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Topic: RGB 7-segment digit multiplexing 3x74HC595 (Read 388 times) previous topic - next topic

samellouze

Hi ! i m sorry i m just begining in electronics and i would like to multiplexing this RGB 7-segment http://www.adafruit.com/products/1399 with 3x74HC595 could you help me with wiring please ? i have to chain together 3 74HC595 to control 24 pins with a 3 pin SPI interface ? Thank you very much

CrossRoads

With 3 HC595 you are not multiplexing, just sending out 3 bytes of data.

Connect SCK to SRCLK of each device.
Connect SS to RCLK of each device.
Connect MOSI to SER In of first device,  Q7 of 2nd to Ser In of 3rd.
OE/ of all three to a PWM pin for brightness control, or to Gnd.
MRCLR of all 3 to +5.
Connect 0.1uF cap from Vcc pin of each to Gnd.
Don't forget current limit resistor for EACH LED, sized appropriately:
(5V - Vf)/.02 = lowest resistor value, higher is ok.

May have to tweak value so that perceived brightness between colors is the same.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

samellouze

#2
Apr 14, 2014, 07:58 pm Last Edit: Apr 25, 2014, 08:48 pm by samellouze Reason: 1
Thank you ! and sorry for using wrong terms ...
Just to be sure here is my electronical scheme is it right ? and could you please give me a test code to make it run i tested this one http://arduino.cc/en/Tutorial/ShftOut21 it work but i don't know really how to control it. Thanks for your help  :)





CrossRoads

We can't all open the dl.free.dl link.
Modify your post, click Additional Options, Browse to your locally stored image, and Attach it.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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