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<houkime>
sorry, was a bit deep in both IPC and IRL absolutely crazy stuff.
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<houkime>
Joerg-Neo900, ok, so, vapor-phase soldering.
<Joerg-Neo900>
yeah
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<houkime>
Joerg-Neo900, soldering is not the only purpose of the courtyard, it is also about positioning accuracy of PnP and ease of repair (where cool soldering methods are not always availible).
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<houkime>
I made myself a quick memo from all IPC I've read
<houkime>
now to make missing courtyards.
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<houkime>
wow, it seems like 2 LED controllers are actually one of the hardest components in the whole v2.
<houkime>
0.5 mm pitch BGA, and 6x6 balls, meaning likely 2 layer breakout with very small vias
<houkime>
i actually consulted Xilinx design guide on BGA breakout, and for such a thing it calls for 3/3 traces and 0.1 via hole diameter.
<houkime>
*0.1mm
<houkime>
however i compared this to a CPU and it is also .5 pitch
<houkime>
so this kind of thing is needed no matter what.
<houkime>
the only problem is that not every ocb manufacturer is able to make 0.1mm holes
<houkime>
*pcb
<houkime>
ok, will just do what metacollin did on LOWER and place microvias and necked traces
<houkime>
however for CPU later this will imply stacked microvias.
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<houkime>
bug in schematics - on keyboard scanner chip unconnected rows or columns should be pulled up via resistor to vcc.
<houkime>
for LED controller - there is actually an up-regulating internal LDO but it seems to be not used and pins for related components unconnected. Most probably intentional, made a note in sch.
<DocScrutinizer05>
we operate LEDs from Vbatt, no? So no charge pump needed for the LEDs we got there
<DocScrutinizer05>
there is a note in schematics
<houkime>
DocScrutinizer05, yeah, 3.5V. That's why i though it is intentional.
<DocScrutinizer05>
about LED 7 8 9 iirc
<houkime>
in keyboard scanner there another bug. IRQ is active low but it is not pulled up
<DocScrutinizer05>
check if the pullup is in CPU or chip
<houkime>
it might be pulled up on bb-xm but idk how to check that
<houkime>
probably in the bb-xm somewhere
<houkime>
will check the docks
<houkime>
*docs
<DocScrutinizer05>
search for beagleboard-xM schematics
<houkime>
it seems like this IRQ is connected to pin AG4 in processor which is mmc data pin 2. Seems like a random choice
<houkime>
processor on bb-xm has only 3 or so actual interrupt pins
<houkime>
+ GPIOs that can be used as interrupts
<houkime>
but if one uses GPIO as an interrupt one probably wants to provide a pullup
<houkime>
need to check how this is supposed to work.
<Joerg-Neo900>
CPU has no internal pullups?
<houkime>
Joerg-Neo900, for real interrupts there probably are. For GPIOs made into interrupts - don't know yet.
<Joerg-Neo900>
I'm pretty sure each HPIO has optional weak pullup, maybe even strong pullup and weaj and strong pulldown
<Joerg-Neo900>
GPIO
<Joerg-Neo900>
some pullup mandatory for "open collector" mode
<Joerg-Neo900>
btw the "IRW" from LED controller is pretty much useless
<Joerg-Neo900>
IRQ
<Joerg-Neo900>
needed pnly foer *very* special gimmicks that never were used or done in N900
<Joerg-Neo900>
like syncing audio to LED patterns
<Joerg-Neo900>
another "funny" detail: with N900 LP5523 "IRQ" you *may* fry the CPU
<Joerg-Neo900>
when you program LP5523 to output VDD there which is VBATT
<houkime>
IRQ going to strange places problem is not about LED controller but about keyboard controller - TCA8418
<houkime>
U1801
<houkime>
It goes to "13A" on v2 board, which is pin 13 on the main expansion header
<houkime>
which goes to AG4
<Joerg-Neo900>
kbd controller is special, we planned to use the TPS65951 IIRC
<houkime>
*pin 13 on the 28-pin unit of main expansion header.
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<houkime>
It may be that AG4 is in GPIO mode and MUX is set to 4
<houkime>
docs say that MUX selection is independent for each pin so it is kinda cool
<houkime>
If so that will be GPIO_134
<houkime>
which indeed can be used as interrupt provided that it has a pullup
<houkime>
which might be internal
<houkime>
checked DM3730 CPU docs. there are both pullups and pulldowns on GPIO
<houkime>
ok
<houkime>
however, unused rows on TCA8418 still need to be pulled up.
<houkime>
will add some.
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