Machine Kit Router

This is a message passing / compute center for machines, robotics.

Board Design

I use the ATSAMS70 micro, which is very fast but still simple enough. 300Mhz and the I/O we need.

That said, setting up the power schematic is messier than I would like. There's an internal regulator on the chip that is externally connected to a few 'vddcore' input pins (5), each of which needs a bypass cap. In addition, there are 5 vddio pins that supply voltage to the i/o lines. These also get bypass caps. This is 10 bypass caps. That is a lot to place right off the bat. In addition, there are some pesky vddpll lines that ask for filtered inputs from either the main line or the regulator, meaning I have now inductors and more bypass caps. Oh my. Here is the schematic checklist diagram:

To do nice ADC things I want a well stabilized vrefp and vrefn, I will neglect doing this with this chip.

Setting up the USB successfully is nontrivial, as it can be a properly high-speed differential line. I have bricked a few of these chips trying to implement the usb operation, so I'm going to skip most of this as well... Maybe breaking out the USBDM and USBDP lines just in case I get bored later, but I kind of doubt that.

So, here it is. I didn't ask for this complexity. grumbling

Less talk more routing ... one note - I am putting some ground plane between all of the RX and TX lines, which I hope to be driving around-and-above 3MHz. So, I want them to not be coupling into eachother. Leaving some ground plane between each trace is a bit like shielding a wire... Here you can see two of the ports taking 'the dive' to the ground plane, where they have lots of room, and then being routed with some space between. I should update other boards using similar rules as well - I'm re-doing my BLDC driver and have started a stepper board that I'll be bringing up at the same time, so I can do that. Nice.

OK, here it is: