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Enrique
01-26-2009, 01:21 AM
On the USB to serial converter an NPN transistor is used to drive the RESn line to a low state but nowhere does it say what transistor is it. Does anyone know?
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Thanks,
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Enrique

Leon
01-26-2009, 01:31 AM
Almost any general-purpose NPN should do, like a 2N3904.

Leon

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Enrique
01-26-2009, 01:54 AM
Thanks again

b.p.m.
01-26-2009, 03:43 AM
query: what USB to serial converter?!?

is there a circuit out that uses discrete components to convert USB to serial and where can
i find the schematic for it?

blake

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Phil Pilgrim (PhiPi)
01-26-2009, 04:30 AM
None with discrete components. All of them use an IC converter chip, such as the FT232R.

-Phil

Cluso99
01-26-2009, 08:21 AM
I use an P2N2222 - just be careful to get the correct pinout (the older 2N2222 used a different pinout).

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Rayman
01-26-2009, 08:34 AM
Has anybody tried using MProg to invert the polarity of the DTR signal?· It seems like it should work, but I didn't try it because Parallax didn't do it...

Phil Pilgrim (PhiPi)
01-26-2009, 09:21 AM
Yes, and apparently it works. Read about it here (http://forums.parallax.com/showthread.php?p=766645).

-Phil

Ariba
01-26-2009, 10:49 AM
Rayman said...
Has anybody tried using MProg to invert the polarity of the DTR signal? It seems like it should work, but I didn't try it because Parallax didn't do it...


I do it also on 2 self made PropPlugs - works well.
I have a 10nF capacitor between the inverted DTR and the RES pin.

Maybe Parallax don't do it, because it's cheaper to add a resistor and transistor, than program each unit with MPROG (or they just not had the idea?)

Andy