i'm exploring options for a project of mine i'm building custom led tail lights for my 1973 dodge charger and was wondering how many 2.2V 20 mA led's can be powered by each output, can the board be powered and controlled by two different power inputs, and can the inputs and outputs be controlled independently and simultaneously?
the way the wiring works on my car is there is to wires leading to the taillights that control the brakes and turn signals when both are on the brakes are on, the turn switch the takes over either one, one at a time and routes the power thru the flasher.
You can safely draw 40ma from each arduino pin. But, AFAIK you should not exceed 200ma total. So, two per pin or 10 total. You can use two different power supplies but the board only wants to see one at a time. I/O can be done independently and at the same time.
damn i was hopin for more i'll just have to incorperate relays into my design and maybe have the arduino control them i can use two diodes and a single reg for the power supply that should cover that part now what would be best to connect the cars original wiring to, the analog I/O's? when all said and done i might have nothing short of a message board for taillights ;D
The original car wiring is almost certainly 12V which you cannot directly hook up to the arduino. You can use a voltage divider to cut down to 5V. If you want the arduino to know when power is going through a 12V wire your choices are: Voltage divider or relay. That is, you can use a relay which is actuated by the 12V and then passes a 5V signal to the arduino pin.
ah i c well one more question before i go any further once the program is loaded is it there permanently because i do not want to have a dead battery in the mornin LOL and as soon as the board is powered up does it run the program, i wanted to use the brake and turn signal wiring as the power supply i can use regulators and diodes and split the power to the supply and the inputs. how well do u think that would work?
It almost sounded like AdderD was saying you can't put a car's 12VDC accessory directly into the Arduino. The Arduino platform has a voltage regulator built in. For the Arduino Duemilanove, the rated input range is 7VDC to 12VDC preferred, 6 to 20VDC limit. I'd be slightly leery of the horribly noisy power source, but a suitable capacitor across VIN and GND should help.
As for working with 12V accessories or signals to the I/O pins, you will need to do some level-adjustments, as the I/O pins can't exceed 5VDC. There are suitable transistor techniques to do inputs and outputs appropriately, but that does increase the complexity of what you're trying to do.
Yeah, sorry if I wasn't clear. I was talking about inputting to the I/O pins. You certainly can't put 12V right to an input pin, you need a voltage divider or a relay. But you can put 12V right to the power input of the arduino.
ok so 12v to the power input is ok but not the analog inputs? and will a noisy power source cause problems i just need to run LEDs, as far as regs go it's not really a problem i plan on having it in and enclosure though how will that work for heat dissapation. please excuse all the questions i am new to electronics and am learning as i go. one more thing i think u can but want to be clear can input from the analog I/O be programed to control the digital I/O? the more output controlers i have the more elaborate i can get with the lighting sequences.
Up to 12V power input.
5V analog or digital inputs.
5V digital outputs.
Input pins can be read, and then your sketch code can make any decisions it wants, and put whatever it wants on output pins.
I suggest you work through a couple of the examples and tutorials, it will help you to build a lot of confidence in the system, and show where you'll have to work out something more complicated, such as providing additional current and voltage for driving many LEDs at once.
i think i have to use either relays or transistors because i need to power hundreds of leds per tail light maybe a thousand total when the brakes are on so i was gonna have the cars wiring power everything just split it off and regulate it where i need it
new and better idea instead of wiring sOOOOOOOO many leds i'm using 4, 8 point stars with a total of 33 leds per star much easier only 132 to wire instead of 500
O O O
O O O
O O O
OOO
OOOOOOOOO
OOO
O O O
O O O
O O O
new question how long from turning power on to the board does it start running the program?
If you keep the bootloader, then it takes about 5 seconds. If you upload the generated hex through the ICSP header, it starts instantly.
thats what i was hopin for i plan on uploading it to the board then mounting the board in an enclosure so once the brakes are hit or the turn signals are activated the board will have power and start working
I think the board could/should be powered on constantly. When you hit the brakes, it starts doing what you want. That is how I would do it.
i think if it comes to it that would be ideal have keyed power but i want to keep this as simple as possible, possibly something i could do for friends they can just plug in