Control emulation speed

[sepp89117]

Hi @blazer82 ,

first of all thanks for the great work!
I've rebuilt it a bit and use it with a 4 "TFT touchscreen. Depending on how I configure it, I have speeds of around 30% above and below 100%. Therefore, I suspect that somewhere there is a constant factor for reducing the speed is. Can you tell me where?

Thanks very much!

[blazer82]

Hi @sepp89117

There is no built-in mechanism to reduce or control the emulation speed. I have it running as fast as possible which for me is usually around 80% to 100%. That being said, since it's all running on a single core and there's quite a lot of data to transfer to the display for each frame, the PPU and its memory transfers have a huge impact on performance. For example, if you can't offload the SPI communication with the display to a DMA controller you'll see a big drop in the frame rate. Also, I did some tests once on an ESP32 which has two cores, running the PPU on one core and the rest on the other one. This got me a better emulation speed than the Teensy if I remember correctly.

I did not pursue this project any further because the performance just wasn't quite as good as I was hoping for.

Hope that helps.