Right now, we only support 16MHz and 32MHz. This is primarily due to the fact that the we want the microcontroller IP to remain compatible with all of the existing libraries that are expecting a 16MHz clock. Handling the 2X speed is fairly straightforward, but other multipliers of the clock get tricky with a lot of libraries.
Would 32MHz work? Or do you need 20MHz or 22.1184MHz, specifically? Can you provide some additional details regarding how you want to use it?
32 is good. I’ve used the 22.1184 xtal on a 20mhz avr to enable 460.8 kbps. Good baud rate xtal freq. How bout bigger ram? Another uart? Mega328s did a lot for getting folks on board, but I’ve wished for several items that the uno didnt have…. this seems like a great way to get more of what a certain project needs.
There’s nothing that we can do about the available RAM based on the FPGA that we are using for XLR8. You can add an external EEPROM to the 8-pin SOIC footprint that is provided. I don’t know if that will really solve your desire for more RAM, though.
Standalone Xcelerator Blocks for communication interfaces such as UART, SPI, I2C are in the queue right now.
We just released our Quadrature XB late least week, and will be moving forward on the communication interfaces soon. Once the UART XB is out, you could build an FPGA image with multiple UARTs via the OpenXLR8 flow.