what is the limit on how much current arduino units can take? also i notice my keyboard didnt like its cable being laid orthogonal to a 4 pin inductor coil. what should i use to correct this for all connections i use? ferrite rings?
You can pull the 328P data sheet here: you really should keep a copy on your local HD for ready reference. The current per pin and in-total will be documented.
atmega328p
As for the interference issue with the cabled keyboard, I have not heard that one before... But, I use an old notebook myself. I think your keyboard cable is non-shielded and it really should be a shielded cable with the outer sheath grounded to the PC chassis... No different in concept from a microphone cable. I say, if orthogonal offends you - don't do that! Maybe use some duct tape to keep the cord out of your project!
Ray
ok thanks for the ,link its a standard twisted pair connection with that outer foil like layer im guessing it might just be that the back emf the coil produced gave the right frequency of ac to interfere with the key board it was pretty funny it causes the caps lock and num lock led buttons to PWM in sync with the led in the circuit
arduidiot:
ok thanks for the ,link its a standard twisted pair connection with that outer foil like layer im guessing it might just be that the back emf the coil produced gave the right frequency of ac to interfere with the key board it was pretty funny it causes the caps lock and num lock led buttons to PWM in sync with the led in the circuit
My guess is the shield is not properly grounded through to the chassis... Maybe some resistance in the connector. EM energy is funny stuff... Like lightning, you just cannot 2nd guess the stuff!
Ray
what is the limit on how much current arduino units can take
USB port can supply 500mA of 5V current.
Barrel jack may supply upto 800mA if the barrel voltage is low, like 7.5V. Good chance the 5V regulator will overheat and shutdown before getting that much current thru it tho. I was powering 4 MAX7219s from 12V and it was shutting down, dropping to 9V let it run reliably (or maybe 7.5V, I'd have to go see if the supply was still with the display).
nice so what are these eagle boards you have on your sig? the customer can specify a number of digital ins and outs to maximize packing efficiency or ...