Arduino Memory Buttons

A project made with Arduino to redesign a control panel with large and mechanical on-off switches. A circuit was designed with Arduino to use a smaller push-release button. The pressed buttons are kept in memory and when the power is given again, the output of the previously pressed buttons does not change.

The circuit works without modification with Arduino Nano, Arduino Uno or Arduino Pro Mini.

MCP23017 multiplexer integrated circuit was used to multiplex the output of the Arduino module and drive LEDs, relays etc. 74HC595 was not used because there were problems in previous projects.

According to past experiences, 24C02 eeprom is used against the possibility of failure or locking due to frequent writing and erasing of the Arduino memory. In addition, there is a simpler version of the Arduino circuit without eeprom.

External libraries used for MCP23017 and 24C01/02 EEPROM should be in the project’s working folder. Instead of Arduino modules, ATMEGA8, ATMEGA168, ATMEGA328 microcontroller ICs can be used.

Observed disadvantages: Every time the supply voltage is started, before control is given by the Arduino, the MCP23017 IC brings all outputs to “0” for a very short time (can be seen as a flash of all outputs in the video). This is not a problem with the device used, but it is something to keep in mind. The version without external Eeprom does not have this problem.

Arduino Memory Button Circuit Diagrams

source: kn34pc.com/construct/lz2wsg_arduino_tactile_sw.html