# Make your CueCat RS232 pod

### The purpose of this document is to describe how to make a small device that allows connecting a CueCat to a serial port.

NOTE : this serial pod only works because most modern serial ports are not too strict on the voltage levels representing a "0" or a "1" : in the definition of the RS232 standard, a "1" is coded with a voltage ranging from -3V to -12V, and a "0" is coded with a voltage ranging from +3V to +12V. Most modern serial ports will accept TTL levels as valid however, which means that they will accept 0V as a valid "1" (where they really shoudn't). Therefore, the pod's function is simply to invert the voltage coming from the CueCat's data line. If your serial port has stricter voltage level requirements, you'll have to replace the simple inverter with a specialized IC like the MAX232, to properly convert TTL to RS232.

The 2 advantages of this "incomplete" solution are :

- It can't be cheaper
- All the components are available at RadioShack, so you can buy them when you go pick up your CueCat :-)

  Here is the schematic of the circuit :

  Components you will need :

- 1 x 74HCT04 Hex inverter, RS catalog #276-2804 - $0.47
- 1 x Rectangular push ON/OFF switch, RS catalog #275-1565 - $2.19
- 1 x 1CB86 printed circuit board, RS catalog #276-0150 - $1.19
- 3 x AA single battery holder, RS catalog #270-0401 - $2.37
- 1 x Project box 4x2x1, RS catalog #270-1802 - $2.29
- 1 x Roll of double-sided foam tape, RS catalog #640-2343 - $1.99
- 1 x pack of 4 alcaline batteries, RS catalog #230-0873 - $3.19
- 1 x PS/2 extension cord - $1 at a computer hardware recycler
- 1 x DB9 <-> DB9 serial cord - $1 at a computer hardware recycler

  Total : $15.69

  Of course, you'll also need some tools, like a soldering iron, some solder, a phillips screwdriver, a drill, a knife ...

  1 - Preparing the project box

  The 3 battery holders together are just a little bit too wide for the width of the project box. So, you need to remove the plastic guides inside the box with a sharp knife or a cutter to gain 1 or 2 mmm :

  2 - Installing the battery holders and the ON/OFF switch

  Line up the 3 holders next to each other and stick 2 strips of double-sided foam tape under them. Then, stick the battery holders in the middle of the bottom of the project box (they will fit real tight but they will fit). Then, solder the wires serially to make a 4.5 volt source. Then, drill a hole on the side for the ON/OFF switch.

  Insert the switch in the hole, put the washer on and screw everything tight.

  3 - Making and installing the circuit board

  Solder the 74HC04 on the circuit board and wire it up according to the schematic above. Cut the PS/2 extension cord in half and use the half with the female PS/2 plug. Cut the serial code in half and use the half with the female DB9 plug. Once your board is ready, connect it to the power leads from the battery holders.

  4 - Installing the circuit board and getting the cables out

  Put 2 layers of double-sided foam tape on the solder side of the circuit board, then stick the board on the back of the project box's lid. On the side of the project box, dig a hole about 1cm deep and 4/5 mm wide. Tape the PS/2 cable and the serial cable together and slide them in the hold. You're about ready to close the box.

  4 - The box finished with a CueCat connected and powered up :)

  NOTE : if someone is willing to build a pod, take more photos and document the process better, it'd be great, the above explanations are really lame (but it's late (early ?), so I have an excuse :-)