MCU and design solutions for car LCD TV/display

The car LCD TV/ 显示器\'); companyAdEvent.show(this,\'companyAdDiv\',[5,18])"> display market is developing rapidly, and users expect manufacturers to provide low-cost, fully functional products. Engineers need to design simple, convenient, and flexible overall solutions. This article introduces the features of the SP633 MCU for car LCD TVs/displays and the matching single-chip TV decoder M61260FP/M61266FP, as well as application examples, design methods, and precautions.

China's automobile industry is in a period of rapid development, especially the development of household cars is more rapid, and the market demand for in-vehicle color LCD monitors/TVs is gradually increasing. However, there has been no dedicated in-vehicle color LCD monitor/TV product control chip on the market. Except for a few companies with the strength to develop MCU, most equipment manufacturers use MCUs used for color TVs as control chips for color LCD monitors/TV products. Its shortcomings are: 1. This type of MCU is designed for CRT TVs, and many special requirements for in-vehicle and LCD TVs cannot be met; 2. Most of these chips are DIP packages, which are large in size, while in-vehicle monitors/TVs are generally 4-7 inches, so the smaller the driver chip, the better.

Figure 1: Block diagram of Jinyi's LCD TV/monitor solution

SP633 is a multifunctional MCU control chip (with mask already made) specially developed for small-sized in-vehicle or portable LCD monitors/TVs. The design block diagram of a small-sized LCD TV based on SP633 is shown in Figure 1. The main chip is the MCU SP633 and the single-chip TV decoder M61260FP/M61266FP.

SP633 has three I/O control ports: 16:9/4:3 control and image up/down/left/right control. If the LCD screen does not have corresponding control pins or the product design does not require these functions, they can be used to control other functions. For example, when making a car ceiling display, any I/O pin can be used as a remote control switch for the roof light.

Regarding the interface design of M61260/M61266 and various LCD screens, it should be noted that the decoded output of M61260/M61266 is the three primary color signals of R, G, B and the horizontal and vertical synchronization signals. A gamma correction circuit needs to be added later, and the optional related chips are such as M52338 and IR3Y26. Finally, a timing control (commonly known as T-CON) chip needs to be added . Different analog screens have different T-CON ICs.

As shown in Figure 1, SP633 is designed to be used with M61260FP/M61266FP through I2C bus connection, which can basically realize a ready-made LCD TV solution without even debugging. M61260FP and M61266FP are fully pin-compatible. Generally, M61266FP (PAL/NTSC) can be used. If SECAM standard is required, just change M61266FP to M61260FP without changing the circuit board. The TV decoder can realize two AV inputs - M61260FP: AV1, AV2 (multiplexed with S terminal), M61264FP: AV1 (multiplexed with S terminal), YUV input. [page]

This solution has the functions of an ordinary monitor and realizes general TV functions, such as 256 (0-255) channel storage, one PWM volume output control; image parameter adjustment: contrast, brightness, chroma, clarity and hue (NTSC); sound parameter adjustment (volume); rearrangement function; image format selection - M61260: automatic, PAL, NTSC, NTSC443, SECAM, M61264: automatic, PAL, NTSC, NTSC443; automatic/manual channel search function; AFC automatic adjustment function; mute function; program exchange function, etc.

In addition, this solution also has the following special features.

1. Support audio FM modulator control: convenient for car use, users can enjoy high-quality sound effects (using FM radio to wirelessly receive TV audio) without changing the car audio. When not watching TV, other audio sources, such as VCD/DVD/MP3, can also be input into the FM modulator and listened to with the car audio.

2. Supports automatic control of the car's rear-view camera when the driver is reversing: When the driver is reversing, no matter what state the LCD TV is in, it will automatically switch to AV2, connect to the car's rear-view camera, and monitor the reversing status; when the reversing operation is completed, the LCD TV will automatically return to the previous state TV or AV1.

3. 16:9/4:3 image mode conversion control.

Figure 2: SP633 and its peripheral control circuit diagram in LCD TV solution

4. Image up/down, left/right flip control.

5. Full-function remote control: The remote control IC uses SAA3010 and compatible low-cost IC.

6. Support additional channel (cable TV) reception: expand the scope of use and increase the number of receiving channels.

7. The OSD screen characters are enlarged to facilitate user viewing.

The single-chip TV decoder M61260 has built-in VIF VC coils (34.47, 38, 38.9, 39.5 and 45.75MHz), built-in audio notch filters and bandpass filters (4.5, 5.5, 6.0, 6.5, 5.74MHz); built-in chroma filter and brightness delay line, baseband 1H chroma delay line (for NTSC); uses digital AFT; built-in automatic synchronization separation circuit, vertical AGC circuit (for M61266FP), internal integrated horizontal VCO circuit, ACL/ABCL selectable; digital analog OSD selectable, semi-transparent OSD, line/field pulse output to MCU for OSD; built-in 5V, 8V regulators to provide reference voltage for the whole power circuit; built-in MCU reset circuit and clock output circuit. Since many traditional components have been built into the IC, and SP633 IC and M61260/M61266 are all surface mount packages, the PCB volume is greatly reduced, which can save product costs.

In addition, the voltage synthesis (VS) tuner in Figure 1 supports PAL/NTSC/SECAM full-standard reception. Multi-standard decoding uses a single crystal oscillator, which can improve the stability and reliability of the whole machine.

The entire circuit of this LCD TV/monitor solution is basically debugging-free. All debugging and settings only need to be set in the factory menu of the machine using a remote control in the factory, which can save production time and cost, reduce investment in testing instruments and equipment, and reduce production defective rate and improve product stability.