Use a CPLD in your next design. Kenneth Maxon kmaxon@uswest. SECTION 1: INTRODUCTIONThe buzzwords these days in leading edge hardware are intellectual properties licensed. ASIC's and 'fitting' has nothing to do with your blue jeans. Let's. face it, most of us (the author included) don't have too much need for semi- custom ASIC's. Even now as the prices on development tools have plunged through the floor. However just last week I my jaw. This video walks through a simple 'HelloWorld' type of project with the Lattice MachXO2 FPGA/CPLD breakout board. A simple program is written that shows a binary counter with the LEDs, and the counter only. A CPLD is a combination of a fully programmable AND/OR array and a bank of macrocells that is reprogrammable and can perform a multitude of logic functions. Home : About Xilinx : Getting Started : CPLD. HCT- XX parts on his board. We talked for a few. CPLD's surfaced. CPLDs or Complex Programmable Logic Devices are the next extension to the PLD market. What's more, the silicon manufacturers are so interested in beginning. At the same time, entry level software. Public. Domain) Inter Net downloads while at the same time, continuing to gain in power. Fifteen years ago, the author started using programmable logic in his designs. Programmable Logic: Build Yourself a CPLD Module. Xilinx and Lattice all in one. The software needed to compile and program the CPLD is available for. Article Library > Programmable Logic for the Masses: Lattice MACHXO2 CPLDs Programmable Logic for the Masses: Lattice MACHXO2 CPLDs. The flagship toolset is the Lattice Diamond program. IspLSI Familie von Lattice; XC95xx Familie von XILINX; CPLDs verlieren beim Wegfall der Versorgungsspannung im Gegensatz zu FPGAs ihre Programmierinformation. Ein CPLD-'Programm' kann auf verschiedene Arten erstellt werden.A lot. has changed since then with the language syntax and different flavors of implementation. There are countless examples of how and when in- system programmable logic. This article is presented to kick. Towards that end, this article is geared towards the beginner. In this article the author will review some PLD & ABLE basics, language and syntax. AHDL language extensions, followed by a simple yet real world. PIA (Programmable Interface Adapter). To maximize the educational. SECTION 2: Article Overview. In this article the author will present an overview and all of the pertinent. CPLD's into the. readers next design. It is the author's hopes that this article can be used to slightly. Seattle Robotics Society as well as that of robotics amateurs everywhere. Section 1: Introduction. Section 2: This section. Section 3: This section introduces the reader to the basics of the ABLE. AND gates, Or gates, Inverters and other. Section 4: Test vectors and stimulus are introduced in this section to aid in. Section 5: This section introduces some of the more common ABLE languages. AHDL. More examples are included including. Section 6: This section focuses on the state machine architecture of AHDL using. ABLE basics and the AHDL primitives presented in the preceding sections. After a quick. discussion, a simple state machine is presented to load a byte in parallel and serially. Section 7: A change from the previous sections, this section focuses on the. Section 8: Specifics on the 1. Lattice are. given. Section 9: The author presents the final design of a PIA (Programmable. Interface Adapter) again using a 1. Lattice. NOTE: The author developed all of the code examples contained here in. If you find any. mistakes please contact him to correct this online document as a service to other readers. In a basic. ABLE script there are three types of syntax. The first type of syntax is file formatting. The second type of syntax is signal definition. And the third type of basic. ABLE is the equation. In this section, the author will present each of these. SYNTAX 1: Formatting overhead - The file overhead in ABLE is pretty minimal. All. that is required is a 'TITLE' line, an identifier at the beginning of the 'MODULE' &. EQUATIONS' sections and an 'END' terminator. The examples through- out this article are compatible with the Synario product line. Data IO. The author has chosen this content format as many of the more common. CPLD manufactures provide this product for free to support their chip sets, including. Lattice, Vantis and Phillips. The specific examples here were built and tested on the. Synario product that is provided by Lattice Semiconductor. These lines are present merely for use by the compiler itself. The same holds true in. ABLE, where the design engineer may define a signal or group of signals, fix them to a. Signal definitions must come between the 'MODULE' keyword and the 'EQUATIONS'. Keyword in an ABLE file. Refer to the formatting section above. A signal is defined as a signal name followed by a signal type. The signal type is. COM' or a node 'NODE'. Think of combinatorial signals. Inverters. Or- gates & And- gates are examples of combinatorial gates that work with combinatorial. Flip- flops and Tri- State latches are examples of gates that work with NODE type. Signals of type COM are usually assigned directly to pins of a package. SIGNAL. Notice the '; ' at the end of each line. Just like the 'C' programming language, if you. The above example defines three bit wide variables, named signal. To clarify. the above example a bit further we want signal. To distinguish it from. ISTYPE' operator. SIGNAL. There are some specifics to be aware of when defining output pins from combinatorial. Many of the earlier devices PLD's PLA's, GAL's etc had inverters that could be. To enable an inline inverter on a combinatorial pin uses the. INVERT' ABLE keyword. SIGNAL. Instead let. Sometimes the programmer wants to define an internal variable that has inputs or. These variables are defined through the use of. NODE' keyword. Nodes are also used for flip- flops and other clocked logic. An. important note, nodes are automatically removed from your logic by the compiler unless all. To keep this from occurring, specify the 'KEEP' modifier in the. ISTYPE' tag on the variable's definition line. The second, however, specifices to the. D' type flip- flop. More about. flip- flops in Section 5 (below). There are other types of node assignment to use with flip- flops, but most compilers run. D type flip flop. As the reader will discover later with descriptive dot. In the definition of an output pin, the type defined with the 'ISTYPE' modifier can be. REG. The. compiler will try to force the NODE to live with a particular output structure. As AHDL. which well deal with later is quite portable, and output structures change quite a bit, it. In a moment well examine equations to show how floating nodes are. Group: Often the designer has a group of signals that because of their number. This happens quite commonly on computer circuit boards where. It would be convenient if. ABLE provide this functionality by grouping as follows. To access just the top nyble of the. DAT. The same. applies for the OUT variable, although these have the 'COM' property that specifies them. In the example abvoe the choice of names for the variable DATA. These variables could just as well have been named Peter, Paul .. The order of prescedence is. SYNTAX 3: Equations - The third and final type of syntax used in ABLE is that of. Equations. Equations use standard Boolean logic operators to tie together variable nodes. ABLE source file. Equations defined in an ABLE source file must lie between the 'EQUATIONS' keyword. END' keyword. Refer to formatting syntax above. Some of the basic ABLE Equation syntax is listed below. XOR$ ASSIGNMENT= CLOCKED ASSIGNMENT: = COMPARISONS==,< ,> ,< =,> =,!= ADD+ SUBTRACT- MULTIPLY* DIVIDE/ SHIFT RIGHT/LEFT> > ,< < START/END BLOCK . Now let's. explore how to put some of this logic to use. Above in the section on variable definition we defined several single bit variables. Let's examine the simplest case, an inverter. From the. table above the operator for inversion is the '!' and it is implemented as follows. SIGNAL? Well remember in order for this to work, it must be combined. Syntax section #2) above and the formatting from. Syntax section #1) above as well. The combined file would look like. TITLE 'this example demonstrates a complete ABLE file for a simple inverter'. SIGNAL. Remember that if you want to test any of these. Now let's look at some of the other simple ABLE equation operators like OR & AND. SIGNAL. Merely half an hour or so and you're building chips to reduce the number of. Now let's include the signal definitions for DATA. In the following example the author will present equations to enable an output bit. SIGNAL. Several implementations of the same equation will be shown using differing. Take a few minutes to read through each one of these and appreciate the syntax. Note that when Synario evaluates an. SIGNAL. This is an important difference. ABLE, AHDL and other more complex lower languages where the input for unspecified. The following. example will make use of the rest of the signals defined in Syntax Section #2 above. Out. The design will implement a. The equations will also take advantage of the. Truth tables are a great way to quickly define the logic of a system when you. In the example below a nyble is decoded to drive a seven. The author will use some notation (specifically '. X.') that will not be. This notation allows. Dont Care reference. Also observe the definition of the temporary variables 'ACTIVE' and 'INACTIVE'. These addresses all in. A0. 00. The. same holds true for the effects of CHIP. The reader should. This will go along way to understanding where common errors are introduced in. As you can see the scalability of the logic is extremely large, and unlike all those. Later well look at how. CPLD chips offer in system programmability to quickly fix little mistakes. ABLE and the slightly empowered statements that make up the AHDL. SECTION 4: Test Vector Definitions & Simulation. One of the powerful operations available through the use of a high- level logic language. AHDL is the ability to generate test vectors. Test vectors allow the user to 'simulate,'. This section will deviate from the design. Section 5 later. Simulation of a design becomes paramount when the hardware must work correctly the. Imagine a CPLD that as part of its design controls an H- bridge configured. Sure you can rely on the programmer to get it right, but when. Reading through the article up to this point, the reader can see how easy the logic to. However, you've got the hardware wired up on a proto- board. Wouldn't it be nice to know that you are not going to. H- bridge before you actually cycle the power? This. is where Test Vectors and Simulation come into play. Defining test vectors and simulating them is a breeze. Test vector statements come in. First a statement that defines the symbols to display when running the.
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