RGB 7-segment digit multiplexing 3x74HC595

Hi ! i m sorry i m just begining in electronics and i would like to multiplexing this RGB 7-segment RGB 7-Segment Digit - 1 Tall Digit : ID 1399 : $14.95 : Adafruit Industries, Unique & fun DIY electronics and kits 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

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.

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 :slight_smile:

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