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avidflyer
Posts: 138
Hello,

after I got the Information, that the Mega drive LED directly over the Main Chip, I think Iam linited to max 8-10 LED with 20mA. (Chip can handle 200mA)

So now I am asking myself:

How many Stepper (28BY... with ULN 2003) I can drive with one Mega?

Therotical there are enough PINs for 12 (48Pins) but how many Amps will get the ULN Board per PIN?
I drive the Motors with a external power supply.
:confused:
And how many 7 Segment can I daisy chain? or In total will drive a Mega?

Thanks for answering

Christian
2017-01-23 18:49
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pizman82
From: ETSI, Germany
Posts: 6010
Supporter
http://www.mobiflight.de/faq.html

There is shown the maximum of every device (Limit by Mobiflight)

We talk about 200mA Limit in other thread..... Not shure but i read a little bit in the Web but not realy found lots of infos....

Maby we should think about if the Limit is just a "reference" ....
If we use 500mA over hours will be a problem.... but for some seconds ???

So 10 LED reach the 200mA Limit like the other user suscribe..... But how often are 10 of our 40 conected LED Light up the same time ??
Or how often work ALL 10 Stepper Motors in same moment ??
And if we override the Limit..... Is it realy a problem, when we do this only for some seconds or minutes and not all the time ??
Good Luck !
2017-01-23 22:00
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tommy1332
Posts: 26
The datasheet of the ULN 2003 says it draws about 1mA input current (per pin).
So you don't have to worry about using too many steppers if your power supply can handle the current the motor draws (much more than the 1mA).

For your other question pizman82 already posted the address to the faq.
The relevant part is
iconQuote:

That's theoretically 256 7 segment digits. 4 Modules connceted directly to the MobiFlight Board supporting a chain of 8 modules with 8 digits each. 4 x 8 chained modules x 8 digits = 256 digits. Currently the firmware limits to these 4 which use 12 pins at the Arduino Mega board. For each module you can create a chained setup of 8 modules in a row. Each module is able to drive 8 digits.

2017-01-24 22:25
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