EE 308 - LAB 11

Setup for Additional Memory, Ports, and D/A Converter

In this lab you will put the necessary hardware on your board to enable you to add additional memory, ports, and a D/A converter to your HC12. You will use an 84-pin Altera chip for address demultiplexing, and to build additional ports. Two 32-KB static RAM chips will provide your additional memory. A D/A converter will give your board the ability to provide two analog outputs. Your Altera chip uses a 3.5 V power supply, so you will add a 3.5 V regulator to provide power for the Altera chip.

The HC12 uses ports A and B to provide the multiplexed address and data bus. When you use the HC12 in expanded mode, you are no longer able to use these ports. To compensate for this we will use the Altera chip to provide two eight-bit I/O ports.

The attached schematic shows how the parts are connected. The layout diagram shows how you should put the parts on your board. The wiring list shows which pins to connect.

Lay out the parts provided as shown in the layout diagram. Be sure to place the parts as shown - there is very little room for adding parts to the HC12 EVB, so unless you add the parts as shown, you may not have enough room to put on everything you need.

For the large parts (IC sockets and headers) solder two pins on opposing corners to hold the parts in place.

For the power and ground headers, solder all pins.

Solder the resistors, capacitors, and voltage regulator to your board. Make sure the leads are straight, and trim them to about the same length as the leads on the wire wrap sockets.

Place wire-wrap labels on the four wire wrap sockets, and the expansion header.

To wrap a wire onto a pin, strip about 3/4" to 1" of insulation from one end of the wire. Wrap that end of the wire onto the pin, making sure a small amount (about 1/2 turn) of insulated wire is wrapped around the pin. Cut the wire to the necessary length to reach the next pin, strip insulation from the free end, and wrap that end.

Use different colors of wires for different functions. It is common practice to use red for power and green for ground. You might use blue for AD0-AD15, yellow for A1-A15, white for control lines, and black for expansion ports.

Start with one group of pins (e.g., address), and do all wiring for that group before moving on to the next group. I did the wiring in this order:

Power and Ground
Control Lines
Expansion ports

Wire long wires first, short wires last.

Route wires around the outside of the sockets.

Do not daisy-chain power and ground lines from one component to another. Instead, fan out from a power or ground pin to the components.

Take a highlighter pin and highlight the wires you have run on your wiring list as you wire them.

After all the wiring is done, take an ohmmeter and check the continuity of all wires on the wiring list. (Check continuity after you've run the first few wires just to make sure your wiring technique is correct.)

Next week's lab will use the D/A converter. Make sure all wiring for this is done by next week.

If you can't finish all the wiring by next week, try to have all power and ground wiring done, AD0-15 from the HC12 to the Altera chip, and the expansion wiring (Altera chip to header J1). This will allow you to begin testing your wiring next week.

In two weeks, all wiring must be completed. We will finish the memory expansion in that lab.

Bill Rison, < >
Tue Apr 6 1999

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