n00b Sanguino Breakout Board Questions

Hi all - Just getting started with the Sanguino. I apologize if these questions are the type asked hundreds of times over, but I haven't had much success in finding answers.

- There is a terminal labeled VIN Safe. What does this mean / used for?

- I'm assuming that the terminals labeled VIN are used to provide a constant source of +5v, as opposed to the digital/analog pins that can be turned on/off.

- The breakboard board kit I bought did not come with the sanguino PCB, so the Atmega socket is soldered on to the breakout board. Is it correct to assume that I could solder some female headers to one of the rows of holes on both sides of this socket so I could plug in a regular sanguino board in the future? (Of course I would remove the atmega chip first. )

Thank you! Feel free to kick me if these answers can easily be found somewhere.

I forget what the VIN Safe means but I don't think that's it. Half way up either side of the atmega chip there are pins labelled 5v and Gnd. those are what I use.

Jeff,

No worries about questions.
If you look at the schematic, [sanguino.cc]
specifically in the subsection labelled "POWER SUPPLY" you'll see that the "VIN" (wired to the barrel jack) has a diode (to protect against reversed polarity) and then a regulator (7805) to regulate down to +5 VDC. The intention is that you could provide this terminal unregulated DC from a wall-wart or similar to power your sanguino, unless you were supplying +5 VDC power directly to the Vcc pin. Since wall-warts have no standardization as to polarity, the diode is good insurance for your sanguino. So, VIN (from a *DC* wall wart or similar) needs to be enough above +5 v to account for both the diode's drop and the 7805's drop. The diode probably eats ~0.7 v; I don't recall what a 7805 needs, but I suspect anything above 7.5 volts will do fine, but above +12 could heat up the 7805 -- so a heat sink on the 7805 is a good idea in that case.

HTH,

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Larry Pfeffer,

My blog about building repstrap Cerberus:
[repstrap-cerberus.blogspot.com]