I'm trying to make a board that will connect a teensy 3.5 to a standard RAMPS 1.4 board. I'm running it with Marlin ported to the teensy (https://github.com/teemuatlut/Marlin/tree/32bit-HAL). I can get the X and Y steppers working fine. Z and Z2 don't work right nor do the endstops. I'm not worried about those since it's probably just a mistake in configuration. There are 2 areas I cannot figure out. I cannot read the temperature. It's a constant 235 degrees. I think I'm no understanding the proper usage of AREF. I also cannot control the heaters. I don't think I am using my mosfet drivers properly. I bought some TLP4227G optocouplers for this purpose. No matter what, the heaters are running. I've attached the eagle files for my setup. I'm not an electrical engineer, so I'm learning this as I go.