Hardware Questions

NETMF & Gadgeteer
1

Been trawling the docs but I cannot find an answer to my simple design questions!

  1. What is the maximum sink/source current for an general purpose I/O pin in output mode?

  2. Can I just hook up a CR2032 lithium button cell to the RTC VBAT pin?

  3. Are there any special considerations that need to be taken to hook up a piezo to the IO10/Piezo pin?

  4. What does the alarm pin do?

Thanks.

Regards

John

2

If you can’t find it in docs then just ask here and we will help :slight_smile:

[quote]1. What is the maximum sink/source current for an general purpose I/O pin in output mode?
[/quote]
4mA. You can go a but higher but then the voltages drop.

[quote]2. Can I just hook up a CR2032 lithium button cell to the RTC VBAT pin?
[/quote]
Yes, any 3V battery will work

[quote]3. Are there any special considerations that need to be taken to hook up a piezo to the IO10/Piezo pin?
[/quote]
No but it is always good practice to add small resistor.

Good one! We have just added support to alarm so you will eb able to use this pin in next release. This pin goes high when the alarm you have set have fired. The special thing about this and RTC is that it runs even if the board si powered off (using the 3V battery)

All your questions are valid, clear and to the point. Thanks for reading the docs before posting questions :slight_smile:

3

Some of the answers are in the chip manual.

  1. I do not remember the exact current values, but the source current was expressed as current/voltage. It was something like 20ma@ 1v and ~4ma@ 3V.
  2. If the bsttery is 3.3G it should be ok.
  3. The cobra comes wit a piezo device installed. It connects to io pin with a330 ohm resistor.check schematic to verify.
  4. Alarm pin… I never checked this out. Again, check the chi manual.
4

Thanks guys for the non-nonsense reply. If only every forum on the net was so good.

I should now be able to design some electronics without frying the FEZ Cobra ;D.

The documentation and samples for the coders are very good indeed. Is there some way we can make the hardware information and design work just as high profile? Perhaps a specific hardware manual or put some summary information on the NETMFProjects website as a hardware sub section to each main area?

Regards

John

5

We are trying to keep it simple, or Freakin’ Easy. So the manual is only 4 pages which has all info you need. If you still need more info then this forum is your manual. Our supports helps you in minutes so thing will delay your progress.

6

Fair enough.

However I can’t see to locate a four page manual for the Cobra! Nearest I see is the 5 page brochure type document. Is it a case of me missing the 4 page user manual?

7

That is what I mean…FEZ is so easy that there is no manual for it, a four page brochure is all you need :smiley:

8

Gus, I have to differ with you. The four page brochure is helpful but it is the ebook that makes it FEZ!

The ebook is one of the best, if not the best, technical document I have ever worked with.

9

I would have to agree the eBook reference makes things much more simple with short concise sample of how to do most things with the mini or domino.

10

Yes but the book is not made for “FEZ” but it is for NETMF in general. So, if you know NETMF then using FEZ is really easy, without the book! This is what I mean :slight_smile:

But, since NETMF is so new and not enough info are on the web, the book becomes a must have.