The TR-909 clone firmware I’m currently developing writes sequence patterns to eeprom. The avr-libc library provides eeprom writing function, but it is synchronous.

https://www.nongnu.org/avr-libc/user-manual/group__avr__eeprom.html

However, many of the real-time processing in the firmware are done without interrupts, then these processes stall during the slow (synchronous) function. So I decided to develop the asynchronous version of eeprom writing function by my own.

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