The MC HCK is an entirely open source dev board based on the Freescale MK20DX32VLF5 which supports USB for easy programming. It features 8KB RAM, 32KB program flash + 32KB data flash. ““MC” is short for microcontroller, and “HCK” stands for “hacking”, “hackers”, “hackspaces”, but shorter, smaller. Like the MC HCK board itself.”
Its developers claim you can build it yourself for $5. You can check out their project repository to get the latest source and KiCad design files.
We note that the board is even Bus Pirate compatible as explained in Ben Gamari’s blog.
So you say its a Freescale micro, the one in the photo is a Nuvoton and the Bgamari blog talks about a STM32, are they all pin compatible or what?
The MC HCK has been mentioned before. The picture is the MC HCK revision 1 with a Nuvoton NUC120 whilst the revision 2 had a STM32L151. They’re up to revision 5 now which I guess is using a Freescale chip.
Ordering 2 mm PCB from seed adds extra $16. I’m wondering if 1.6mm would work with USB.
There are some compromises you’ll have to accept to get the price this low.
If you go for a thinner PCB then it won’t fit properly in the USB socket and won’t make a good reliable contact. If you’re happy to add a shim on the back or carefully insert it when programming then you can get by with a thinner board.
Same for the plating. If you just use the basic HASL finish then you’ll find that over time, the exposed solder on the USB “plug” portion will oxidise and give you a bad connection. Paying extra for ENIG finish will solve this problem but it is also quite a bit more expensive. If you’re happy to clean the contacts if the boards have been left out exposed then you’re probably okay to skip it.
The price for these two changes will bump up the cost significantly but you’ll have a much better device at the end of the day. It all depends on what you’re going to do with these boards I guess as to whether these changes are necessary. If you’re going to be selling these to the general public then you’ll probably want to do both changes or it’ll be a nightmare for returns and support.