Shift Register / CD4511 combo

hi all,

first post...

for reason, i'm obsessed lowering amount of pins i'm using run 4 digits 7 segments led display common anode (or cathode). came conceptual idea of using 595 shift register feed cd4511 decoder.

the shift register feed 4 bit (bcd) cd4511 - connected led display - , 4 bit common anode or cathode close circuit. multiplex like:

bcd  - 4 cathodes
0001   0001  (writes 1 on digit 1)
0001   0010  (writes 1 on digit 2)
0001   0100  (writes 1 on digit 3)
0001   1000  (writes 1 on digit 4)

this allow daisy chain add displays without increasing number of pin used.

my first assumption there either better way or not work but, i'd understand how or why,

thanks input,

hi , welcome.

yes in theory work, display have dim avoid overloading '595. each '595 output source/sink around 20ma, which, shared among 8 segments , 4 digits, 20/32 = 0.6ma each!

for learning purposes, interesting question, in practice use max7219. drive 8 digits (brightly) 3 arduino pins. or saa1064 drive 4 digits 2 lines (i2c). or one of these 1 line!

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