Custom Keypads

  • Warren Gay


One embedded system hardware device that has not been covered yet is the keypad. Applications for it range from specialized calculators, combination locks, or simple data input keypads. Normally these have their buttons arranged in rows and columns so that they can be scanned by the host computer, reducing the number of I/O ports necessary. You’ll do the same in this chapter but using the DIP form of the PCF8574 I/O chip to avoid using up precious GPIO ports.


Output Port External Circuit Main Program Green Lead File Descriptor 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Warren Gay 2017

Authors and Affiliations

  • Warren Gay
    • 1
  1. 1.St CatharinesCanada

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