I am trying to connect an LCD hat made for Mega2560 to an Arduino Uno

[JulianDavis]

I have a TFT LCD hat module made for the Arduino Mega2560 laying around and I want to use it for a quick little project. I also have an Arduino Uno R3 and an Arduino Nano, but not Mega2560 onhand.

I am very fluent in C programming and I am good at a high level with hardware and also some low level hardware concepts but I am still learning a lot.

I understand that MCU's operate on "ports" and that the Arduino framework abstracts ports away from the user. I also found this Instructables article that mentions soldering some wires on to breakout the ports on a Nano board. I have spare Nano's around and if I can make it work I would love to use those for this project rather than the Uno.

I have looked through the code a while now and I can not find where you are defining the LCD data pins to their respective pin number on the Uno or the Nano. Since I can't slot the LCD on like a hat I need to be able to wire it up correctly. I understand that I can define cs, rst, wr, and rs in the constructor but I don't see anywhere I can define these data pins in the software. Are they implicitly assigned to a PORT and they can't be changed?

Thank you very much for your time.

[moononournation]

The databus class AVRPAR8 and 16 are using port directly.

[JulianDavis]

Oh I think I see now. This constructor takes a port argument, so I need to provide it A, B, C, or D. I already wired my circuit up to use the D port for D0-D7 so that is really helpful. I totally understand the constructor now. Thank you so much!

I found a datasheet for the ILI9486 and I was wondering if it's possible to connect a 16-bit parallel display like the board I linked above but only connect/use 8 of the data pins? I can read the datasheet if necessary but I was curious if you had any experience to know right away if this is even possible.

---

After looking at the datasheet it seems like I would need to set the interface mode or pins IM2,IM1,IM0 to get the correct bit mask for the mode I want. The driver IC seems to be underneath the screen and I can't view it. Maybe I can somehow find a trace of it on the top of the board? I am comfortable soldering and I have a microscope but I don't know where to expect that trace to be, if it's even there at all...