9
／
30
HTE029A1
6.2.2
MCU Serial Peripheral Interface (3-wire SPI)
The 3-wire serial interface consists of SCLK (serial clock), SDIN (serial data) and CS#. In SPI mode, D0 acts as
SCLK and D1 acts as SDIN. The operation is similar to 4-wire serial interface while D/C# pin is not used. There are
altogether 9-bits will be shifted into the shift register in sequence: D/C# bit, D7 to D0 bit. The D/C# bit (first bit of the
sequential data) will determine the following data byte in the shift register is written to the Display Data RAM (D/C#
bit = 1) or the command register (D/C# bit = 0). Under serial mode, only write operations are allowed.
Table -2 : Control pins of 3-wire Serial Peripheral interface
Function
CS# pin D/C# pin SCLK pin
Write command
L
Tie LOW
↑
Write data
L
Tie LOW
↑
Note:
↑ stands for rising edge of signal
Figure 6-1 : Write procedure in 3-wire Serial Peripheral Interface mode
D0
D1
D2
D3
D4
D5
D6
D7
D/C#
SDIN(D1)
SCLK
DBn
DB2
DB1
CS#
SDIN/
SCLK
