Kingtech has been specializing in TFT LCD module since 2003 and our mainly products are TFT LCD module, LCD screen with touch such as resistive touch and capacitive touch, E-paper, Mono display, OLED, LCD with board etc.
For the OLED, TFT LCD module and LCD with HMI board products, there are two modes: Serial and Parallel interface.
Serial interface is also COM interface. It is an extension interface that uses serial communication method. The characteristic is that the communication line is simple, and only one pair of transmission lines can achieve bidirectional communication, greatly reducing costs. It is particularly suitable for long-distance communication, but the transmission speed is slowly, the distance is from a few meters to several kilometers.
Serial interface is classified according to electrical standards and protocols including RS-232-C, RS-422, RS485 etc.
Parallel interface is also Centronics interface (IEEE1284). The interface uses parallel transmission to transmit data. From the simplest parallel data register or dedicated interface integrated circuit chips such as 8255, 6820, to more complex SCSI or IDE parallel interfaces, there are dozens of types.
The parallel interface characteristics have two:
- The width of a data channel transmitted in parallel, also known as the number of bits transmitted through an interface;
- Characteristics of additional interface control lines or interactive signals used to coordinate parallel data transmission. The width of the data can range from 1 to 128 bits or wider, with the most common used being 8 bits, which can be transmitted 8 data bits at a time through an interface, so the commonly used parallel interface is LPT. In addition, the characteristic of parallel interface is high speed, close distance and many lines.
The communication principles is that the all data of parallel interface is transmitted in parallel, it’s usually in units of bytes (8 bits) or bytes (16 bits).
SPI interface mode:
2.1 SPI interface composition:
(1) Control signals:/CS (IC enable select signal), D/C (command or Data selection, SCL (serial clock signal)
(2) Data signal: SDI or SDA (serial data input signal)
SDO (Serial Data Output Signal)
2.2 SPI interface application:
TFT needs to use SPI interface, one condition is that the IC must have GRAM, and
One external condition is that the serial port speed of the IC must be fast enough to support TFT screens.
Screen refresh rate, so SPI interface is generally used for 240RGBx320 or below small-sized TFT.
2.3 SPI interface classification:
The SPI interface is divided into 3-line and 4-line SPI interfaces. 3-line, 4-line.
The difference is that the 4-line SPI interface has D/C control signals, while the 3-line SPI interface
No D/C control signal.
3-line Serial parallel interface: 4-line serial parallel interface:
Serial and parallel interface difference:
The serial interface can be described as a lane, while a parallel interface has 8 lanes that can transmit 8 bits (one byte) of data at the same time. However, it does not mean that the parallel interface is fast. Because of the mutual interference (crosstalk) between 8-bit channels and the transmission speed has limited, and it’s easy errors during transmission. The serial interface does not interference with each other. The amount of data sent simultaneously through parallel interface is large, but the speed is slower than serial interface.
