Convert a NES gamepad to USB with Arduino

Step 4 Testing

I highly recommend that you spend the extra time and hassle to hook up 10 wires to the nes pad and plug them into your arduino board and make up the usb ciruit

A note about usb cables, or any other cable, don't trust the colours, use a meter to find out which wire goes to each point on the plug, in my case the wires are not even the correct colours so it does not matter, but I have also had a keyboard that had wrong colours and wrong printing on the pcb!

Connecting the controller is tedious, the usb hardware is easy, either way its good to know it functions, cause after this its pretty much the point of no return

SO TEST IT

Take note that the cathode of the diode (the end with a stripe) needs to face into oncoming current, and the anode needs to be connected to ground

this is backwards from most diodes, what is happening here is the zener diode has a very low reverse breakdown point, so it "leaks" a controlled amount of current backwards through the diode to ground, which also drops our voltage down to the 3 ish volt signals expected by usb

Comments

[kirreböna]

Hi! I'm having some trouble understanding the schematics here, it seems to me that they are showing quite different setups? And I can't find an arduino pin 14 either?

[osgeld]

I double checked, they are showing the same thing, but the breadboard layout makes it look harder than it is

also digital pin 14 is analog pin zero (d15 is a1 etc to 19)

[shaggs31]

I've looked at this as well and agree with kirrebona. In the two schematics arduino pins 2 and 4 are not going to the same place. In the bread board you have pin 2 going to D+ and pin 4 going to D-. In the other pic you have them reversed. I might be wrong but I do not want to follow the wrong one. Some imput would be great thanks.

[mattgilbert]

Yep, the breadoard image and the schematic image apparently have pin 2 and pin 4 reversed. I'm not sure which is correct (or where in the code/library those pins are chosen in the first place). Also, the diode on pin 4 in the breadboard image is connected to power, rather than ground. Please clarify the pin4/pin2 connections.