| DL1DOW | German Amateur Radio Station |
 Only a few components on a breadboard are a fully usable Arduino |
When removing these from the board itself, the partlist becomes very short:
| 1 | ATMEGA 8 or 168 with Arduino bootloader |
| 1 | Crystal 16MHz |
| 1 | Capacitor 100nF |
| 2 | Capacitors 22pF |
| 1 | Resistor 10k |
| 1 | Pushbutton |
| 1 | Connector |
 That's how it looks like on a breadboard. |
The converter from TTL to RS232 signal level is a simple application of a MAX232 and fits inside a connector's housing.
 Cute USB Adapter |
 A look inside |
The idea came from [2] where a CAT-cable for a Sagem mobile was used as CAT cable for a ham radio transceiver.
When connected to a PC via CAT, many mobile phone use a serial protocol and TTL signal levels. At many of these CAT adapters, the connexion to the operating system is done with a virtual COM-port. So we may have exactly the thing we want for our Arduino: A COM-port with TTL signal levels via USB.
CAT-cable for the following cellphones have been tested:
The first step should be the installation of the COM driver. When opening, one needs a way to find the meaning of the connectors. One possibility is to look out for a scheme of the connector and mark the wires. Another, maybe faster, way is to identify the pins by oneself:
void setup()
{
Serial.begin(9600);
Serial.println("Setup ready");
}
void loop()
{
Serial.println("Loop");
delay(500);
}
