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I have just bought an Arduino Lillypad and an MMA8452 accellerometer board and i have few questions:

1) Power supply on lillypad

I know that working with accellerometers is a little bit dangerous: if you plug them to 5v instead of 3.3v you can burn them! So, before to plug and burn anything i want to ask if i have to do something to be sure. In normal Arduino board there are a physical pin to move for having 3.3v (or something that doesn't burn the accellerometer).

2) Physical disposition of resistors

I heave read in MMA8452Q_Example.pde (download here):

SDA and SCL should have external pull-up resistors (to 3.3V). 10k resistors worked for me. They should be on the breakout board.

and i'm thinking about what is the best way to put the resistors on such a tiny boards: i'm not good in soldering and i don't want to ruin the board, and i can't use a breadboard because it is a wearable project. what is the best? using some male pin strip (*)? Or shall i try to cut a little piece of Perfboard and solder over it? And how put the resitors near the accellerometer? or they could be also near arduino lillypad pins?

What can you advice me? I am quite totally new to electronics so any kind of advice or documentations is a valuable help.

(*) male pin strip http://eval.3dpublisher.net/showmodels/TraceParts/Parts/10-05032010-135382/Pictures/10-05032010-135382M.gif

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nkint
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1 Answers1

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The resistors don't have to be on the accelerometer board. As long as you don't intend to make the connection many meters long it doesn't really matter, so they may be as well placed on or near the Lilypad.

Be sure to run the Lilypad at 3.3 V as well. The Lilypad will only pull the lines low, and let the pull-up resistors set the high value, so there won't be 5V on the accelerator's inputs, but the 3.3 V may be too low for the Lilypad's inputs if you run it at 5 V. In most cases it won't be a problem, though. If you can, run the Lilypad at 3.3 V, otherwise have a look at this question to read more about it.

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stevenvh
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