M.2 Standard and the P2
iseries Posts: 1,349
in Propeller 2
It seems there are several company's using the M.2 standard to build card edge processor and devices.
Sparkfun has several processors and adapter boards that work with different devices that are also M.2 compliant.
If the P2 were to use this standard, I think the board could be made more compact and be able to be used with these sparkfun devices and carrier boards.
This could open up a new line of plug and play devices.
I agree, Mike. So much so that we made a mech prototype (adapter from our P2O design), to see what's possible. Photo below
There's a few real challenges - the available space between the divider in the M2 connector and the screw head means things are really tight across that line, but not impossible. A small insulating washer (mylar? nylon?) might be a good idea
Heat dissipation may be an issue. What I'm hoping is that some of the heat can be dissipated through the screw & solder nut, down to the ground plane of the board below.
Whoa, did not realize it was that small. Doesn't look like there is enough room for all the LDO's and regulators.
The 2 switchers (not LDOs here) tuck underneath, though i've done some preliminary layouts with ~2mm wide xtal-flash-switching reg all in one row that might also be possible to get to with a single sided layout
The real cause of the trouble is the dividing wall of the M2 connector - it intrudes a fair way into the board. Using internal or blind vias in that vicinity could fix that, though. And the P2 does have more pins than the M2 connector (several of the 75 pins are lost to power and keying)
Finally, the 1.27mm headers at top and bottom of the board are perhaps a bit redundant and could go. Its just that I prefer to be able to connect something direct to a board, even if its just the programming header and some I/O to blink a few leds. Thats something that annoyed me with the Intel Edison.
This is very interesting... The camera interface on these SparkFun boards looks perfect for P2.
Maybe I'd make the board bigger to include an FT231X... Put P2 on other side of screw?
This could make for the cheapest P2 board possible?
I guess heat dissipation could be a concern...
I agree Ray, I think the camera interface would be great to get going.
It may be possible to squeeze a 3x3mm USB<>Serial chip underneath. What would be more awesome would be to get something like Tinyusb going on the P2, that'd really save cost on all boards as well as avoid potential chip shortage issues
Not sure about this getting to be the cheapest, because it requires double sided assembly and miniaturized components like the all-in-one switching regs. However it does let P2 play in the Micromod space and ride that wave
That's certainly tight. Shame they chose such a location for the screw ?!
You can get nylon screws, but at the cost of thermal pathways, tho needing a nylon washer on the top acts as a thermal break anyway.
Heat transfer also depends a lot on the lower PCB design, which is 3rd party, and the image suggests a small pad with thermal reliefs rather than solid copper to planes.
It does look like the PCB can be larger, so the screw is not then on the edge, which would also help thermally and give more workable PCB area.
The function board has a larger PCB area, with the same connector, and better screw locations, but seems to have a subset default pinout.
Spark fun is great about posting their Eagle layouts…. Very tempting to try this out if they have Eagle files posted…
I'm thinking about a 2-layer board with P2 away from the hole, like this.
Even like this, not sure there's enough room for that though... Without putting stuff on the bottom...
Ok, that could certainly work and not have heat issues