Abstract: The programmable logical component (Programmable Logic Device, is called PLD) is one new logical component which the 1970s developed, it was the modern digit electron system the important basis which to the superelevation integration rate, the ultra low power loss, the subminiature seal and the customization direction developed. Its application and the development not only simplified the circuit design, reduced the cost, enhanced system’s reliability and the secrecy, and has brought the revolutionary change for number system’s design method. CPLD (Complex Programmable Logic Device), namely the complex programmable logical component, it is the EPLD improvement component which the early-1990s appeared. Compares with EPLD, CPLD increased the internal segment, also has the significant improvement to the logical great unit and the I/O unit. Xilinx is in the world one of biggest programmable logical component suppliers, FPGA inventor. Product type entire, including: XC9500/4000, Coolrunner (XPLA3), Spartan, Vertex. In this paper, we through to aspect and so on CPLD development, structure, application and design cognitions, understood that CPLD the basic principle, and designs the CPLD off-line programming reads in the circuit diagram.
Key word: Complex programmable logical component CPLD (Complex Programmable Logic Device), scene programmable logic device component FPGA (Field Programmable Logic Array), electronic design automation EDA (Electronic Design Automation), hardware description language HDL (Hardware Description Language).
One. CPLD and function
Programmable logical component including scene programmable gate array FPGA (Filed Programmable Gate Array) and complex programmable logical component CPLD (Complex Programmable Logic Devic) these two types.
Has the fixed number input and the output any combinatory logic function may take output in programmable non-erasable storage PROM as the input search table way realizes, many realize the combinatory logic structure aberration to expand from this simple concept, but produces general using the VLSI density can realize on the PCB board several simple PAL interconnect function component is the PAL/PROM this kind of model expansion, is called PAL structure PLD, namely complex programmable logical component - - CPLD.
CPLD provides the logical resource are quite few, highest approximately 10,000. But, CPLD has provided below the special function:
1. CPLD has provided a bigger flexibility in the design process for the customer, because regarding CPLD, the design only needs to change the programming document repeatedly to be possible, moreover the design change’s result might see immediately in the work component. CPLD did not require the long pretage time to make the prototype or the official product, the CPLD component already placed on distributor’s shelf and may momentarily ship out;
2. CPLD does not need the customer payment soaring NRE cost and the purchase expensive mask group, because CPLD supplier when designs its programmable component had already paid these costs, and may continue many year lifespans through the PLD product line to share these costs;
3. CPLD permission customer when need orders quantity which needs, thus causes the customer to be possible to control the stock. Uses excessive stock which the fixed logic component’s customer will face frequently needs to abandon, but when will surge upward to its product’s demand, they have the possibility for the component goods supply insufficient institute painstakingly, and can not but face the reality which the production will retard;
4. CPLD in the equipment will even ship out there the customer later also to be possible to program. Is precisely because had the programmable logical component, some equipment manufacturer was attempting now to already install in the scene product increases the new function or carries on the promotion.
Two. Xilinx Corporation’s XC9500 series programmable logic component
In recent years, the programmable logical component in aspects and so on high density, high velocity, low power loss developed very quickly. In the CPLD aspect, Xilinx Corporation has promoted the high performance, the low cost XC9500[tm] series, as well as unified the extremely low power loss and the high velocity, the high density and multi-I/O in the single component the pin characteristic CoolRunner[tm] series. This series CPLD component needs the power loss is extremely low, and low in price, thus causes it regarding the cost sensitive, the battery power supply portable equipment (for example mobile phone and digit grasps assistant) to be ideal.
XC9500 the series CPLD component is Xilinx Corporation has the representative product, Figure 1 is the XC9500 series chip outward appearance chart:
Figure 1 XC9500 series chip outward appearance chart
Three. CPLD design and development
The XC9500 series programmable logic component’s internal structure as well as the succession question 11 did not introduce, what under us cared is the CPLD design and the development.
The CPLD component’s design may divide into the design input, the design generally to realize, the design simulation and downloading programs 4 steps:
1. Design input
The design input is the electric circuit which designs the designer develops the software request some form to express, and inputs to the corresponding software.
2. The design realizes
After design input, realizes the tool to map logic the goal component structure in the resources, decision logic best layout, choice logic and I/O function block connection wiring channel. The Xilinx design realizes the tool to complete these tasks by the extremely high automaticity, the design translation utility program restores all input file automatically, execution all essential steps has the CPLD disposition procedure.
3. Design simulation
This part of biggest functions are advantageous for the user to examine whether own design concept does obtain realizes. We may carry on the simulation in the design process to the overall system and even each module, if has the question, may revise the mistake very conveniently, but does not need to move the hands and feet on the hardware. The simulation does not consume the resources, does not waste the time, the solid then it will be possible programming logic component design and the development essence are.
4. Downloading programming
Downloading programs one is loads the design stage production JEDEC document to the programmable component, is this article key point. The component programming needs to satisfy certain condition, like programming voltage, programming succession and programming algorithm and so on. The ordinary CPLD component needs one kind of programming special purpose equipment (programmer) to complete the component programming.
The Xilinx business provides based on the IEEE1149.1, JTAG agreement (JTAG Boundary Scan) the CPLD programming reads. It by DSUB
- 25 connections and the downloading electric cable composition, CPLD which develops must on the development foundation plate carry on the programming, on the board must leave leeway the JTAG use connection (TMS, TCK, TDI and the TDO holding wire and so on). Such advantage is we can the reality machine debugging.
Besides Xilinx reality machine programmer, but may also design the off-line CPLD programming to read in (electric circuit like chart 2), it can carry on the programming to CPLD to read, but does not need to develop the foundation plate in kind, the foundation plate in kind designs when does not need to leave leeway the JTAG connection. This can save the foundation plate, reduces the product volume. Figure 2 designa circuit has the following several main parts:
1. Parallel interface
In Figure 2, we may see that to a Parallel parallel interface, passes through the data line and the computer connection with it. Actually in here, we
Figure 2 the CPLD programming reads in the total electricity schematic diagram
Figure 3 Parallel parallel interface chart
May also use other connections, for example Multilinx/Serial serial interface, as well as Multilinx/USB connection and so on. Here uses the port is also we use in connecting the local printer’s connection frequently. This connection has the 25Pin connection, its each Pin port’s signal as shown in Figure 3.
2. Bus/Buffer electric circuit
The JTAG signal, like TMS, TCK, TDI and TDO need to establish the Bus/Buffer electric circuit. This Buffer electric circuit has used the three states of matter electric circuit, such design causes CPLD to read to computer’s parallel interface not adverse effect, only when needs to read to CPLD carries on the data feeds output only then acts. When input/output signal data it is at the high-resistance condition, when must input the output data is at the low resistivity condition, guarantees
The card reads to CPLD, reads out needs the electric current. Bus/Buffer electric circuit as shown in Figure 4:
Figure 4 Bus/Buffer electric circuit
Figure 5 LED expression electric circuit
3. LED expresses the electric circuit
In the CPLD programming reads in the circuit design also to design has each kind of LED expression electric circuit. If establishes has green LED to express the power source output situation, red LED when the TDI signal is the L low level lights a lamp. When the red LED spot extinguishes expresses in the transmission data, this time cannot close down or pull out the tie cable. LED expressed that electric circuit as shown in Figure 5.
4. Device cut electric circuit
(For example PC84, PC44 and so on) carries on the programming to the different CPLD chip to read, its choice completes by the revolving cut switch, because the length relations do not give.
Fund subsidization: This article by Jiangsu Province university physicism direct plan project subsidization, serial number: 05KJD510122
This article author innovates and the economic efficiency: Designs the CPLD off-line programming to read, carries on the programming to CPLD to read, but does not need to develop the foundation plate in kind, the foundation plate in kind designs when does not need to leave leeway the JTAG connection. This can save the foundation plate, reduces the product volume.
Teacher Zhou Jie comments: This schoolmate in writes this article in the process, the reading massive related books, through to aspect and so on CPLD development, structure, application and design cognitions, understood that CPLD the basic principle, and designed the CPLD off-line programming read in the circuit diagram, had certain innovation thought and the economic value.
Reference:
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[3] Sun Hang. “Xilinx Programmable Logic Component’s High-level Application And Design tactics”. Electronics industry publishing house, 2004.8. TP332.1
[4] Zhao Yanxiao winter glory. “Several Kind of Network control System’s Comparison And Model Application”. Micro computer information .2006. (4-1): P40-42.
