Puma board building diary

Marcos' unmaintained, but still in-use, Puma for FreeEMS circuit board/hardware design!
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nitrousnrg
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Re: Puma board building diary

Post by nitrousnrg »

digikey parts arrived 2 days ago, and a solder station arrived this evening (yaay!) :-) I had a half written email for jharvey, but will be almost obsoleted by this post.

Well, before that, I've been trying to revive my second puma (that one was *really* messed up with bridges). I fixed the bridges with the new iron, and loaded the SM. It didn't work, though, and took me a while to figure it out that the crystal had one of its 4 pads without touching the board. Again, too much solder paste in the other crystal's pads made it go up.

/* how to check the crystal */
The PLL VCO voltage should be somewhere close to 1.15v. If you have 2.5 (full VCCPLL) then you have a crystal issue.

After fixing that, I reloaded the SM, and apparently its working (I can debug it and see the instructions that are being executed). However, it is locked in two instructions, not sure what they do. Its like a while (something);

(@FC96):
BRSET 0xCC,#32, *+6 ;abs=0xFC9C
(@FC9A):
BRA *-4 ;abs=0xFC96

I believe it compares the byte at address 32 with 0xCC. Now I have the assembly manual, but still have to lookup what is in the 32th byte,

So, I still don't know why it hangs like that. I wouldn't be surprised if the MCU is dead, at least in part. A pin (PA6) in the working boards shows a square signal, here shows a loud and clear 0v. I tried resetting it (to let power stabilize), no differences.

Anyway, I got tired of that so I put some time to test the oven properly. I hope to assemble something tomorrow (its 4:40am now)

This is how it looks. The rise time is slow, but reaches 230°C in less than 5'. At 4:30' (more or less) the solder starts to reflow, so its acceptable to me. I still have to try one more trick to check if the risetime gets better.

Image

With more °C/min I can try to follow a proper reflow pattern. No point in trying it with this sluggishness.

The weird values appear when I move the probe while opening the oven door to let it cool.
Fred wrote:+1 too mucho tiempo en la playa = no bueno ;-)
I can't work at beach hours! The workplace is between 34°C and 39°C in the day, I've a reflow oven inside this human oven, its a super efficient setup :p
Marcos
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nitrousnrg
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Re: Puma board building diary

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Today I've assembled another one (3rd) , and it has the same weird behaviors as the 2nd puma:

* Load and verify with the BDM works well, I can debug and see which instructions are being executed.
* Enters in SM mode without the LOAD/RUN jumper (it should run the firmware if the jumper is not present). That pin (PA6) should have square signal but i only see the '0v' part. When it should go to '1' (5v) i only see something like 50hz noise. The 'correct' square wave is 50hz too.
* I can load freeems firmware, rip it, and verify it successfully (with kdiff3), I just can't force the bastard to execute freeems code.

At least they look *much* nicer with the right amount of solder
Image
Marcos
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nitrousnrg
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Re: Puma board building diary

Post by nitrousnrg »

Perfect, it works. Again, it needed a pullup in the reset pin of the FT232.

I wonder who will get this board :-)
Marcos
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Fred
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Re: Puma board building diary

Post by Fred »

nitrousnrg wrote:I wonder who will get this board :-)
I don't want to be biased, but do the kiwi ones first, and ship a box of them to me. I actually need mine asap, and if the others are coming at the same time, then if you don't do them first, they are holding me up. My engine would be going in tonight, but it would be too noisy to do the work required at this time. So, tomorrow is a BIG day, engine back in, start modifying some accessory stuff, could have it running again on "Another ECU" in a day or two. At that point its firmware/software/hardware for freeems dawn till dusk until the truck runs it. In 2 weeks there is a meetup with some car guys - last time I was there one said "freeems, it'll be ready in 5 years" and it would be AWESOME to show up in my ute running Puma powered FreeEMS :-) Make it happen, Marcos, I'll do my share.

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jharvey
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Re: Puma board building diary

Post by jharvey »

Good job in keeping the orientation of the component text all the same. I see the MCU text is in a specific orientation, and doesn't match the silk screen. We should probably add that to the todo list for the next spin.

Looking good, and much cleaner now that you have the right components.

About the re-flow profile, what re-flow are you using? Is it a toaster oven? Is it a conventional, or IR oven? It looks a bit under powered, I have had good results with the Infrawave from Black and Decker. It has conventional and IR elements and is of a good size for about $90usd. Another possibility for a board this small, is a simple toaster. Disable the spring eject and put it on it's side. They also have a tendency to be IR and conventional, and can typically be picked up for short $ and at a local store.
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Fred
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Re: Puma board building diary

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jharvey wrote:Another possibility for a board this small, is a simple toaster. Disable the spring eject and put it on it's side. They also have a tendency to be IR and conventional, and can typically be picked up for short $ and at a local store.
ROFL - I love it! :-)
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nitrousnrg
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Re: Puma board building diary

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Fred wrote:Make it happen, Marcos, I'll do my share.
Perfect, next one is yours, and fully assembled.

jharvey: the silkcreen is backwards, as you noted, and mostly because of the MCU ¬¬

About the toaster, I measured mine, which heats up fast, but I'm not sure about how uniform is that heat. And I don't want to put paste in there (we use the toaster with food). It worths a try, though. My setup is a convection oven, it was a good compromise between capacity/power/price.
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Re: Puma board building diary

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In 2 weeks there is a meetup
Mmmm, shipping time is almost 2 weeks. Tonight/tomorrow I'm assembling yours, Fred. I have to check how long it took to Joseph Davis to have his board
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Re: Puma board building diary

Post by Fred »

nitrousnrg wrote:
In 2 weeks there is a meetup
Mmmm, shipping time is almost 2 weeks. Tonight/tomorrow I'm assembling yours, Fred. I have to check how long it took to Joseph Davis to have his board
How much extra would it cost to get them here faster? Given that it'll be spread across several people, maybe it will be worthwhile.
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nitrousnrg
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Re: Puma board building diary

Post by nitrousnrg »

the "fastest" is 13 days instead of 14 (regular), or 14 instead of 15. We could give it a try, tho
Marcos
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