MCU Serial Interface (4-wire SPI)

The 4-wire serial interface consists of

serial clock: SCLK,

serial data: SDIN, D/C#, CS#. In 4-wire SPI mode,

D0 acts as SCLK, D1 acts as SDIN.

For the unused data pins, D2 should be left open.

The pins from D3 to D7, E and R/W# (WR#)# can be connected to an external


SDIN is shifted into an 8-bit shift register on every rising edge of SCLK in
the order of D7, D6, ... D0.

D/C# is sampled on every eighth clock and the data byte in the shift register
is written to the Graphic Display Data RAM (GDDRAM) or command register in the
same clock.
Under serial mode, only write operations are allowed.