start button for SMS games

[Yfrid]

just an idea, i would like to make a SMS>MD cartridge wich allows to use the start button from the mega drive controllers in SMS games. this is how it should look:

the only difference to a common official/homemade adaptor is that it doesn't have an extra button to pause, but it does have an extra cord with a passthroug plug for the controller port. So, when i press Start on my controller, it will give the input on the specific pin as supposed to be.

but, would it be possible at all? if the start button input is too complicated to reverse, C button would be easier? thanks!

[villahed94]

well, start would make it, but you need to add a cap there as the original has for pause

[NCrouther]

The select line must be pulled low to get start and C button values. I would assume that master system does not pull the line low, so the Genesis in MS mode would not do it either. You would therefore need some logic or a small microcontroller to poll the controller and demultiplex it so the correct signals could be sent to the controller port and to your cart-slot passthrough.