Status: Under development
License: Custom Licence
The goal of this project is to create a low cost and simplified XCore-200 development board using KiCad. Since I'm a fan of open source (and commercial EDAs like Altium are ludicrously expensive) I decided to use KiCad. I started this project around May 2016, when I decided to teach myself PCB design. While I was doing research and trying to decide on a good starter project, I stumbled upon Xmos and thought it seemed like a very interesting MCU architecture. However, when I saw that the XCore-200 Explorer Kit was over $100, I thought it must be possible to make a more affordable version. Yes, there is the StarterKit, however that is for the older XS1 series. There are many projects based on the StarterKit but I've not seen many based on the XCore-200 series. My hope is that by providing a stripped down and inexpensive development board, hobbyists would be more inclined to try out xmos, thus growing the community. If nothing else, it has already proven to be a tremendous learning experience. This project has so far proven to be way more involved than I initially expected, however I like a good challenge.
In order to make the board as cheap as possible, I have removed all extraneous features found on the official dev boards, such as USB, Ethernet, servo drivers, etc. All that remains is the XL208 mcu (the least expensive of the XCore-200 family), QSPI flash, XSYS/JTAG interface, power supply for 3V3 and 1V0, and the GPIO pins broken out to pin headers. A secondary goal is to make the board feasible to assemble at home using the toaster oven method, and possibly also with a hot air gun or hot plate. To achieve this I selected SMD components that have pins (as opposed to BGA or QFN), and hopefully will be able to fit all components on the top side of the PCB. I found that this goal does conflict with the first goal of low cost, since in several cases I found that the QFN/BGA components were cheaper than their equivelant packages with leads. Therefore the next revision will use all leadless packages, and hopefully it will still be possible to assemble at home (have not yet tried soldering QFNs).
Currently, I'm finishing up the schematic and am almost ready to start routing the PCB. Once everything is more complete, I will upload all of the related design files, for now just the pdf of the schematic. The schematic I've uploaded still needs tweaked, polished and double checked, and test points added but is done enough that I feel ready to request feedback from the community. I am getting 1 ERC warning that the PLL_AVDD is not driven, but have not yet figured out why this is. This is my first circuit board design, so please look for all kinds of mistakes, big and small, and I would appreciate if any feedback would be as detailed as possible.