GALS for Electronics Hobby u. CHobby. In this article Steve tells us about GALs and how to get started with them. No we are not talking about female hobbyist or how to pick up girls. GAL is short for Generic Array Logic. If your home projects use logic parts then you will be interested in GALs. These parts may be the only device you need in your Logic parts bin. They are programmable to implement the logic of almost any logic device and they can do so much more. This article was submitted by  Steve Chamberlin as part of the Hobby parts for articles program. Steve will receive an Arduino compatible Really Bare Bones Board kit RBBB from the Modern Device Company for this great article. Vhdl Program For 8 Bit Up Down Counter D' title='Vhdl Program For 8 Bit Up Down Counter D' />In VHDL, a design consists at a minimum of an entity which describes the interface and an architecture which contains the actual implementation. Vhdl Program For 8 Bit Up Down Counter D' title='Vhdl Program For 8 Bit Up Down Counter D' />A GAL gate array logic is a hobbyist friendly reprogrammable chip thats perfect for creating customized glue logic for your electronics projects. If you often work with common 7. NAND gates, counters, and muxes, youve probably run into cases where you wished you could change just one little thing about a part, like make that active low output be active high, or change a synchronous clear input into an asynchronous one. Using GALs you can do this with ease. The Embedded Design Handbook complements the primary documentation for the Intel tools for embedded system development. It describes how to most effectively. Heres an index of Toms articles in Microprocessor Report. All articles are online in HTML and PDF formats for paid subscribers. A few articles have free links. In electronics, a flipflop or latch is a circuit that has two stable states and can be used to store state information. A flipflop is a bistable multivibrator. This VHDL program is a structural description of the interactive Four Bit AdderSubtractor on teahlab. The program shows every gate in the circuit and the. Cant find a source for some of the more obscure 7. No problem, create a work alike with a GAL. Is glue logic eating up too much space on your board You can typically replace 3 5 basic logic gates and similar parts with a single GAL. GALs are the simplest member of the programmable logic family that also includes CPLDs and FPGAs. They are the modern replacement for the one time programmable PAL devices that were first introduced in the late 1. Unlike PALs, GALs can be erased and reprogrammed many times. And unlike CPLDs and FPGAs, GALs dont require using a hardware synthesis language like VHDL or Verilog, or any other special design tools. Although its possible to use fancier tools to configure GALs, the simplest method is just to write logic equations in a plain text file, defining each output in terms of the inputs. Run your equations through a command line tool to create the binary GAL data, and youre ready to go. Easy as pie Youll find GALs in many varieties, but the most useful to hobbyists is the 2. DIP package. The 2. GAL is a 2. 4 pin 0. DIP, with 1. 2 dedicated inputs, and another 1. Youll find them at electronics suppliers like Mouser and Jameco for about 2 to 4 apiece. Futurlec also has GALs at very attractive prices. You dont need to know or understand the internal structure of a GAL in order to use one, but its interesting nonetheless. Knowing the internal structure of the GAL also makes it possible to work backwards from the binary GAL data to the original equations, if you ever need to reverse engineer a GAL program. Take a look at the schematic diagram of the 2. Lattice Semiconductordatasheet page 6, youll see its really a marvel of clever engineering. Each of the chips inputs is routed to a horizontal wire row within a large array. Each output has a small block containing a single OR gate fed by between 8 and 1. AND gates, with each AND gate fed from another horizontal row in the array. The array also contains many vertical wire columns. At each point where a horizontal and vertical wire cross, theres a fuse that can be programmed as opened or closed. By burning the right fuses, any input wire can be connected to any AND wire by means of one of the vertical cross wires, enabling the programming of an arbitrary sum of products equation, like Y ABC A B. In this notation means a logical AND, means a logical OR, and means a logical NOT. GAL equations are authored in a plain text file, using a format called EQN, and are then converted to a binary format called JEDCOM, or JED, which contains the fuse data. The DOS command line program that does this conversion is named eqn. You can find this tool through a web search, or just grab it out of the Opal Jr package here, part of a National Semiconductor tool suite. The syntax of a. Optional comment lines, beginning with a semicolon. A CHIP line, defining the chips name and type e. My. Chip 2. 2v. 10A list of symbolic names for each pin number An EQUATIONS heading. A list of equations for each output, one per line, in sum of products format For example, heres a. A 4 bit select input A is used to select one of 1. D, which is passed to a single data output Q. CHIP mux G2. 2V1. EQUATIONS q a. The mux example has a single combinatorial output, which is always enabled, but the 2. You can have up to 1. Outputs can also be used as input terms in the computation of other outputs. Additionally, outputs have an optional output enable term, allowing them to be connected directly to a bus that is sometimes driven by other chips. More complex examples of GAL usage in hobbyist projects are things like address decoders or peripheral interfaces. In my current project, I configured a 2. GAL as an 8 bit stack register for a custom CPU design. In a single GAL, I was able to implement an 8 bit updown counter with a parallel load input and an output enable. I also implemented the CPUs address decoder logic and some other control logic using GALs. Free Torrent Download Love Actually Sucks there. You can see the relevant. After youve written your. GALs are programmed using standard programming hardware, just like an EPROM or microcontroller. If youve got a decent universal programmer, chances are it already supports GALs. Unfortunately some of the most popular inexpensive programmers like the Willem EPROM Programmer dont support GALs, so check the list of supported devices carefully. I use the Easy Pro 9. B, which supports GALs as well as EPROMs, microcontrollers, and most other programmable devices. Once you start using GALs in your project designs, youll wonder how you ever lived without them. No other cheap, hobbyist friendly logic device offers the same combination of flexibility and ease of use. Where a CPLD or microcontroller would be overkill, and a pile of separate gates would cumbersome, a GAL is the perfect fit. David of u. CHobby I did a quick search for hobby programming options and found the following Comments Please Have you used any of these programmers Have a programmer or parts supplier suggestion for GALs Cool project that uses GALs Let us know with a comment.