Hello Gents,
I would like to have your guidance please. My target is to build a display which contains 2 digits 7 segments and single digit 7 segment but it should be like this format :
00 00 1 00 00
so 4 x 2digits and 1 x 1digit
so to save pins on arduino, i am looking to build and program this using I2C. My question is can you help me with info on which IC i must use and maybe links on tutorials for this from arduino forum or any other websites ?
thanks in advance 
Why not just use the readily available cascadeable modules using MAX7219s?
Put two together and blank out (simply do not activate) the digits you do not want.
Paul__B:
Why not just use the readily available cascadeable modules using MAX7219s?
Put two together and blank out (simply do not activate) the digits you do not want.
Thanks Paul for your reply,
the reason is that i want a custom made with smaller 2 digits than the single digit display. I have built one before using the MAX7219 but i need to save pins on arduino and MAX7219 with other components consumed the pins and nothing left and i need to add more features.
My Circuit will contain 13 LEDs and 4 2digits display and 1 single digit display, the MAX is SPI as i recall so I want to try to save pins with I2C if possible. My display is similar to the below in the picture
runaway_pancake:
Arduino Playground - I2CPortExpander8574
hello Runaway Pancake, thank you for your reply
well that is interesting but my application would need more Analog pins and more PWM pins because it will have potentiometers connected to the arduino, pushbuttons and rotary switches (12positions x 4) so for the rotary switches i will have IC shiftin and for the LEDs shiftout registers. The problem that would prevent me from using an expander is that i will have a cable of 12 cores connected to the pcb containing the shift registers and the max which will be connected in a dash where the arduino is contained ! the maximum wires possibility i have is 12 core from which 2 are for +V and Gnd
jackrobot:
Try to search on digikey.
but i must have specific IC in mind to search for it no ?
Ht16k33! This chip can drive your displays and your individual LEDs, and also scan your pushbuttons.
Are the displays common anode or common cathode ?
Some driver chips can sink only, eg pcf8574, so are suitable only for a common anode device.
6v6gt:
Are the displays common anode or common cathode ?
Some driver chips can sink only, eg pcf8574, so are suitable only for a common anode device.
I can't really tell because the display i did 3 years ago but i am trying to make it better maybe
PaulRB:
Ht16k33! This chip can drive your displays and your individual LEDs, and also scan your pushbuttons.
PaulRB thank you so much i'll give it a try ! 
Found on aliexpress and very cheap !
Found this tutorial seems not bad ! Controlling an LED Matrix with the HT16K33 - Parts Not Included
