384 khz ADCs?
Hello again everybody, just wanted to say that the first prototype for my assisting device for the blind, which uses scaled-down ultrasound is complete. Great many thanks to all of you who supported me with answers to my endless, often ridiculous questions. Thank you guyz a lot and a lot more.
The SigmaDSP showed itself to be a really amazing device for working with ultrasonic frequencies, and there is nothing else I could find which had an ability to built something so quickly and so efficiently. The thing is, when using ultrasound, I have to "load" the ADCs almost to the limit, since they digitize at 192khz and my working frequency is about 94. So of course the sine wave, generated on that frequency does not really look very "sinific". At the same time, really SigmaDSP is a potential king for those applications. So the question is, are you guyz planning, or at least thinking about giving the DSP an ability to digitize things at 384khz? This would really open lots of new ways for SigmaDSP, since again, nothing is better at present for ultrasonic applications, the only limiting factor here is the ADCs/DACs speed.
Hi Skfir,
Thanks for your input, and for using our parts! We do not have any plans to increase the sample rate by a factor of 2, however, you can push the rate higher by about 5% to 200 kHz if that would help. By scaling MCLK up to 12.800 MHz (or 25.6 MHz), you should be able to achieve stable performance at Fs = 200 kHz.
Best regards,
Coleman
Got it. Thanks!!
Is there any way to modify eval board (1701) in order to scale it? Or it is something complicated? Sorry I just have never made anything with clock generators.
I don't think you'll be able to push it past the 5% Coleman suggested. All of the clocks are derived by internal integer clock dividers, and we only guarantee the timing specs within a certain range. If you push the master clock past 5% above its recommended maximum, then there's no guarantee that the device will behave as expected.
You would need to change the crystal/oscillator on the board to the new frequency. Which exact model number eval board do you have? We might be able to recommend a replacement part.
Hi Coleman & Skfir,
The original 12.288MHz crystal (according the BOM in the EVAL-1701MINZ manual) is the
Abracon Corp
ABM3B-12.288MHZ-10-1-U-T.
A 12.8MHz replacement is
Abracon
ABM3B-12.800MHZ-10-1-U-T,
Digi-Key 300-8199-1-ND.
Bob
Thanks, Bob!
I wasn't sure if he is using the EVAL-ADAU1701MINIZ or the EVAL-ADAU1401EBZ. The Abracon programmable oscillators work very well; they are configured by DK before shipping, per your instructions at the time of order.
Regards,
Coleman
Thanks heaps guyz!
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