MIPI to HDMI Converter
MIPI high-speed display interface, commonly used in smartphones, tablets, laptops, automobiles, and other platforms. MIPI DSI can transmit large amounts of data, and MIPI interface displays can have high resolution, good color rendering, and can be used for high-speed applications such as video transmission. Manufacturers can use this interface to combine screens to achieve high performance, low power consumption (lower interface level (200mV)), low electromagnetic interference (EMI), and lower pin count than other interfaces.
Different from LVDS and RGB interfaces, there are many types of MIPI interface displays. In fact, almost every display using the MIPI interface is different. The MIPI display needs to be initialized, that is, instructions need to be sent to set the parameters of the driver IC before the display can work. The initialization code of each MIPI display is different, so separate debugging is required when driving a MIPI display.
MIPI DSI Cable Design Advice
Since mipi is a high-speed transmission interface, the length of the MIPI cable usually does not exceed 30cm, and there are many requirements for the design to ensure stable transmission and anti-interference:
1. Impedance matching of signal paths on PCB or FPC
2. Impedance control (100±10% ohm) for HiSSI differential pair (from Tx to Rx)
3. Place the GND layer below the HiSSI signal layer
4. It is recommended to plate a silver layer above HiSSI to shield or GND layer to lower EMI (including FPC bending area)
5. Minimum differential signal crossovers. Cross signals must remain at 90 degrees if required
6. Each HiSSI signal trace has the same width and the trace edge shape is smooth
7. Keep it as straight as possible from system board to FPC to driver IC
8. Separate signal pair and GND (width >30mil), need to be reliably grounded
9. Keep differential pair to GND clearance >2W to reduce crosstalk
10. HiSSI differential pair without through holes
11. Clock and data signal lengths must match to minimize skew
12. Avoid creating stubs on differential signals
13. Keep differential pair ITO resistance as same/low as possible (<10 ohms), e.g. using multiple pins/pads
Imagine you are an embedded (software) engineer and have never touched the MIPI DSI interface. Then driving a MIPI interface with a touch screen display will be a headache. First of all, there are very few learning materials for MIPI DSI. Only after joining the MIPI Alliance can we have complete materials. However, this is not necessary for ordinary developers. Furthermore, MIPI DSI has different interfaces, different connector models, and the number of pins. The arrangements are different, and corresponding adapter cables need to be customized for normal connection. What’s more important is that the correct configuration of the initialization code is required to drive the display normally. If you want to adjust the parameters of the display, you need to find the SPEC of the driver IC and find the correct register to modify it, but there are many functions that you cannot Found it because the manufacturer of the driver IC was not open.
Driving a capacitive touch screen requires more cooperation from the supplier. Unless you are using a touch screen with a USB interface, the touch screen requires multiple adjustments to continuously optimize the touch accuracy and finally complete the firmware adjustment.
If you are developing a new product, our suggestion is to use an MIPI to HDMI converter, or MIPI to LVDS converter, so that you can quickly complete the development process, saving you time and energy and quickly realize your design.
mipi to hdmi converter
Here is an introduction to Fengxiao Technology’s mipi to hdmi converter:
The MIPI to HDMI Converter is mainly used for the receiving part in video/image transmission, decoding high-speed serial LVDS signals into CSI/DSI data to complete the data decoding function. This board can convert HDMI signals to MIPI data output. This MIPI to HDMI coveter is an industrial-grade design with wide temperature parameters, operating temperature: -35 ℃ ~ +80 ℃, MIPI signal supports 2-line/4-line data per lane The transmission rate can reach 1.5Gbps, and the highest resolution supports 1920x1200_60HZ. The low-power chip solution is far smaller than other MIPI solutions on the market and generates very little heat.
MIPI to HDMI converter parameters
display screen interface
640×480～1920×1200, equal resolution LCD
Input signal type
Supports input signal formats
Refer to Appendix A
range of working temperature
Working humidity range
Storage temperature range
Storage humidity range
Working environment atmospheric pressure range
Appendix A:MIPI to HDMI converter supported resolutions
Field frequency [Hz]
Line frequency [kHz]
FAQ about MIPI to HDMI converter
1 Possible fault links Generally, when the display system is abnormal, it is necessary to judge the following links. By checking step by step, the problem can usually be determined. Controller (such as jumpers, PC signal settings); Display (consider controller, signal cables, connections, display, PC signal settings); Backlight (relevant controllers, cables, backlight tubes); Line Cable (such as HDMI cable); Microcomputer system (display settings such as refresh rate, etc.);
2.No display If the connection is incorrect, or there is no power supply (such as no power input, the power switch is not turned on), or the signal output by the PC is not within the adaptive range of this controller, it may cause no display.
3.Image position If the image display position cannot be adjusted appropriately through the OSD, it may be that the output timing of the graphics card does not meet the standard and the controller cannot adapt. You may wish to replace other graphics cards for testing. In addition, some video splitters may also have an impact.
4.Abnormal image display Abnormal display may include missing lines, jitter, flickering, shadows, etc. If the refresh frequency, resolution setting, and scanning method of the graphics card do not match the requirements of the controller, it may cause abnormal image display size, image scrolling, flickering, or even no display. The quality of the cable connecting the display can also cause display abnormalities. The quality of the signal cable directly affects the quality of the input signal and the anti-interference ability of the input terminal. If there is a shadow in the image display, it is likely to be caused by poor quality of the signal cable. If there is no appropriate distance between the backlight and the display signal cable, it may affect the horizontal synchronization signal of the LCD screen, and the impact can be directly seen in the display.
5.Backlight If the backlight is abnormal, you need to check the following aspects: power input, input switch signal, input adjustment (the adjustment signal is not within the required range of the inverter, which may also be the reason why the backlight does not light up) and backlight tube, etc.
6.Other faults Improper use, such as inappropriate input power, circuit short circuit caused by misoperation, incorrect cables, etc. may bring unpredictable adverse consequences.