SXmicro.com

A data sheet can be confusing and overwhelming for a newcomer to hobby electronics and robotics. Data sheets may contain text, graphics, Greek characters, numbers, and charts and it can be difficult to understand what exactly they are all trying to tell you. The data sheets for the SX20/SX28 and for the SX48 are no exception to creating the overwhelmed feeling. Let’s take a few posts to break down some of the information in the data sheet.

In general, a data sheet contains the following items:

• Product overview and key features
• Electrical characteristics (minimums, typical, and maximums for the various operating parameters)
• Part naming, numbering and packaging schemes
• Pin assignments and descriptions
• Example circuits and connections
• Performance characteristics (usually where you find the graphs)
• Packaging dimensions and footprint sizes

Sometimes data sheets are long and sometimes data sheets are a page or two or three. In the case of the SX microcontroller data sheet, it is 50 to 60 pages. The reason for the lengthy data sheet is because of the detailed descriptions of the hardware and instruction set.

For just starting out with the SX, you may not want to get too deep in the data sheet. Memorizing and completely understanding the entire data sheet isn’t necessary in order to work with the SX. It is important, however, to keep a data sheet handy and to review it every now and again. Reviewing the data sheet regularly will help you to learn further about the SX. If you haven’t looked at the data sheet yet, go ahead and download it. I recommend reviewing the first 8 pages as a start as it will help you become familiar with the SX family.

Here is a picture of the SX microcontroller ICs.

As you can see there are a couple different types of chips and packages. There are four different ICs total in the SX microcontroller family. There use to be a couple more, but that is a different story. In the picture you can see an SX28AC/DP-G which is the tallest and longest IC. This IC is a through-hole dual inline pin package (a.k.a. DIP). The SX28 has 20 I/O pins. The other three chips are in SMT packages. The one on the left with pins around the whole package is an SX48BD-G and is the biggest SX chip produced with 36 I/O pins. The blurry chip at the bottom of the picture is an SX20AC/SS-G and has 12 I/O pins. The remaining chip on the right is an SX28AC/SS-G. This IC is just like the DIP IC, but in a surface mount design.

As you may be able to tell from the naming scheme and picture, the SX48 has 48 pins, the SX28 has 28 pins and so on. The “-G” denotes that the IC is lead free or RoHS compliant. The DP/SS/BD is an abbreviation for the type of package the IC is such as DIP, SSOP and PQFP. If what I said is confusing, you can find the same information in the data sheet for the ICs on Parallax’s web site.

Here is another photo of the ICs, though not as good. I turned the flash on so you could see the labeling on the IC.

As previously mentioned, I received an SX Tech Tool Kit. This kit has everything one could want for getting started with the SX microcontroller.

Shown in the picture are the the two books that come in the kit. The first book, the spiral bound book, is an overview of the SX development system. The book has instructions on how to use the SX-Key (the programming device for the SX) as well as an overview of the SASM (the SX assembly language). The other book is “Programming the SX Microcontroller” by Gunther Daubach. This is the foremost guide for programming the SX micro in ASM.

Also shown, but hard to see, is the new SX-Key USB (in the upper right). This is the device for programming an SX microcontroller. This device is new and connects to the Windows PC via USB. In the past a serial port was used, keep this in mind as you go through the “SX-Key Development System Manual” as it makes many references to serial and not USB. A USB cable is also included in the kit.

There are two other items pictured that make this kit worth the price. One is the SX Tech Board. This is PCB with plugs for the SX-Key and DC Power. The PCB has a place to mount an SX IC and a small bread board. No doubt the SX Tech Board will be used heavily while we prototype circuits and write our first few programs for the SX. The other device that has a “Cool” factor is the Robolympics Medal. In the past Parallax has sponsored the Robolypmics and provided these cool medals to the winners. The medal has an SX microcontroller and a LED dot display for scrolling text and graphics. Also included on the medal is a little buzzer for making sound.

Not pictured, but included in the kit are a couple SX 28AC/DP ICs for use with the SX Tech Board or in your own design as well as a couple resonators.

Wow! Can you see the value in this package? Everything needed to get started in learning the SX micro is here. Wait…..there is one component missing. Did you catch what it is? The DC power supply of course. Parallax doesn’t send a power supply with the kit. This is great because it reduces shipping costs and it makes the kit appeal more to international customers. I am sure most of us have a DC wall wart plug sitting around that can be used to power the SX Tech Board. The board requires a center positive, 9V DC max power supply.