Thanks again,
just to be sure, is this circuit right?
and im really really sorry for bothering you with such foolish questions but I still did not understand how to supply my arduino. I mean you have these arduino ports:
You have to draw that schematic better. It looks like A0 is connected to Vcc and that the plus of the battery is connected to the plus of the Arduino. So it needs to me cleare what is connected to what. To supply your Arduino with an external supply connect the gnd to the supply negative and the 5V regulated supply positVe to the 5V pin.
Grumpy_Mike: You have to draw that schematic better.
I hope this is better:
The red marked wires are + blue -
The expander pins A0,A1,A2 define the I2C adress, otherwise I could give them input with another 5V supply from the arduino (if thats possible)
And just to be 100% sure to connect the supply to the right arduino port, you mean this one:
Edit: Im still wondering if 2.5A is ok for my project because: 1 LED 21mA 42*21mA=0.882A 0.882A+Arduino current is still about 1 A I think, so does it matter that I have like 1.5A too much or do I need that much current?
Grumpy_Mike: it does no harm having a power supply that is capable of more current than you need. It is often a good idea to to run them at only 80% full capacity.
in my case it would be like 40% of full capacity is that ok?
The only thing missing from that diagram now is the 0.1uF ceramic capacitor between the Vdd and Vss pins on each expander chip, and the missing 4K7 resistors pulling up the I2C lines.
in my case it would be like 40% of full capacity is that ok?
Even better.
And just to be 100% sure to connect the supply to the right arduino port, you mean this one:
Yes. I would disconnect the external circuit and the external power supply when you are uploading code and then reconnect it when you have removed the USB connection.
Grumpy_Mike: The only thing missing from that diagram now is the 0.1uF ceramic capacitor between the Vdd and Vss pins on each expander chip, and the missing 4K7 resistors pulling up the I2C lines.
Im a bit confused now, can you explain me what these components do? Furthermore:
Grumpy_Mike: 0.1uF ceramic capacitor between the Vdd and Vss pins on each expander chip
what do you mean with between, I was thinking there are 2 different wires, should I connect them with these Capacitors?
what do you mean with between,
One end of the capacitor to the Vdd and the other end of the capacitor to Vss. It is decoupling and is not an option it is essential. See:- http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html
can you explain me what these components do?
I2C works by the chips pulling down the signal wires. The resistors pull up the line when no chips are pulling them down. The Arduino does enable the internal pull up resistors on these two lines but they are no where close to being low enough. Without them the signals are severely degraded. Again this is not an option but a must do. See:- http://www.dsscircuits.com/index.php/articles/47-effects-of-varying-i2c-pull-up-resistors
Thank you so much for your advice,
as far as I understood, I need 2 4k7 ohm resistors at the beginning of the SDA and SCL line and 8 0.1uF ceramic capacitor, right?
Right. The resistors can be fitted anywhere, from the signal line to +5V, the position doesn't matter.
I’ve got 2 questions left:
can I use the capacitors in a breadboard like this (imagine the resistor would be a capacitor):
Do I have to care about the rating of a capacitor, because this one has a rating of 50V
and I would use this to connect my adapter with the circuit. But Im wondering what is + and - there, and can I just put the - straight into the ground of this component?
A little question I have as well is wether I need adjust my arduino for the power supply at the 5V pin.
Yes you can put components directly into the bread board like that. For the capacitor cut the leads short.
Yes you could use that board if you get a lead that delivers power like that. I think normally it is the type B that receives power not the type A
No preparation is needed to drive the Arduino with the +5V line.
@jakub014, Why are you doing this ? Is this a school project ? Based on the schematics you posted and the questions you asked, you have little experience with electronics. Are you a hobbyist or electronics student ?
@raschemmel Unfortunately my IT teachers came up with the idea to make an arduino project over some months. We barely had any experience about electronic and arduino at the beginning. Additionally our teachers just gave us 2 lessons about electronics and 8 about arduino basics in general. So, Im apologizing for beeing such a difficult case, I thought it would be easier to control some LEDs.
@Grumpy_Mike
Grumpy_Mike: I think normally it is the type B that receives power not the type A
Is that a problem? If yes, would you recommend me a board that fits in my project? (perhaps from here, cause Im ordering most of the things there.)
USB-A is the flat one that plugs in a computer.
USB-B is the other end that plugs in a printer (or an arduino).
That adaptor would have to be the 5V source, because the other end would plug into the arduino and provide 5V to the arduino.
Is that what you are asking ?
raschemmel: Is that what you are asking ?
Yes kind of, I meant wether this component would be fitting or not, but I think your answer expects this already, so my question would be solved. Im still wondering what the ports of this board (VCC, GND, ID, D- and D+) are or which of them I need. the board
Im still wondering what the ports of this board (VCC, GND, ID, D- and D+) are or which of them I need
You need just VCC, and GND to power your system.
I would advise against that micro connector. In my experience with the Raspberry Pi, these coupled with the lead often have a high resistance. As you are driving a high-ish current through them this can lead to an unacceptable voltage loss. Best go for the full size connectors.
No. Look at the USB socket that is on your Arduino. Use that type.
Ok I got 2 final questions: 1. I dont find any full size USB B breakouts, just micro or mini.... 2. Im not sure what 0.1uF cermaic capacitor I need because they have always high voltage data. Can you show me one, which is suitable for this project?
