Building a DSP
Thread Summary
The user wants to build a DSP with 8 output channels for individual speaker connections, considering the ADAU1701 which supports only 4 DACs. The final answer confirms that using two ADAU1701 chips is feasible, requiring them to be clocked from the same master clock and connected via the serial data port. The user also inquired about using an 8-channel DAC like the WM8768 externally, which is possible if the DAC can receive standard TDM signals.AI Generated Content
Hello community,
I want to build a simple DSP with RCA inputs and outputs. I need a minimum of 8 output channels, where I will be connecting 8 speakers individually. After a little bit of searching I came across "freeDSP" that's powered by the ADAU1701 chip. I liked the simplicity of the design and would like to build something similar. Unfortunately, the ADAU1701 supports up to 4 DACs and I can't use it in my build unless there is a way to use 2 ADAU1701 chips in one board. Is this concept feasible? Or Is there maybe a comparable chip with 8 output channels?
Thread Notes
ambugua - Moved from StudentZone (Analog Dialogue) to SigmaDSP Processors & SigmaStudio Dev. Tool. Post date updated from Monday, May 1, 2017 6:12 PM UTC to Tuesday, June 24, 2025 11:29 PM UTC to reflect the move.
Audio Signal Processors
SigmaDSP Audio Processors
adau1701
Hi DaveThib
Would you be able to answer this user's question, please?
Thank you
Lisa
Hello zaxord,
Yes, the ADAU1701 is a great simple DSP with decent processing power and built-in converters. It does have four DACs but this is the only DSP we have that has that many DACs on-chip. So any other DSPs will have to have external DACs or Codecs (DACs with ADCs) as an external IC. Then we do have a codec that has four ADCs but only two DACs. So that is not a good choice. After that there is an 8-channel DAC but again, it requires another part and some complexity to implement it properly.
So your question about using two ADAU1701s is a valid solution. There are a few details. You will have to clock them from the same master clock. Then you will have to connect the two together using the serial data port. So you can exchange data between the two parts. There will be a small delay to transmit the data to the other part but you should be able to compensate for this using some delays. It is only one or two sample periods.
You can setup SigmaStudio to address, program and control more than one part. This way the program will all be on one schematic file for both parts.
So let me know if you have further questions.
Dave T
Hello Dave,
Thank you for your answer.
What if I wanted to use an 8-chanel DAC like the WM8768 as an external DAC and setup the ADAU1701 with serial data outputs (DIG0-DIG7) and deliver the signal to them from the analog input, is this possible?
Thank you for your support.
Hello zaxord,
Assuming the Wolfson part can receive standard TDM signals it will be fine. You have access to all 8 outputs from within the core.
Thanks,
Dave T
Please log in to reply.