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Topic: Controlling 4 7-segment displays (Read 4799 times) previous topic - next topic

0xN35T

Hi everybody. How can I connect 4 7-segment displays to Arduino. Maybe via other chip. Thanks for any help.

Paul__B

Works perfectly for common-cathode displays as the chip implements a BCD to 7-segment decoder.  Up to eight digits (yo code it according to how many).  Requires one resistor to control LED current for all, and a couple of bypass capacitors.

It does not however display HEX characters A to F.  If you need this, or need to use common-anode displays, you code for the patterns yourself.

DatasheetDescription.

Code?  Search on this site.

ngbk1993

http://forum.arduino.cc/index.php?topic=233532.0

this is a 3 7-segment display example. figure out by your own on how to make it to become 4~ ^^

CrossRoads

MA7219 works with common cathode displays.
In No Decode mode, you can make all these letters:
A,b,C,c,D,d,E,F,g,H,h,I,J,L,O,P,S,U, and
0,1,2,3,4,5,6,7,8,9
Decode mode supports 0,1,2,3,4,5,6,7,9,H,E,L,P directly.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Paul__B


MA7219 works with common cathode displays.


Or in No Decode mode, with common anode displays, granted that the code will be more convoluted.

But - it's only code.  That's what microcontrollers are good at!  You code to get around hardware limitations.

PaulRB

Another suggestion for you, 0xN35T, no extra chips required, just 4 NPN transistors and a few resistors:

http://forum.arduino.cc/index.php?topic=188135.0

Paul

CrossRoads

I can't see charlieplexing working when there's 60 digits to control across 15 4-digit displays.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

PaulRB


I can't see charlieplexing working when there's 60 digits to control across 15 4-digit displays.


Me neither, Bob! But why did you even think of it? Did I miss something?

CrossRoads

Here's my vision: 15 shift registers, each sinking current from a 4-digit display, daisychained with SPI.transfer to load them with data.
4 PNP or P-channel MOSFETs, one at a time turned on, to allow one digit from each group to be on.

charlieplexing -thought I saw that mentioned...
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

If one had 4 discrete displays, charlie plexing looks feasible, not so much for a multi-digit display with all segments in parallel.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

PaulRB


Here's my vision: 15 shift registers


Huh? For 4 x 7 segment displays? I'm really confused now. The OP must be utterly baffled.

Is there another thread on this same question, but different requirements?

CrossRoads

Ignore my posts, there is another thread ongoing for 15 x 4x7segment displays.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Nick_Pyner


How can I connect 4 7-segment displays to Arduino. Maybe via other chip.


Yes. I use a 20mm common cathode 4x7 with a MAX7221 multiplexer.

Article is here             http://playground.arduino.cc/Main/MAX72XXHardware

Example is here         http://forum.arduino.cc//index.php?topic=172192.msg1279382#msg1279382

There may be more elegant code around, but it isn't easy to find.

nix_mehr_frei

4 digit common anode displays you can drive with a SAA1064 from NXP (ex Philips).
A lib for this chip can found by google  :)
This is a nice solution via I2C for a panel display with up to 2m cable 4 wire shilded (is use a pice of LAN-cable)
rot ist blau und Plus ist Minus

0xN35T

So for little time I wondered if I can use ATtiny2313 w/ some kind of serial communication like this:
ARDUINO--------ATTINY
DPin1TX -----> DPin0RX
DPin0RX ----> DPin1TX
And if I can connect multiple chips to one serial connection?

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