Design of automobile instrument based on RA8889 liquid crystal display of STM32F103
Table of contents
introduction
At present, the update and iteration of car dashboard forms is getting faster and faster, and colorful dashboards occupy a large market. Traditional mechanical dashboards can no longer meet the needs of car owners. Compared with mechanical dashboards, liquid crystal display dashboards, It has the effects of rich colors, high brightness, multiple functions, and excellent display effects. In this paper, the RA8889 control display IC designed by Taiwan Ruiyou Company is used to develop a car dashboard designed for mainstream small and medium-sized LCD screens (such as common 7-inch and 12.3-inch LCD screens) in the market. The chip has a built-in Media decoder unit (multimedia decoding unit) ), JPEG/BMP decoding, support PNG display, built-in 128Mbit SDRAM, support BTE (graphics acceleration engine), support display effects such as fade in and fade out, and the maximum resolution can support 1366*2048 @24bpp. Using this scheme design, it has the advantages of simple research and development, low cost, powerful functions, etc., high reliability, and belongs to industrial-grade chips. Because the processing of the display part is handled by the RA8889, the MCU is only responsible for issuing instructions.
Overall System Design
The RA8889 is controlled by the MCU as the main control terminal, which can be controlled through the parallel port (8080, 6800), serial port (3/4-SPI, IIC) communication mode, and the MCU is just a simple instruction to the RA8889, and all the displayed content is handed over to the RA8889 deal with. The basic system framework is as follows:
For example, if a picture needs to be displayed on the dashboard, the MCU only needs to issue an instruction to the RA8889 to inform that the picture needs to be displayed, and the subsequent display operations are all processed by the RA8889: the RA8889 reads the picture or video in the FLASH hung on the RA8889 , read it and write it to the video memory, and then display it on the LCD screen of the car. RA8889 supports 24bit RGB output, built-in ASCII Font, geometric graphics engine, supports two-way PWM adjustment, and can realize stepless adjustment of screen brightness. Support four-way SPI Master interface, can be connected to four FLASH at the same time, can also be combined with FLASH+Chinese character library.
System Hardware Design
1.1 Peripheral circuit of RA8889 The peripheral circuit of
RA8889 is relatively simple, only need to match crystal oscillator circuit and capacitor resistor
; 12.3-inch screen with a resolution of 1920*720; it has the characteristics of bright color display, high brightness, and stability. The dual-channel LVDS interface is used, and the RGB signal output by RA8889 can be driven by RGB to dual-channel LVDS conversion IC . The voltage IC can output four LED voltages, which can meet the needs of the screen backlight. The backlight reference circuit is as follows:
total
Overall, the circuit of the LCD instrument panel is relatively simple, which can greatly reduce the development time.
The hardware part is introduced here first, and the software part is predicted, so stay tuned for the next article: software code based on STM32F103 + RA8889 + 12.3-inch screen.
Display renderings and video effects of automotive instrumentation.
picture:
RA8889 TFT Controller Car Dashboard
car dashboard display