I'm thinking of building a small synthesizer (MIDI in, audio out) where all the MIDI decoding and the DSP would be done in an FPGA, in order to get consistent performance and low latency. But I'd like to have a GUI on a small screen, one of those 3.5" TFT screens with resistive touch, and I'm afraid programming a GUI on an FPGA would be incredibly hard (how would you even do fonts? pixel by pixel?)
So I was thinking of having a regular processor to the side, one where I can use some pre-made graphics libraries. What platform should I go for? Are there any combo mcu + FPGA boards that are cheap and easy to program? I'm talking $35 kind of cheap, like the Waveshare CoreEP4CE6 board.
Any recommendations or pointers to previous projects would be great.