Hello,
I want to make a digital price board using 1 inch 7-segment display and Arduino nano.
There are 10 lines of 5 7-segment displays. The total number of 7-segment displays is 50.
Using MAX7221 ic we can connect only 8 displays.
Please suggest any other option to connect 50 displays to Arduino.
You didn't say how many digits per display. Can you clarify the layout of your price board?
So, you mean "5 digit" 7 segment displays? What do you mean "10 lines"? How many displays in a "line"? It is to understand these questions, that I asked for a layout. You didn't provide one, or make it clear verbally.
I think you might mean, ten 5 digit displays mounted vertically. So a total of 50 individual digits. Can you confirm?
Please supply a link to the display modules you plan to use. Also are they common anode or cathode? Are you planning to design your own display modules that incorporate an LED display controller IC, or are you planning to buy those ready made? What components have you found already that you think you can use?
What Arduino do you have?
Use 10 of those chips, one per line. You will need one pin for each to act as an SPI "Chip Select".
You cascade seven pieces of MAX7221/MAX7219 chips and operate 5x10 7-segment display unit. Here is an example of cascading two MAX7219s.
All displays on the same large PCB?
No.
Small PCB for each 5 digits and connect together
No, they can be cascaded and share the same Chip Select/Latch pin, as described by @GolamMostafa .
An alternative to max7219/7221 could be ht16k33. Each of these chips can drive 16 x 7-seg displays. You could have a chip for 3 lines of 5 digits, so you would need 4 chips in total.
Most chips for driving 7-segment displays work best with common cathode. Can you buy the CC version of that display?
The seller's page is missing important information, such as the forward voltage and maximum current of the segments, and a link to a data sheet. I would not buy from this seller.
You're right. I missed the DOUT pin because the datasheet doesn't show it in the "Typical Application Circuit".
https://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf
CC-type 7segment display devices are also also well suited with MAX7219/MAX7221 IC.
Yes, the chip was designed for CC displays. Did you mean to say CA? CA displays would also work with max7219/21, but a few of the chip's features would not be available.
It is here in page 13 of the datasheets that you have attached.
