GPRS to Arduino - Where is the "VDD"?

Using Arduino Microcontrollers
1

The GRPS has a 5V pin and a VDD. The 5V obviously goes to the 5V, so should the VDD go to the 3.3V?

Also, the GPRS has 2 "GND" pins, one next to the 5V pin and one next to the "RST" pin at the bottom which I'm guessing is reset.

I'll upload a picture, but I'm not sure which GND Goes to which, etc.

Thanks.

http://i.imgur.com/En5717F.jpg - Arduino (There is the GND Pin at the top right below "AREF" - Light...)

http://i.imgur.com/UcSPdN0.jpg - GPRS

2

The grounds must be connected. All the ground pins on the Arduino board are connected to eachother, so it doesn't matter which Gnd pin you connect to the other device's Gnd.

As for the Vdd pin, you'll have to consult the documentation for the GPRS board and determine why there's a 5v and a Vdd pin, and how they should be used to interface with a 5v microcontroller. My guess is 5v is connected to 5v, and Vdd is not connected (being supplied by an on-board regulator), but you should double-check that.

3

Okay thanks, Is there any harm in connecting the 5v to 5v and the VDD to the 3.3V?

4

stormx:
Okay thanks, Is there any harm in connecting the 5v to 5v and the VDD to the 3.3V?

Yes, likely to be harm. Next to no chance the GPRS takes 2 different voltage inputs. My guess is that VDD is an output from a 3V3 regulator on the GPS board.

Actually, from that (blurry) picture, it doesn't even look like there is a pin to connect to on VDD.

My other though is that there might be several devices on this board. It might run on 5V, but other stuff on it might run at a different voltage. But impossible to tell with the limited information given.

Find the datasheet. Don't guess.

5

I see, the VDD pin can be connected easily...

So, what more information do you need?

The project I am doing is this:

EDIT: The datasheet i believe http://stak.com//image/data/products/242/242584/sim800-gsm-3.pdf

6

The datasheet isn't what you need. You need documentation for the board, because different manufacturers will put different auxiliary components on their board, and it's those parts that are relevant here.

7

Okay, How do I find this?

Surely, now that I know what to connect to what... It's all plain sailing?

What do i need from what you are suggesting.

Thanks a lot..

8

If it was a chip, VDD is probably used to supply the i/o to select 3.3 or 5 V logic.

9

stormx:
Okay, How do I find this?

Surely, now that I know what to connect to what... It's all plain sailing?

What do i need from what you are suggesting.

Thanks a lot..

Go to whoever you bought the board from. DrAzzy is right, I mis-typed, you need the board documentation, it will tell you what to hook up to what. Which you don't know 100% right now, unless it is buried somewhere in that 300 page document you linked (which appears to be a command specification document, which will be helpful for coding, but does not appear to give wiring info. At least, not that a quick look turned up, I'm not reading through 300 pages for your project).

10

Yes, sure, I've watched a few videos and heard someone say that it converts it to 3.3v? I plugged it in at a guess and it powers on, etc... Not sure if that's doing any damage.

Thanks, the seller has said they can't help for 5 days... As it's china's national week or something lol.