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PSoC 5, 3 & 1 MCU

Len_CONSULTRON
Honored Contributor II

To all,

A question was asked on an earlier form post about supporting more than 8 digits on a 7-segment LED display.

Post: LED-Driver-with-10-commons-how-it-is-possible 

It is possible to support up to 24 digits with with the Cypress/Infineon LED Segment and Matrix Driver (V1.10).

Using this driver, there are only up to 8 commons supported.  To use this driver for more than 8 digits you need to allocate more segments per common.  This is referred to on pages 30 and 31 of the datasheet.

For example to allocate 24 digits of 7-segments (really 8-segments) you need to do the following in the configuration for 8 commons and 24 segments.  If you need 16 digits you can allocate 8 commons and 16 segments.   For 15 digits, 5 commons and 24 segments.

In other words, let's say you need 'x' digits.   Then you need a minimum of 'y' commons.   ROUNDUP(y = x/3)

segments 0-7 are used for the first set of digits (1 to x/y) and segments 8-15 for the next set ((x/y)+1 to 2x/y) and (if needed) segments 16-23 for the last set ((2x/y)+1 to x).

Each digit can be accessed in the API calls using the "position" variable.

The downside of sharing commons across digits is that it requires more current to be sourced or sunk.  This can be achieved by using external components such as NPN and PNP transistors.

As a parting note:  I have provided a new LED matrix driver component that can allocate up to 16 commons.  This is a functional extension of the Cypress component.   This component allows for separate commons drive for up to 16 digits if you need it.  Additionally in a similar manner this new component can handle up to 48 7-segment digits.

The new component can be found at: Code-Examples/New-LED-Matrix-Driver-Component-Max-24-Segments-and-Max-16-Commons 

Len
"Engineering is an Art. The Art of Compromise."
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Hari
Moderator
Moderator

Hi Len, 

 

Thank you for sharing the custom component and for the explanation! This would definitely help the customers and thanks for your interest in our products 🙂 

 

Best regards, 
Hari

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