Digital signal processor (DSP) is the result of the fusion of digital signal processing theory and VLSI technology. At present, DSP technology is widely used in communication, voice, image, aerospace, instrumentation and other fields, and is playing an increasingly important role in promoting the digitization of contemporary information processing.
In the field of low bit rate multimedia communication using video lines to transmit video images, if you choose a dedicated chip for image processing, such as SAA7110, 8 × 8 3104VCP and LSI ’s dedicated chip, or use a high-end DSP with high-speed computing performance for Image processing will greatly increase the price. This article introduces an image acquisition card using TI's low-end DSP chip TMS320F206 and video A / D chip TLC5510, which provides an inexpensive solution for low bit rate multimedia communications.
1 Brief introduction of TLC5510 chip and TMS320F206 chip
1.1 Introduction to TLC5510
The TLC5510 is a CMOS, 8-bit, 20MSPS analog / digital device (ADC), which utilizes a semiflash architecture. The TLC5510 is powered by a single 5V power supply and consumes only 100mW of power. It also has an internal sample and hold circuit, a high-impedance parallel output, and an internal reference resistor.
Compared with flash converters, the semi-flash structure reduces power consumption and chip size. By implementing the conversion in a 2-step-process, the number of comparators can be greatly reduced. The waiting time for converting data is 2.5 clock cycles.
No external reference voltage source and precision resistors are required, and only the internal reference resistor and VDDA can achieve a full-scale conversion range of 2V. The linearity error at 25 ° C is ± 0.75LSB, and the maximum linearity error over the entire temperature range is ± 1LSB. The differential linearity error at 25 ° C is ± 0.5LSB, and the maximum differential linearity error over the entire temperature range is ± 0.75LSB.
1.2 Introduction to TMS320F206
TMS320F206 is a DSP chip launched by TI. It is a high-speed fixed-point digital processing chip based on TMS320C5x. It has the characteristics of an improved Harvard structure (parallel separate program and data bus), high-performance CPU, and efficient instruction set. Its main features are as follows:
The CPU has a 32-bit CALU, a 32-bit accumulator, a 16 × 16-bit parallel multiplier, three shift registers, and eight 16-bit auxiliary registers.
The memory has 224K words addressable storage space, 544 words on-chip DRAM, 4K words on-chip SRA or 32K bytes of flash memory.
The instruction speed is 50ns, 35ns and 25ns single instruction cycle.
Peripheral circuits include software programmable timers, software programmable wait state generators, on-chip phase-locked loop clock generators, synchronous and asynchronous serial ports.
2 Hardware interface circuit design
2.1 TLC5510 front-end circuit design
The TLC5510 front-end circuit is shown in Figure 1.
In the circuit, the analog power supply VDDA and the digital power supply VDDD are independent of each other. Between VDDA and digital ground AGND and between VDDD and analog ground DGND, 4.7μF capacitor, 0.1μF capacitor and ferrite magnetic ring are used to decouple and eliminate power supply ripple. AGND and DGND are separated to avoid the digital signal from bringing noise to the analog signal. The amplified video signal is directly added to the 19 pin of TLC5510. The clock signal of TLC5510 is provided by the clock signal output pin CLKOUT1 of TMS320F206.
2.2 TLC5510 and TMS320F206 interface circuit design
The interface circuit diagram of TLC5510 and TMS320F206 is shown in Figure 2. 
The TLC5510 digital ground is connected to the TMS320F206 ground. Because there is a digital output buffer inside the TLC5510, the pins [D1: D8] gn TMS320F206 pins [D0: D7] of the TLC5510 are directly connected. The CLKOUTI pin of TMS320F206 provides a clock signal to TLC5510 through a small resistor. TMS320F206 pins A11 and IS are logic control. When A11 is logic high and IS is logic low, TMS320F206 can read sample data from TLC5510. funcTIon ImgZoom (Id) // Re-set the image size to prevent the form from being broken {var w = $ (Id) .width; var m = 550; if (w <m) {return;} else {var h = $ (Id) .height; $ (Id) .height = parseInt (h * m / w); $ (Id) .width = m;}} window.onload = function () {var Imgs = $ ("content"). getElementsByTagName ( "img"); var i = 0; for (; i
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