2003, page 63 of 159