Hands-on CPLDs -Part I: Experimental rev counter （5）

Published:2011/7/21 1:14:00 Author:Li xiao na From:SeekIC

By A. Rosenkranzer

The PCB and future developments

A double-sided PCB has been produced specifically for this tachometer project. The PCB and component placement diagram is shown in Figure 3. Component mounting should be fairly straightforward but take care not to allow any solder debris to enter underneath the PLCC socket where it could short between PCB tracks. Correct orientation of the IC is important so ensure that the clipped comer of the package outline corresponds to the corner of the socket and silk-screen printed IC outline on the PCB. Ensure correct polarity of the LEDs, capacitors and diodes when they are fitted to the board.



When any circuit uses a line of discrete LEDs the finished project always looks a bit amateurish if the LEDs are not uniformly in-line. A good tip here is to firstly solder just a single leg of each LED in place. The board can now be flipped over and all the LEDs carefully bent or re-soldered into exactly the right position before the second leg of the LEDs are soldered.

The layout is not too cramped so there is no reason why this PCB could not also be used as a development platform to prototype other CPLD designs. Those of you however who are looking for the flexibility of a true evaluation board should not be disappointed by our EVA-board that we shall be featuring in a forthcoming article in Elektor Electronics.

In the second part of this article we will take a closer look at the CPLD internals and device programming.

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