ST7735SV datasheet(44/201 Pages) SITRONIX

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ST7735SV

V 1.3

Page 44 of 201

2020-01

9.4 Serial Interface

The selection of this interface is done by IM2. See the Table 12.

IM2

4WSPI

Interface

Read Back Selection

3-line Serial Interface

Via the Read Instruction (8-bit, 24-bit and 32-bit Read Parameter)

4-line Serial Interface

Via the Read Instruction (8-bit, 24-bit and 32-bit Read Parameter)

Table 12 Selection of Serial Interface

The serial interface is either 3-lines/9-bits or 4-lines/8-bts bi-directional interface for communication between

the micro controller and the LCD driver. The 3-lines serial interface use: CSX (chip enable), SCL (serial clock)

and SDA (serial data input/output), and the 4-lines serial interface use: CSX (chip enable), D/CX (data/

command flag), SCL (serial clock) and SDA (serial data input/output). Serial clock (SCL) is used for interface

with MCU only, so it can be stopped when no communication is necessary.

9.4.1 Command Write Mode

The write mode of the interface means the micro controller writes commands and data to the LCD driver.

3-lines serial data packet contains a control bit D/CX and a transmission byte. In 4-lines serial interface, data

packet contains just transmission byte and control bit D/CX is transferred by the D/CX pin. If D/CX is “low”,

the transmission byte is interpreted as a command byte. If D/CX is “high”, the transmission byte is stored in

the display data RAM (memory write command), or command register as parameter.

Any instruction can be sent in any order to the driver. The MSB is transmitted first. The serial interface is

initialized when CSX is high. In this state, SCL clock pulse or SDA data have no effect. A falling edge on CSX

enables the serial interface and indicates the start of data transmission.

Figure 16 Serial Interface Data Stream Format

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