P2 Module
DigitalBob
Posts: 1,486
in Propeller 2
Thought I'd take a crack at my own P2 module. Had a few issues at first the 1.8V reg. didn't work, found out the enable pin was wired low (Dah!), fixed that after replacing the reg. that whats going on with all the solder slop. Then I fired it up and checked for 20 meg at the crystal with the scope, showed 20 meg (Yeah Buddy!), after that the critical F7 ID hardware test, nothing Dud. Found out the test pin has to be wired low. Now it works like a champ, loads ram etc.
Comments
Added the flash and did a pin test, everything checks out, no more buying over priced modules, now I can run my own.
Well done, it's nice to try home grown stuff and you always learn things along the way.
Be aware that the P2 can draw quite a lot of current when its COGs are all loaded up and run at high speeds so some of your power traces might be a little light on if you need to crank it up.
Thanks, the pitch is a bit tight, this is my first proto so it’s a little sloppy. Parts are hard to get so I have to use regulators that where on the shelf. I don’t have pick and place so the smallest cap. or resistors are 603’s. I ordered some 200’s by mistake and I barely see them.
Yeah, that's keen. Well done, for sure.
Slight puzzle for me - It can't be a home brew etch surely, it's plated through. But why no resist?
The etch is not homebrew, I had a PCB mfr. make my design. It just got messy around the 1.8V reg. when troubleshooting it, not realizing I had the 1.8v reg. enable wired wrong.
Nice work! Don't think I would have attempted to solder in a P2 with no solder resist, but guess you made it work...
What's the back side look like? Do you have a ground plane?
Many Thanks, Under the P2 is a square ground plane. And another one on the back side with through hole connectors. To solder the P2 I just smeared the ground plane with solder paste, then align the P2 pins, after that I use a pencil iron to tack one of the corner pins, check alignment and tack a few more pins. Then I completely solder all pins shorted together on all fours sides. After that I use the desolder and suck out the pins. The final stage is fluxing all pins and then hitting them with the pencil iron, (flows like a champ) after that I flip it over and melt solder on the back side plane where the through holes are. Sounds unconventional, but works better than my hot air reflow.
This is how the bare board looks like. It's slightly bigger than I had planned, but the smallest parts I want to hand solder are 603's. Final dim. is 2" x 2.5". Pin config. are not really breadboard friendly, but no worries these are plugins for my main boards.
That sounds like the soldering proceedure I'd use, except I typically use solder wick to clean up excess.
By "desolder", do you mean a solder sucker spring thing, or a vacuum suction?
BTW: People used to give me a hard time about 90 degree angles on traces, but it worked just fine. Eventually switch to 45 degree corners to avoid complaints...
Wow, the tracks to the pins are nice and fat, and also being tinned, great for current capacity. Tough to cleaning up all solder bridges but you've clearly got that sorted.
I wouldn't even attempt to solder that tight, good for you (not a heavy drinker but my shakes would take over)
Regards
Bob (WRD)
Ray, I use the Hako FM-204, pricey but a great investment if your doing any kind of board work, its a must have. The key is using excessive flux (flux out the ying), I've replaced FPC connectors on the Ipad before with success (really small and tight pitch). I'll post a picture of my next one with All of the P2 pins soldered together in one continuous glob.
On my board I found it easy to use quite a wide solder chisel tip iron for soldering the 0.5mm P2, and once you solder the pins (and have bridges everywhere) then hold the board vertically and let gravity drain the excess solder onto the iron from the P2 above as you pull the iron's tip downwards. You need the pads to come out far enough from the P2 to do this and the solder mask helps bridging the tracks further out. Flux and desolder braid obviously helps too if required. It turned out okay on my P2ME2 board with this technique anyway.
Interesting... I can imagine that working very well. I want to get one of those desolderers now!
Could you please share the schematic diagram?
I don't have an actual schematic, I just did the artwork off the data sheet for each component.
This is a quick hand drawn Sch.. Note: use 8 ea. Ldo 3.3v reg., and tie all Vdd together and power off of one 1.8V, 2 amp reg., 1 ea. 4.7uf bypass cap. for each power line.