# ADC to 3 digit 7 segment highest value needed is 360

Discussion in 'The Projects Forum' started by Kringjat, Jan 15, 2008.

1. ### Kringjat Thread Starter New Member

Jan 15, 2008
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0
hey guys i am new here so if I am doing something wrong tell me

i have and ADC 8 bit and i need to display it on a three 7 segment but my problem is that the highest value must me 360 How can i do it? a pic is needed? if if yes how i can do it THKS

2. ### beenthere Retired Moderator

Apr 20, 2004
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We do not have enough details to give an intelligent answer.

An 8 bit A to D converter has only 256 states - 0 to 255 - so a value of 360 cannot be output by the device. If, however, you are using the conversion as what amounts to a voltmeter, then an inexpensive digital panel meter will work.

3. ### Kringjat Thread Starter New Member

Jan 15, 2008
4
0
so if a bigger ADC is used how can for example 9 bit having 512 how it can be done to display values of 0 to 360

4. ### Ron H AAC Fanatic!

Apr 14, 2005
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You could use a microcontroller, and have the software convert all numbers greater than 360 to 360, or you could use an EEPROM which you can program to do the same thing.

5. ### Ron H AAC Fanatic!

Apr 14, 2005
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You could scale 0-255 to read 0-360, but some numbers would be missing.

6. ### SgtWookie Expert

Jul 17, 2007
22,183
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Here's an article that explains connecting 7-segment displays to a PIC microcontroller:
http://www.picbasic.com/resources/articles/ledart.htm

A number of PICs have built-in ADC's. You'll need to do some research to figure the rest of it out.

A microcontroller such as a PIC will very likely be your lowest-cost solution with a minimal parts count.

7. ### scubasteve_911 Senior Member

Dec 27, 2007
1,202
1
The standard methods to display the data would be either scale the analog voltage appropriately, or to scrap the resolution from the ADC.

So, if you're ADC accepts 0-5V, then make sure the signal doesn't go past ~3.5V. Otherwise, create a lookup table. Use excel to make a 0-360 range over 0-511 rows. Copy and paste it into your PIC compiler, then reference the table.

Steve

8. ### beenthere Retired Moderator

Apr 20, 2004
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Not to be too persistent, but I would be curious to know what is being measured? I am not sure any answer is correct without knowing what is going on.

9. ### lightingman Senior Member

Apr 19, 2007
374
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Hi.... A PIC is the best solution... It will do the A/D conversion and multiplexing of the LED displays... What sort of sample rate are you looking for, and what input voltage range...I may be able to help you...Daniel.

10. ### SgtWookie Expert

Jul 17, 2007
22,183
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Just a guess - but there are 360 degrees in a circle, or points in a compass...

11. ### lightingman Senior Member

Apr 19, 2007
374
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Yes, but what voltage range into the A/D is required to read 0 to 360....Daniel.

12. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
That sounds like a good guess. Then the question is the resolution required. If he needs to indicated all 360 deg., then the A to D resolution will have to be at least 10 bits.

13. ### lightingman Senior Member

Apr 19, 2007
374
22
Yep !...The PIC will do that as they have 10 bit A to D's on board...Daniel.

14. ### Ron H AAC Fanatic!

Apr 14, 2005
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Wouldn't that be 9 bits minimum? I don't think you can but a 9 bit A/D, so this is an academic question.

15. ### lightingman Senior Member

Apr 19, 2007
374
22
Yeh....8 bit's = 255 + 0, 9 bits = 511 + 0 and 10 bit's = 1023 + 0....The A to D converter in th ePIC is software selectable for 8 or 10 bit's resolution...Daniel.

16. ### Kringjat Thread Starter New Member

Jan 15, 2008
4
0
Hey guys thks for the feedback till now and sorry for missing some infor ans for your infor yes its is for a compass my problem is to having a voltage and needs it to be converted to 360 degrees but is it possible to not use a pic because that what i wish to do having an adc to 3 7 segment display displaying 360 degrees as the highest value any ideas thks

17. ### Ron H AAC Fanatic!

Apr 14, 2005
7,050
657
A couple of questions:
1) How do you plan to convert from binary to BCD?
2) Don't you actually want to limit the highest number to 359?

18. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
How are you planning to generate the analog voltage? Will you use a servo potentiometer?

If you have some way to make a voltage that follows the compass rotation, you can scale it and use a panel meter. The meter uses A to D conversion to get the numbers to display.

19. ### lightingman Senior Member

Apr 19, 2007
374
22
Hi again....I did this last night.... 0 to +5v, reading 0 to 360 with a PIC and a 4511 multiplexed onto 3 LED displays.... The voltage can be scaled to any value between 0 and whatever....Daniel.