First Project

Projects General Guidance
1

Hello, I recently got an arduino along with the elegoo super starter kit and the Make Arduino book. I was hoping to teach myself electronics and programming along the way. After reading most of the book I decided on trying my first project. I quickly discovered I still have no idea what I'm doing.

So here is my project goal: build and program an instrument package for a high altitude balloon and have the data put onto an sd card to be exported to Excel.

I so far have the dht11 temp and humidity sensor and the sd card read/writer.

My questions include:
I have the sd card plugged into the 5v power. How do I power the dht11 and if I want to add more sensors in the future how should I power them?
Secondly I have the basic knowledge from the book but no idea where to start to write code for data logging. Any help is appreciated.

I hope to be able to include my local CAP unit as a fun sort of science/astrology/search exercise and will keep all of you updated if you wish. Thanks.

2

Start slower. A balloon recording package is not a trivial exercise! The IDE has quite a few examples, of increasing complexity, built right in. After you do a few of those, you will understand how to program it to do the things you ultimately want it to do.

3

And start by writing short programs to learn how to use each of your external devices on its own. Don't try to build a composite program until you can do all the parts separately.

...R
Planning and Implementing a Program
Arduino Useful Links

4

DWChiver,

Nice that you got a book and a starter kit for the arduino. Your first project is however a bit too ambitious.

But let's see.

You can power most sensors (as long as they are standardized) with an arduino with 5 V (There is a version of the pro mini, that runs at 3.3 V). Make however sure that the Instensity of the current is enough, as the arduino Uno for example offers 40 mA on each pins. Conclusion: You need to calculate, the current coming to the arduino, the current left and used by the sensors, therefore it would be wise to get a multimeter too.

5

With "plug the SD card to the 5V" i understand what you now meant.

  1. The arduino Uno has 2 5V Power Output
  2. If the Intensity of the devices you want to connect to the 5V pin is not higher than 40 mA, connect many cable to the 5V pin.
  3. You can always turn any other pin to a 5V power output. Just use
digitalWrite(digitalPin, HIGH);
6

AKJ:
If the Intensity of the devices you want to connect to the 5V pin is not higher than 40 mA, connect many cable to the 5V pin.

You can always turn any other pin to a 5V power output.

The 5volt pin is the power rail of the Arduino (5volt Arduinos).
It has nothing to do with the 40mA absolute max limitation of an I/O pin.
You can e.g. draw ~450mA from the 5volt pin(s) of an Uno when powered from USB.

Not a good idea to power things from an I/O pin, unless they draw very little current (<=20mA).
Note that there can be some volt drop when doing so (not the full 5volt).
Leo..