Hi I am in the process of converting my setup to a dual ram setup, which means I would lose the second GPIO pins for the ram!
I am now in the situation of having an Ironclad board which uses the second GPIO like the analog board for providing reset user and menu buttons.
A functionality which I have by soldering pins in, exposed to my mini ITX case to get these buttons again in the case!
Once I convert to a dual ram setup I would lose this functionality. So i checked the circuit diagram of the Digital IO board. I think I figured it out how this thing works for the 3 buttons and leds, but I would need some crowdsourcing of knowledge just in case I missed something.
The central hub for the buttons and leds seems to be an I2c input/output controller which sends the various inputs to the mister over the arduino ports of the D10 Nano, interpreting the i2c signals and resetting the device showing the menu etc is done by the mister software, as well as sending the signals for controlling 2 of the 3 leds. (the controller is an MCP23009)
Now as far as I figured, the voltage and ground comes from the Arduino pins, the MCP23009 SDA and SDC ports are straight connected to the Arduino SDA and SDC ports, Reset pin is permanently on high.
Now the switches basically pull down single pins on press which triggers an i2c signal to the Arduino ports from the MCP23009!
Vice versa the Arduino ports basically lower via i2c signals to make then "shine". Voltage led is a different issue that one goes on when VCC goes on (resistor also is needed not to short circuit here)!
Now I basically can try to replicate this by wiring the 5 ports from the Arduino ports of the DE10-Nano into an MCP23009 and then add parts of what I have mentioned. The easiest probably would be to add a single button first which can pull down one of the button pins.
Thats what I have figured out so far, am I missing something vital or should this plan work? (of course I still need to figure out the Arduino pins, but that is doable by reading the de10 nano docs)
References I have found so far
https://github.com/MiSTer-devel/Hardwar ... ig_1.2.pdf
https://www.mouser.com/datasheet/2/598/ ... 108056.pdf
https://ww1.microchip.com/downloads/en/ ... 02121C.pdf