What dsp chip to use for guitar effects pedal?
Hi, everyone!
I'm currently in my final year at the university, and for my project I would like to build a digital guitar effect pedal. The general idea would be to use an AD1938 CODEC for AD/DA conversions, a dsp chip( currently I have an ADAU1446) for processing the data, and to create a custom graphical user interface with PIC micro controller which could communicate with the dsp through I2C to change some parameters(ex. distortion gain, on/off effects, etc.). I would like to know if this could be achieved with my current dsp chip? If not, what other dsp should I use? - In the past I used dsPIC for sound processing, but i wanted to go with something more professional.
Any response would be appreciated.
Thanks in advance.
Audio Signal Processors
i2c
adau1446
ad1938
Integrated/Special Purpose A/D Converters
SigmaDSP Audio Processors
Audio CODECs
dsp audio
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You could certainly use the components you mentioned.
If you are going to build your own stomp box, you may want to consider some other alternatives.
Power consumption is one of the larger considerations. Most effects boxes assume 9V battery operation with a pass thru function when your stomp box is not in use..
You might look at an ADSP-21479 and a lower power codec, since you won't need many channels. You wouldn't need the PIC at all in this case. Depending on the type of effects you want to try to create, you will likely want to oversample. You could do this by sampling at a high rate like 192k or interpolating and decimating at a lower rate. This is so you can avoid harmonic aliasing with non linear effects. Floating point DSPs can be helpful with many effects algorithms. The ADAU1446 is a nice part, but I think I would want to learn a little programming if I was doing a senior project. As an employer, I am always interested in projects that set students apart. Designing your own board and writing a little software is a nice exhibit in a job interview for a new graduate.
Al Clark
www.danvillesignal.com
If you do not use long delays would recommend adau1701.
Adau has built in ADC/DAC converter suitable for direct connection to analog amplifier effect loop - it simplifies design and decrease power consumption (but is still overloaded 9V battery).
You can use GPIO to switch effect without external microcontroler.
It will good idea do decrease sample rate for ex. 32kHz for more power reduction.
A lot of useful functional blocks for effects are built into the Sigma Studio software.
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