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A COMPARISON OF MICROCONTROLLERS AND DSPs

A Case Study
by Jerry Horn

Start ý Fine Tuning ý Turn Up the Volume ý Timing is Everything ý Storage ý Pricing ý Encore ý Sources and PDF

ENCORE

And now, a few closing remarks. The DSP56362 is also a good candidate for this application. The onboard data RAM is 11k ý 24 bits, which would provide up to 340 ms of storage at 32 kHz or 250 ms at 44.1 kHz. So, no external SRAM would be required. The DSP56362 is $6 more than the DSP56364, but you save $4 for the static RAM. And, the DSP56362 has more general-purpose I/O pins, as well as some additional hardware features (such as an S/PDIF output port). Combined with an EPROM and an AC ý97 codec, the basic electronics cost is $21 (compared to $19 for the DSP56364 and an AC ý97 codec).

There are a large number of DSP chips that could be used for this application. Texas Instruments, Analog Devices, and Motorola manufacture a variety of DSP chips. Cirrus Logicýs Crystal Semiconductor division manufactures DSP chips that are mainly intended for audio signal processing, as does AKM Semiconductor.

A partial list of companies that manufacture audio ADCs, DACs, and codecs is available.

Finally, not all guitar effects require an ADC, DSP, and DAC. There is a thriving presence on the Internet for classic guitar effects implemented strictly in analog. High-performance operational amplifiers (op-amps) are now inexpensive. So, an analog-only approach could be both cheap and high-performance. A list of a few Internet sites for old guitar effects circuits is available.

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