I lengthened the cable for a PS2 controller by 50 ft with a piece of CAT5 cable. The analog sticks have developed a “twitch”. They sit centered, but have a tendency to jump to the maximum value in either direction, favoring the positive. I checked the step response of the tether to see if it was causing signal distortion. I’m getting a 15% overshoot and a 1us settling time on a 57kHz square wave signal. I got the most distortion at 200mV and 80 uA connected to a 2.4K ohm load. Signal quality improved as I increased the load impedance and the applied voltage.
Am I missing something? The signal seems more than clean enough to prevent interference, but the analog channels do not behave correctly. The discrete channels for the buttons are working fine, which leads me to believe this may not be an analog problem.
Did you try out this controller before you made the changes? Is this a wired PS2 controller. If so I know that many of these were not very accurate with their joysticks. They did not go back to the same zero points and they would wonder around a bit.
It is a wired PS2 controller. It also worked quite well before soldering in the additional length of wire. I’ve tried several controllers, some are better than others, but all have the same issues.
50ft is a really nice antenna.
you may need to add some emi filtering on one or the other or both ends.
the degraded analog performance could be due to noise being coupled from the power supply lines in the controller.
should probably point out that the signals to the controller are not differential so there is dubious benefit to using cat 5 cable.
If you were to pair each of the signals with gnd, meaining you could only have 4 signals +gnd using cat5 wire, it would be better than nothing.
a still better choice would be multi-conductor shielded cable with a braided shield that you could tie back to your system ground.
You might need to consider adding driver/receiver pairs (differential?), or perhaps just buffers. 50’ is a long way, it’s doubtful that the chips in the PS2 were designed to drive that long a cable.
I just completed a project that connected two micro controllers across a 1000’ cable. We ended up implementing RS422, when testing with RS232 I found that 40 ft was the largest distance that I could get communication at 9600 baud with a decent bit error rate and without the additional line driver/receiver.
The main problem is that the voltage differential doesn’t allow for much noise. The line is set at 5V and expected to receive around 3.3V typically. Therefore any noise that is induced into the line can alter the data being transmitted. Not to mention that RS232 was designed for short range communication and the capacitance of the line may exceed the maximum value for the protocol.
You can Google RS232/RS422 converters you will find that modules exist that you can simply connect wires to complete the conversion or you can get some ICs that will complete the task and develop the solution.
