With the rapid development of digital technology, the emergence of a variety of digital display also went out there led, LCD, DLP, etc., all kinds of large-screen digital control system diverse, useful ARM + FPGA line control system, but also useful for PC + DVI Interface line decoder chip + FPGA chip control system, where we not only can be used to control about a full-color LED large screen display, but also can be used as the transmitter output high definition image data.
Online control system with full-color LED large-screen control. The PC + DVI + FPGA chip decoder chip interface, glue stick output interface mode + online control system.
DVI Interface Overview.
DVI full name DigitalVisualInterface, which is based on TMDS (TransitionMinimizedDifferentialSignaling, transition minimized differential signaling) protocol as the basic electrical electronic connections. glue gun TMDS is a differential signaling mechanisms, pixel data can be encoded and passed through a serial connection. Graphics generated by the transmitter digital signal encoded in accordance with an agreement by TMDS TMDS channel sent to the receiver, decoded to give digital display devices.
DVI interface, the current is divided into two, one DVI-D interface, can only receive digital signals, the interface is only 3 rows of eight pins 24, which is empty right corner of a pin, not compatible with analog signals.
The other is DVI-I interface, compatible with both analog and digital signals. Fortunately, that does not mean compatible with analog analog D-Sub interface can be connected to the DVI-I interface, but must be used through an adapter, generally will use this interface with the related graphics adapter.
This paper describes the interface used is the DVI-D full-data interface.
FPGA control system, full-color LED large-screen principle.
1DVI decoder chip control principle.
Figure 3 shows the input part of the FPGA chip to control the decoder chip control schematic diagram, the selected FPGA chip is Xilinx's Spantan_3 series X3C1400A-5, the chip can achieve the maximum clock of 200MHz DDR_SDRAM control. In the system used DVI decoder chip produced by TI, the chip model tfp401 decoder chip that received by the computer through the DVI interface transfer to the encoded image data, output to DVI decoder chip, the chip serial data decoded into 24 bits of R (Red), G (Green), B (Blue) RGB parallel data, and the horizontal sync, vertical sync, data enable and clock signals, and then decoded RGB image data, line synchronization, vertical sync, data enable and clock control signals are sent to FPGA chip, the image data to the FPGA chip FIFO buffer, where it should be noted that the resolution of the image when the collection is large, the data transfer clock signal can reach 165MHz, the output image data for the 24-bit parallel data, so the maximum bandwidth of up to 3.96GHz, the selected external memory bandwidth requirements are to be considered.
4 applied to different areas of the two output modes.
① FPGA chip output terminal drive current chips.
The interface is used for the output drive current multi-chip FPGA chip output pins with multiple external timing control IC drive current, drive current on the chip and then to control RGB light emitting diodes, and finally the image you want to display the entire computer LED display on the big screen.
② receiver for the Ethernet line interface.
The interface is suitable for one input DVI output of the image decoding chip interface, the interface can be used for long distance transmission of image information, applied to large screen LED display.
Advantages of using DVI interface to the display device.
DVI is a digital signal transmission, digital image information without going through any conversion, will be directly transferred to the display device, and then to reduce the number of digital to analog conversion process cumbersome, saving the time, so it's faster , can effectively eliminate the phenomenon of smear, the use of DVI data transmission, the signal does not decay, the color is more pure, more realistic. Transmission inside the computer is a binary digital signal, using the VGA interface displays full-color LED large screen, you need cards in the first signal through D / A converter into R, G, B primary color signals and horizontal and vertical sync signal, these signals through the analog signal line transferred to the full-color LED big screen, you also need the corresponding A / D converter analog signals into digital signals once again to the full-color LED display images on the big screen. In the above D / A, A / D conversion and signal transmission process and the inevitable loss of signal interference, resulting in image distortion or error. DVI interfaces without the need for these conversions, to avoid signal loss, so that image clarity and detail of expression have been greatly improved.
Conclusion.
The design of the FPGA chip control system to achieve full-color large screen image display system, not only for small size resolution (256 × 192) full-color LED control system for large-screen display, but also long-distance Ethernet transmission image data, image data is sent to the receiver template multi-block, multi-block receiver board can be used to display resolution mosaic (1920 × 1280) high-definition color images of the big screen.