Quote:
Originally Posted by Occasionally6
The "joy" of the sketch is that there's not a single "right" way to do it. If you go back a few posts I put up a link to a page from a computer magazine (APC) that was using two 7-segment displays to display a "weather station" output. That has a circuit diagram for the display and Arduino and, most relevant, a downloadable zip file with the sketch that includes how the display is switched. Basically, it sets up an array for each numeral and accesses them as required, assigning them to the pins to perform the switching.
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Found it. Wow! How much of the void update () part to multiplex the display can I just copy and paste? Or do I need to add/subtract any of it?
Quote:
Originally Posted by Occasionally6
The array used is 21 by 7 but some of those are used to display things specific to the weather station. You will need just 10 by 7 i.e. one for each numeral. That does present another means by which you could indicate a negative slope though; set up an eleventh row (11 by 7 array) to flash a "-" in between the numbers.
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I get the part about not using the weather station lines, but not sure what you mean by flashing the negative. Would it just flash a negative really fast before the number displays, like old fashion movie theater adverts?
Quote:
Originally Posted by Occasionally6
A bit. With (your) 10mA per LED segment and all the segments on a digit lit (i.e. with an '8' and dp displayed; the worst case), Ic is: (7+1) x 10mA = 80mA.
With an Hfe of 100, Ib is then: 80mA/100 = 0.8mA.
From the pin that is switching the digit, (5V - 0.7V)/0.8mA = 5375 Ohm = 5.375k Ohm. Use the next resistor value that is larger than that.
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So I used your equation with 20mA, but substituted it for 10mA and got the 5.3k Ohm answer, but somehow missed it (probably sleepy and/or exhausted and/or distracted
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Amazon is going to love me pretty soon, I've got a DMM, all this Arduino stuff, the car needs new struts and now I might be doing an Arduino buzzer project for my work! Woohoo!