The Parrot field engagement board demonstrates the capabilities of the ATtiny817 with audio processing, using its ADC and DAC peripherals. It is possible to record, playback, erase, rewind, and fast forward by using the buttons.
As shown in the figure above, once the “REC” (record) button is pressed, the electret microphone starts to detect an analog sound signal. The sound signal will be processed in the front-end operation amplifier and a low-pass filter will be applied to the signal. The signal will then be digitized by the ADC of the ATtiny817 microcontroller. The converted sound data is stored in the external data Flash through the SPI interface. When the button is pressed again, this recording process is stopped.
Once the “PLAY/STOP” button is pressed, the sound data stored in the data Flash is read and converted to an analog signal through the DAC on the MCU. The analog signal is then sent through a low-pass filter before it is sent to the amplifier with the set volume. This allows the user to listen to the previously recorded sound. If the button is pressed again, the play process is stopped.
The board is supplied with +5V from the Micro-USB interface with ESD protection. The applied LDO can source out 150mA @ 3.3V system power.
