And many of us need a platform where we can develop our ideas. it looks quite different for all of us. Both boards are good, imho, I'd like Peter's P2D2 because of its compactness.
^^^^ This.
These are two very different requirements so you're always going to end up with two different boards.
My favorite parallax board was always the PPDB:
It has gotten so much use over the years and prototyped so many badge designs, evaluated so many different types of hardware... it's been a real workhorse.
Unfortunately, like most workhorses I wore it into the ground and killed the max232 / programming circuit on it so I ended up having to remove that entire section and just wired a prop-plug in. I wish I could get my grubby little paws on another...
I understand how you feel and it brings me great pain to see this wonderful board which slipped into obsolescence a few years back. It became difficult or impossible to get certain parts, costs were increasing (it was made in China), volumes were going down and it came on the radar of an internal spreadsheet we circulate four times a year or more. That spreadsheet has a name like "EOL / Obsolescence / Excess Inventory" and it's purely a financial view that pays no attention to marketing goals, product diversity, etc. It was painful the day decisions were made around this board, I assure you.
I'd really like to develop something like this for P2 once we get underway. Better yet, I'd like our customers and partners to do this job. We can't be dominating the board business this time around; it prevents the industry from growing as a whole in some ways.
I was generously gifted a P2D2 board, thanks Michael, Peter and everyone I don't know about !
Now the question is... how do we(I) get some (just one would do for now) chips to populate the P2D2s ?
Right, so I'd just have a large open circle (or octagon) encompassing both the VIO jumpers and the P2, so a fan can get air down there if need be. Or have a circle with 3 or 4 breakable tabs if you want to cover both options.
If you try and use idc ribbon headers to connect to the 12 pin headers, these have a keying tab (requiring a notch, or wider clearance), above the 12 pin headers.
I don't think it needs to be taller.
I don't think we need to allow for batteries at this stage; we can always use USB charge packs
I'm pretty sure the breakouts won't fit as-is. They use smt headers, with the P2-Eval hdr pins passing up through the bottom of the breakout PCBs.I think they'll need the perspex removed out to the edges.
I'll get you some models of the breakouts tonight.
Removing and inserting the microSD might be kind of a pain, you might want to have a cutout in that corner as well, or add in a quick 3D model of the microSD card to make sure it can be reached.
I'm pretty sure the breakouts won't fit as-is. They use smt headers, with the P2-Eval hdr pins passing up through the bottom of the breakout PCBs.I think they'll need the perspex removed out to the edges.
I'll get you some models of the breakouts tonight.
Thanks, yes compatibility with the breakouts is pretty important. :-)
Removing and inserting the microSD might be kind of a pain, you might want to have a cutout in that corner as well, or add in a quick 3D model of the microSD card to make sure it can be reached.
The SD card ends up being under a mm from the edge. I think it will be okay, will know for sure after I get one put together.
I'm pretty sure the breakouts won't fit as-is. They use smt headers, with the P2-Eval hdr pins passing up through the bottom of the breakout PCBs.I think they'll need the perspex removed out to the edges.
I'll get you some models of the breakouts tonight.
Some may also want right angle headers, so another reason for perspex removal to the edges.
Was the PCB laid out, with correct pin-numbers for right angle option ?
If you try and use idc ribbon headers to connect to the 12 pin headers, these have a keying tab (requiring a notch, or wider clearance), above the 12 pin headers.
Can you actually get 12 pin IDC cables and box headers ?
Seems to be 10 way, and 14/16 way choices there ?
Here is a first pass at a design for an enclosure. It is not complete, I thought I would put up a couple pictures now to get some feedback.
Looks good.
Can fat fingers reach the SD card ?
No air-flow slots over the P2, and where does the FAN mount ?
Should be able to reach the SD card okay - we'll see.
I think provisions for a fan needs to be on the bottom. Otherwise so much of the top piece gets cut away that there is not much left to justify making an enclosure.
Besides, wouldn't a fan be more effective on the bottom since there is an array of vias to carry the heat from the chip to the copper plane on the bottom?
W9GFO,
This is similar to what I was thinking of trying to design. Main difference is that I planned to have each side with the pins be cut out to the edge instead of just a hole for the pins.
There will be daughter boards that plug into the pins and go out off the edge of the main board and I wanted to allow those boards to have components on the bottoms, thus giving them more room by not having the enclosure go there at all. I was also thinking that the middle top would be completely open around the chip and pins so that you could put a heat sink on the chip as well as making it a little easier to plug into the pins there.
Fan goes on the bottom, but I think a heat sink on the top of the chip itself would help also. On my Pi 3B+ boards I have heat sinks on the top and bottom.
In case anyone doesn't know, this Amkor package we are using is designed to conduct heat out through a big metal GND pad on the bottom. That solders down to a land on the PCB which, in the case of this Eval board, has a 9x9 via array that carries the heat all the way down to the bottom of the PCB, where a 3oz copper GND plane spreads it across the entire bottom of the PCB. So, you'll want to cool from the bottom, not from the top.
If you try and use idc ribbon headers to connect to the 12 pin headers, these have a keying tab (requiring a notch, or wider clearance), above the 12 pin headers.
Can you actually get 12 pin IDC cables and box headers ?
Seems to be 10 way, and 14/16 way choices there ?
Comments
^^^^ This.
These are two very different requirements so you're always going to end up with two different boards.
My favorite parallax board was always the PPDB:
It has gotten so much use over the years and prototyped so many badge designs, evaluated so many different types of hardware... it's been a real workhorse.
Unfortunately, like most workhorses I wore it into the ground and killed the max232 / programming circuit on it so I ended up having to remove that entire section and just wired a prop-plug in. I wish I could get my grubby little paws on another...
I understand how you feel and it brings me great pain to see this wonderful board which slipped into obsolescence a few years back. It became difficult or impossible to get certain parts, costs were increasing (it was made in China), volumes were going down and it came on the radar of an internal spreadsheet we circulate four times a year or more. That spreadsheet has a name like "EOL / Obsolescence / Excess Inventory" and it's purely a financial view that pays no attention to marketing goals, product diversity, etc. It was painful the day decisions were made around this board, I assure you.
I'd really like to develop something like this for P2 once we get underway. Better yet, I'd like our customers and partners to do this job. We can't be dominating the board business this time around; it prevents the industry from growing as a whole in some ways.
Ken Gracey
Given we are resource constrained, the Parallax board will do it for me.
Now, if On can be somehow convinced... sign me up for both!
Now the question is... how do we(I) get some (just one would do for now) chips to populate the P2D2s ?
Otherwise, I do believe the rest are being installed on the Parallax boards.
J
Nice!! Count me in for one. : ]
What a beautiful piece of jewelry!!!
really nice work W9GFO
I like how you did the reset button
Those pins closest to the P2 will normally be jumpered, but you can also get long jumpers that have a finger tab coming off, that would work well if adjustments are required:-
https://www.altronics.com.au/p/p5462-header-shunt-pin-with-tag-pk-10/
Such as;
Is there enough rooms around the pins?
Should there be a hole in the center so you can touch the P2 to test for temp?
Should the enclosure be taller so that batteries or a fan can be placed underneath?
If you try and use idc ribbon headers to connect to the 12 pin headers, these have a keying tab (requiring a notch, or wider clearance), above the 12 pin headers.
I don't think it needs to be taller.
I don't think we need to allow for batteries at this stage; we can always use USB charge packs
IMHO, if any improvements could be made, both seems to be important.
Many people had commented about intending to try a heatsink, at the bottom side, I believe.
https://noctua.at/en/products/fan/nf-a4x20-5v-pwm
I'm pretty sure the breakouts won't fit as-is. They use smt headers, with the P2-Eval hdr pins passing up through the bottom of the breakout PCBs.I think they'll need the perspex removed out to the edges.
I'll get you some models of the breakouts tonight.
Thats a really nice fan with a good design life
They also have a 10mm thick version
(half the thickness, but noisy)
https://noctua.at/en/products/fan/nf-a4x10-5v-pwm
Thanks, yes compatibility with the breakouts is pretty important. :-)
The SD card ends up being under a mm from the edge. I think it will be okay, will know for sure after I get one put together.
Looks good.
Can fat fingers reach the SD card ?
No air-flow slots over the P2, and where does the FAN mount ?
Some may also want right angle headers, so another reason for perspex removal to the edges.
Was the PCB laid out, with correct pin-numbers for right angle option ?
Can you actually get 12 pin IDC cables and box headers ?
Seems to be 10 way, and 14/16 way choices there ?
I think provisions for a fan needs to be on the bottom. Otherwise so much of the top piece gets cut away that there is not much left to justify making an enclosure.
Besides, wouldn't a fan be more effective on the bottom since there is an array of vias to carry the heat from the chip to the copper plane on the bottom?
This is similar to what I was thinking of trying to design. Main difference is that I planned to have each side with the pins be cut out to the edge instead of just a hole for the pins.
There will be daughter boards that plug into the pins and go out off the edge of the main board and I wanted to allow those boards to have components on the bottoms, thus giving them more room by not having the enclosure go there at all. I was also thinking that the middle top would be completely open around the chip and pins so that you could put a heat sink on the chip as well as making it a little easier to plug into the pins there.
Fan goes on the bottom, but I think a heat sink on the top of the chip itself would help also. On my Pi 3B+ boards I have heat sinks on the top and bottom.
They do, see TE part 2-1658527-0 (mouser etc)
Mike