Hello,
I am new to Arduino so this might sound silly to those of you that are more expert...
I am trying to operate Bodet electromagnetic 7-segment display. I know that the module require 280mha 12V for .25 of a second to flip one stip and I know the wire configuration on the display unit. what I don't know is how to tell the Arduino to change the display. I mean, is it possible to drive 12V though the Arduino (I have Arduino Mega) and how exactly do I tell it to do so? if I want to use a different GND to each display unit how do I change it in the programing?
I hope I explained myself clear enough... :-?
Not directly, but there are lots of examples available of people using chips like th ULN2003 to drive relays, solenoids, and other devices that are similar to your display.
It's preferable, if you can, to leave the positive side of the display connected, and switch the ground side: the circuits for switching ground are cheaper and simpler than the ones for switching the positive supply.
The display unit is a common-anode. so the I guess that this is what you meant.
the way this unit work is like that. you have 14 pin cable running though all the display units ( in my case 4 ), every time you send down that wire ON of OFF for each segment, than change the anode active and that way control which digit changes.
I just cant figure out how to do this efficiently as possible without using a lot of relays...
Interestingly, these do: there are series diodes built into the modules (perhaps so they can be powered from AC while maintaining the polarity of the magnetic field??).
The manufacturer's site doesn't have any datasheets, and the extremely limited info in the one info sheet google turned up doesn't have any data on voltage or current requirements. So it's not possible to offer advice with a whole lot of certainty on how to wire them up.
But, assuming the figures that garfield got from some unidentified source are correct, something like the ULN2003 (but not the ULN2003, itself, due to the total current sink limitations for the chip) seems like the way to go for driving the low side, with a P-channel FET for the high side of each digit. Then you'd wire it up rather like the driver for a multiplexed 14-segment LED display: a couple of shift registers for the segment data, and a ULN2003 (perhaps with another shift register, depending on the number of digits) to drive the gates on the high-side FETs.
What's a good replacement for the ULN2003 (preferably with FET drivers) that can handle 2A per package?
I got my information from EPE magazine from 2002, John Becker wrote about them. that is where i got my information.
my current problem is with defining pins. I want the dedicate 14 pins as "+" positive, they all will run though the four digits, and 4 pins as "-" that will allow me to control which digit will respond to the "+" signals.
any ideas?