Conclusion

The AVR® core utilization results are summarized in the table below. A column for a CPU clock of 20 MHz is also provided since many AVR® devices have this clock speed as an upper limit.

Table 1. AVR Core Utilization Results
Demodulator Type ADC Sample Rate FIR Filter Taps Downsampling Factor AVR® Core Utilization (16 MHz Clock) AVR® Core Utilization (20 MHz Clock)
AFSK 6250 Hz - 1 29.3% 23.4%
AFSK with additional filtering 12500 Hz 15 2 61.9% 49.5%
Near-ultrasonic FSK 50000 Hz 9 8 66.6% 53.3%

These results confirm that the 8-bit AVR® core is capable of high levels of performance, even when the application requires some digital signal processing and is written in a high-level language. Next time you're evaluating microcontrollers for a project that involves sampling an analog signal with an ADC and performing some processing of that signal, consider prototyping it on an 8-bit AVR® microcontroller. Its performance, coupled with its low-power consumption and low cost, may surprise you.