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7 specific volatges to to 1,n,2,3,4,5,6 numbers in Alpha-numeric Display

D

David L. Jones

Jan 1, 1970
0
Going to order the PICAXE, but do I need the 18, 18X or the 18A.

You need one with an ADC, so that the 18X or 18A will work. The 18X has
more memory if you need it.
Also can I feed it the voltage right from the sensor output?

Yes, but use a series resistor and capacitor to ground to filter out
any noise.
Technically the 5.08V input from the sensor could be more than the 5V
rail (which is also the ADC reference), but the ADC will most likely
return a full scale value in this case.
Or do I have to do something special to it so it can read acurrately
and do the approriate action.

Not likely, but...
Your 5V regulator could be anywhere from 4.75V to 5.25V so if you want
to accurately measure those gear voltages you may have to "calibrate"
the ADC by measuring the actual regulator voltage and using that in
your source code as the scale factor.
How much will each gear voltage vary by?
Who ever said that the PICAXE is easy to learn is right. Fairly basic
programming and compiler that come with it are good to.

That's what it's designed for.

Dave :)
 
M

moby

Jan 1, 1970
0
What I am attempting is to take 7 specific voltages, and display
certain numbers for these specific voltages on an alpha-numeric
display.

What I currently have is a resistor ladder that breaks up the voltage.
The resistors form a ladder that breaks up the 5v from a voltage
regulator into reference signals to determine at what voltages an
LM339N will use to ground each corresponding LED. It use 1% resistors
to make sure I get exact reference voltages because in the higher gears
the signal is very close and there is not much gap between voltages.
The output voltages from the sensor are as follows
1st gear = 1.782v
2nd gear = 2.242v
3rd gear = 2.960v
4th gear = 3.630v
5th gear = 4.310v
6th gear = 4.660v
Neutral = 5.000v
The comparators in this circuit will turn on each LED as follows:
1st LED = Anything over 1.022v
2nd LED = Anything over 2.043v
3rd LED = Anything over 2.660v
4th LED = Anything over 3.356v
5th LED = Anything over 4.052v
6th LED = Anything over 4.526v

I now want to take thes voltages and convert them to show the proper
gear on an alpha-numeric display.

How can I turn what I have working in to alpha numeric?

Or, Do I have to start a whole new circuit. Something that takes the
voltage and turns it into a digital signal and then sends to an A/N LED
display.

Here is something that might set you going in the right direction if
you decide to use a pic.
http://homepages.kcbbs.gen.nz/moby/atod.asm
this particular widget is a flying spot VU meter using 12 LEDs across 4
port pins of
an 8 pin pic and the onboard a to d converter, but by rejigging the
breakpoints to your voltages (V/5*256) and using different bit patterns
on 7 output lines of a 14 pin pic the job would be done. Oh yes you can
get plenty bright enough 7 seg displays to be daylight readable...or
you could go retro and use a numitron (but you would need something
like a ULN2003 as the little pic doesn't have enough output grunt).
M
 
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