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Chinese characters based on the ISP chip design from time to time display devices

Print View , by: iSee ,Total views: 14 ,Word Count: 1322 ,Date: Sat, 6 Jun 2009 Time: 2:19 AM

1 Introduction

Chinese character display circuit commonly used in mobile communications and in public places such as the number of message display systems, display of traditional Chinese method is to adopt a common logic device (such as small and medium-sized TTL series, CMOS Series) according to the traditional design method of digital system design, or a single machine, single board computer, computer controlled, the main drawback is that the system size, power consumption, and high cost, low reliability, and the realization of a more complicated process. In this paper, a system based on programmable logic devices in the realization of the new characters from time to time programmable display device design, the display unit shows the minimum timing interval is 1 minute and cancel the timer display a decision by the Chinese characters in addition to pulse flip display speed. There are dozens of pages, each page at the same time show more than 100 Chinese characters, letters and symbols, through repeated programming different characters, letters and symbols indicate that occasion to meet the higher capacity of information and display the special requirements.

2 new characters from time to time the working principle of display devices

Figure 1 shows that for the characters from time to time the work of installation diagram, and its working principle is as follows:

Chinese characters based on the ISP chip design from time to time display devices

1Hz pulse as the timing of the CP input signal, the time schedule, minutes and seconds display, when the preset time, resulting in pre-pulse as a count of 1 count pulse, the output signal as the address to the number 1 election for the choice of Chinese characters Blockset the selected characters to the number of election Blockset device 2, for dynamic scan output, so the ISP device with limited I / O pin, the realization of a number of Chinese characters library module at the same time output to the LED through the distributor dot-matrix display shows the realization of Chinese characters. 2kHz pulse of the CLK to count 2, the output of the low three Chinese characters used to generate a binary module library, by decoding the binary high after the Chinese characters used to determine the location of the signature shows that, at the same time to the count of 3 pulses CLK, the output as a signal to address a number of election distributor device 2 and to achieve dynamic scan.

3 characters from time to time the realization of methods of display devices

The digital system uses a chip-based top-down modular design methods, apart from the distributor, the time shows that Chinese characters display, in Figure 1 are the design of other functional modules in Lattice's two ispLSI1032E devices, the devices have 6000 pld Equivalent door, 32 G LB, 64 months I / O client, a maximum operating frequency of 90MHz, selected Lattice Design Tools and Data I / O companies jointly designed the ispEX PERTSYSTEM design software application development. The software is a high-level design for CPLD design tools, which is based on Windows operating systems, the modular design supports a wide range of input methods, such as: schematic, VHDL language, Verilog language, ABEL-HDL language. Logic function of the software to support simulation, device simulation and logic synthesis timing, is an advanced design system CPLD. From time to time in the Chinese characters display circuit design, system design, including top-level function of the distribution system, the internal functional blocks of the interface connection and external relations, the use of schematic input; the bottom of the design using VHDL language can be completely or ABEL-VHDL language may also make use of ispEXPERT-SYSTEM features a powerful macro library to enter the schematic diagram. 

Figure 2 is a schematic diagram of the time to achieve pre-law function modules, the figure at 10, when a bit, at 10, sub-spaces can be a method used can also be used schematic design language, which counters the input from their respective output, output to line out that when the high, the time line out signal, through the line and column line connected to the realization of programming preset time, the figure for the function modules BZMK the pulse width to 1 minute changes in pulse width signal to other signals.

Chinese characters based on the ISP chip design from time to time display devices

Chinese characters based on the ISP chip design from time to time display devices

Figure 3 is a schematic diagram of the PWM signal to realize changes in the functional module, preset time high when the gate opened to allow an adoption of 1Hz pulse, counters count, schematic design with the width of the module is a combination of pre - circuit, the width of the preset time for the closure of the issue of low-level 1,2 gate, so that the necessary gate 2 output pulse width. 

The following is a method of using language to Chinese characters "in the" unit of Chinese characters as an example of functional blocks, shown in Figure 4. Chinese characters in the signature to determine the location, you can use the lower three counters (A2A1A0) to prepare to display Chinese characters. It is assumed that a character from 8 * 8 array of light spots of the show, a character from each word of 8 characters to form 8.

Chinese characters based on the ISP chip design from time to time display devices

Chinese characters based on the ISP chip design from time to time display devices

In the top-level schematic design, input and output buffers must lock the pin in ispLSI1032E, the technical line of this study are: the main part of the design of digital systems → have entered into the computer. JED file download → → ISP device in the external circuit printed circuit board design → Design → preparing for electronic devices and materials → installation, welding, assembly → debugging, verification. 

This article describes the use of programmable logic devices in the system design of precision programmable method of Chinese characters display devices, not only simplifies the hardware development and manufacturing process to significantly reduce the volume and improve the reliability of the system, the most important thing is can not modify the hardware circuit based on the design by modifying only the software, you can change the regular time display of Chinese characters to meet the needs of different users.

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