Making a rotary controller

[amiman99]

I have a question about the rotary controller.

When making a rotary controller from scratch, with out reusing original Jaguar controller, do I need the diodes, and line buffers in my design?

I noticed that almost everyone is making rotary controller by modifying or using pcb from the controllers.

 

My goal is to reuse a broken NYKO Sega genesis pad.

[+Stephen Moss]

The reason people modify/use the PCBs from existing controllers is that it is easier then starting from scratch.

Yes, you should use the line buffer as it provide signal conditioning (no intermediate voltage then may be misinterpreted going to the Jag), as to whether or not you need the diodes depends on what Jag controller buttons you using, Which at a minimum I would assume as being A, B, C, Pause & Options in which case you do not need one for Pause but you will with the others as they are Wire ORed together. Omitting them will short all the column strobe line (J0-J3 or J4-J7) of the applicable controller port to ground when any button is pressed, which over time is likely to result in the failure of the outputs of the controller port buffer.

 

I also suggest adding diode 21 (from pin 2 of the buffer to J3) so that any correctly written software can automatically recognise it as a Rotary controller and either automatically use a rotary reading method or prompt you to change controllers if a Rotary is not supported instead of having to mess around with a standard controller to first to select rotary support. 

[amiman99]

Thanks

 

Is the schematic on this page correct?

https://forums.shoryuken.com/t/pinout-pcb-guide-for-padhacking-an-atari-jaguar-controller/182316/2

 

I only have 1 quad buffer chip, so I need to be selective in what buttons I'll use. I can skip up/down for sure.

 

[+Stephen Moss]

That Schematic is essentially correct albeit is a little messy, however U normally refers to one device so the use of U1 to U6 suggests 6 separate Octal buffers when it should be U1A, U1B, and so on as they are all part on one device.

 

You may find the schematic I created (attached) easier to follow, ignore the bit about referring to the Tech Ref for D21 fitting as that relates to an as yet unreleased update to the documentation.

Jaguar Rotary Controller.PDF

Edited May 1, 2020 by Stephen Moss

[amiman99]

Thanks

[Zerosquare]

On 5/1/2020 at 10:14 AM, Stephen Moss said:

You may find the schematic I created (attached) easier to follow, ignore the bit about referring to the Tech Ref for D21 fitting as that relates to an as yet unreleased update to the documentation.

Jaguar Rotary Controller.PDF 28.33 kB · 13 downloads

There are a few things missing in this schematic: the IC power pins (#10 and #20) and the ground symbol on pins #1, #15, #17 and #19.

[+Stephen Moss]

On 5/3/2020 at 4:36 AM, Zerosquare said:

There are a few things missing in this schematic: the IC power pins (#10 and #20) and the ground symbol on pins #1, #15, #17 and #19.

Good catch with the 0V connection on the OE pins, the software automatically connects the power pins to VCC & GND nets and thus hides them to keep the schematic clean. Trying to add them to the schematic could get messy but I could mention them in the notes.