4.2.1.1 Storing Digital Sound as Raw Data on an SD Card

The process defined above is used with one of the accompanying example projects provided to store a digitally recorded signal externally to the AVR device. This enables a device with limited memory such as the ATtiny817 to perform data collection on a scale not possible with its internal memory. The described Start, Continue, and Stop functions for both read and write are used in the record and playback functions. Using the SD card in SPI mode enables the data to be read and written at a rate defined by the SPI clock and at intervals defined by how fast the end of the current buffer is reached.