Important ordering information: There is no minimum order, but in order to provide parts for as many people as possible, there is a maximum order amount of $100. Orders that exceed that limit will be automatically refunded. Also, as of March 2011, international shipping is now available. Shipments to the United States, Canada, or Mexico are trackable and insured. Shipments to all other countries are not trackable, and are also not insured.
College Board Information
An Assembled College Board (v2ps):
An Assembled College Board (v2):
Breadboard-Straddling
Breadboard-Straddling
Both versions of the College Board can easily be inserted into two breadboard sections with one set of power rails between them. However, to take full advantage of the College Boards' flexible I/O pin arrangement, you may want to cut a breadboard in half lengthwise, remove its power rails and attach each half to another complete breadboard as shown in the following two photos:
College Board (v2ps) Straddling two large breadboards.
College Board (v2) Straddling two small breadboards.
Notice that the College Board silk-screen labels identify the 28X2 I/O pin connections and that all I/O pins are duplicated along the top and bottom edges of the board. Since almost all the 28X2 I/O pins are bi-directional, this duplication allows you to install all your output circuitry on the top breadboard and all your input circuitry on the bottom breadboard, which greatly simplifies the wiring involved - just be sure to make your connections accordingly, and to not connect the same pin on both edges of the College Board!
Accessing the Input Voltage on the College Board (v2ps)
The 3-pin male header labeled "Vcc Out" (see top photo on this page) is used to enable access to the input voltage if desired. For example, if your project is battery-powered you can place the 2-pin shunt in the "ON" position and access the real-time battery voltage level (less the drop across the 1N4001 diode) at either of the Vcc pins on the edges of the College Board. By setting up an appropriate voltage divider, you can monitor the real-time Vcc voltage level via any ADC input pin. Warning: if you aren't certain of how do do this, it is best to leave the "Vcc Out" shunt in the "OFF" position. Applying more than 5 volts to any PICAXE pin can damage or destroy the pin, and possibly the PICAXE processor as well!
A second reason to access Vcc on the breadboard would be whenever you have peripheral circuitry that requires voltage levels greater than 5 volts in order to operate. Of course, you can do the same thing with the smaller College Board as well by simply connecting the battery lines directly to your breadboard. Whenever you enable Vcc access, it is most important to route it carefully on the breadboard. Failure to do so may result in damage or destruction of mis-wired components!
Ceramic Resonators
The PICAXE-28X2 does not require an external ceramic resonator to operate. Whenever there is no external resonator present, it defaults to its internal 8 MHz resonator. In fact, with a program running with (for example) a 20 MHz external resonator in place, the resonator can be physically pulled out of the College Board's 3-pin resonator socket and the program will continue to run at a speed of 8 MHz. To verify this, just write a simple LED-blinking program, run it, yank out the resonator and watch what happens!
The downside of the 28X2's flexible internal-external resonator features is that it is possible for your project to be running at a speed other than 8 MHz when you attempt to download a new file. If so, the download will fail to happen because it requires 8 MHz to operate. The solution to this problem is to do the following: Hold down the College Board's reset button, start the download and then release the reset button. This procedure works because the 28X2 always defaults to its 8 MHz resonator on startup or reset.
Connecting the College Board to a Mac or PC
In order to connect the College Board (or any of our PICAXE-related boards) to your Mac or PC, you will need to construct a suitable programming cable - just follow the detailed instructions presented here. If you prefer to use the AXE027 USB programming cable, the October 2009 installment of the PICAXE Primer column in Nuts & Volts Magazine includes directions for making a simple stripboard adapter that enables the AXE027 to be connected to the College Board's 5X2 header. The only required parts are a high-profile stereo connector and two 5-pin female headers. If you are experienced in constructing small stripboard circuits, you can probably make one just using the following layout diagram. If not, you may want to refer back to the October 2009 Primer Column.
Stripboard Layout For SUSB-5X2 Adapter
("X" indicates that the pin should be removed before soldering the header)
One Final Note
Both versions of the College Board are designed to take full advantage of the PICAXE-28X2'S bi-directional I/O pins. However, either College Board can also be used with a 28X1 processor if you prefer.