I have a device that has a MC68HC705J1ACDW microcontroller on it that I would like to try to emulate in software. The device is a display unit that has a couple status leds and a seven segment display. I would like to route the 4 wire proprietary connector to a RS232 serial port on my pc so that I can write my own software to control the display. There is one button on the display, so I would need to emulate the communication in both directions. I am not worried about the software part, but I need to some help on the hardware side. I have a couple of questions, in case anyone has some insight for me.
- I am assuming that there is not a lot of communication going on, because of the small number of LEDs on it. Is it realistic for me to observe the data sent from the main device and learn how they communicate?
- How do I go about creating the cabling? I have determied which wire is power and which is ground. I am assuming that each of the others is for communication. How do I determine which is which?
- It seems to me that the only way that I can really look at the data being transmitted is to connect the source device to my pc via one serial port, the display via the other serial port, and pass the data through, while logging it. Is this reasonable? Is there freeware available to do this, or am I going to have to write it myself?
- Any books or online resources that I can use? I am trying to get a copy of "Serial Port Complete" by Jan Axelson, which is the only book I have heard fo so far that comes close.
I am sure that I have a lot of work ahead of me, and I am sure I forgot something, but thanks for any help.