![]() ![]() At 4Mbps the SPI speed is indeed superior to the 64kbps needed for real-time audio replay. Is based on the assumption that the feed rate is few times bigger than the consumption rate. STM32F103C8 and ATmega328 - SPI communication setup The trick here is to feed data to uC 2 so that it'll never choke or starve. ![]() The ATmega328 consumes data at a constant rate and the STM32 provides it. The ATmega328, uC 2, will be the slave in this tandem for obvious reasons: low memory, low clock frequency, whilst the STM32, uC 1, will lead the communication. Being natively equipped with SPI, both the ATmega328 and STM32F103C8 controllers are the subjects of this post. High transfer speeds can be achieved by the use of SPI transactions. Let's plow ahead with the idea of an independent device needing real-time data - to be processed or replayed - in the lines of ATmega328 Audio Controller. Combining more than just one PWM output for audio generation has clear advantages but this article is not about that. All is not lost though for the ATmega328. Although a sine wave has enough energy concentrated in a single frequency spot to achieve high SNR values, something as diverse as the audio signal simply hasn't. Besides, eliminating undesired components from the low resolution pulse width modulation spectrum is a pain for the passive first order low-pass filter and the phase response of higher order filters make it impractical for quality audio reproduction. By now the audiophile in you will agree that the 8 bit PWM audio isn't a prize. ![]()
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