Game console switcher

So one of the problems with modern tv's is that they never have enough inputs. Or maybe its just that I have collected too many game systems over the years. Anyway, several of my game systems aren't connected and its a real pain to try and connect them so the few that aren't in storage rarely get played. And I love the old school NES.

So this weekend I had a cool idea. Move all the game systems onto one of our side shelves and build an RCA switcher to make it easy to switch the inputs without having to move the tv. Several designs were contemplates such as a only school telephone type switching system where you would still have to get up and pull change cabled. The advantage of this is that it is super simple to build but its still annoying.

Another idea was to get a dial switcher similar to the ones used to switch between keyboards back when people had multiple computers but only 1 keyboard and mouse. While this would be much nicer to use its not very expandable and if there is anything I have learned over the years its that the number of game systems I will own is not going to go down.

I finally decided on a digital switching system that will have several buttons that can be used in conjunction with an Arduino to switch between the inputs.

The first step in designing it was to build a set of buttons that I could read using the arduino and light up an led to indicate which input was selected. So over the last two days I have been fiddling with some things. Originally I was connecting each button to a different pin on the arduino and using a pin to light a corresponding led. This was easy to build and worked well but because each button used a pin on the arduino its not super scalable. The arduino I have only have 14 digital io pins and 2 of them are reserved for system use leaving me only 12. This means I could have at most 6 systems connected... I currently have 4 and I am planning on picking up a PS2 from a friend in the near future.

Then i stumbled onto this Instructable which has a very nice solution. By stepping down the voltage using resistors in front of each button and using the analogue I/O pin I can chain the buttons together and use only a single button. Using the smallest resister I had on hand I was able to chain 4 buttons together and use up only 150 of the 1023 possible values. Each button steps the voltage down by ~ 30 values which is good because I need some space to minimize false positives.Using this technique I can chain together up to ~25 buttons which gives me a good number to expand out to. At this point the limiting factor is still the digital I/O pins to drive the switching and the LED indicators but with 12 I/O pins completely open I am not hugely concerned at this point.

I am still getting the occasional false positive but I think there is a little more work I can do to smooth the inputs. Now I have to figure out how to connect the actual cables using either relays of NPN transistors.

One thing I should mention is that the resurgance of electronics on this blog is the direct result of me picking up a new toy. A DC bench power supply :)

~(' ')~