Other Parts Discussed in Thread: TLV320ADC3101, PCM1804
Hi,
I am considering using the PCM3070 and other devices which also include the miniDSP capability for use in a Pro Audio system design. However I have some rather unusual signal routing requirements and for the life of me I can not find the information to explain clearly the available signal routing options within the PCM3070. I have read the datasheet and various application notes and I have the impression that something is assumed but not explicitly stated. So perhaps you can help and clarify.
Within the PCM3070 there are two independent miniDSP blocks. There is also the possibility to configure a secondary I2S interface. My question is related to how and through which registers I can control routing of data both from and to the primary and secondary I2S interfaces. To try and be more specific I shall describe an example of what I would like to achieve.
I wish to use the ADC section of the PCM3070 to digitise 2 streams of data. Firstly I wish to configure 2 analog inputs in differential mode to accept a balanced line microphone input. This should be switched to the R PGA, and subsequently digitised by the R ADC. Further still this stream will then be processed by the fixed DSP functions and potentially further processed by the R half of miniDSP_A. Finally this stream should be routed to the Primary I2S DOUT, but NOT towards miniDSP_D or the DAC. The other 4 analog inputs I wish to be switched as single ended inputs onto the L PGA and L ADC, then handled by the L half of the digital processing blocks and L half of miniDSP_A, then routed out of the L ch of primary I2S DOUT. In essence this uses the ADC sections and miniDSP_A as if it where just like the a TLV320ADC3101.
I would like to be able to use the miniDSP_D as a input processing block for a different ADC, such as the PCM1804, To clarify, I wish to route L&R data from the PCM1804 into the primary I2S DIN and directly into the fixed processing blocks and miniDSP_D. However the output from miniDSP_D would then be routed out if the secondary I2S DOUT interface.
To add further to the complexity I would then like to route R Ch data from the secondary I2S DIN and unprocessed towards the DACs. Having L DAC ouput the same signal as R DAC but 180deg out of phase in order to use the L&R Line outputs as a differential input to a monitor amplifier. If the phase inversion is not possible. I could be content with a single ended output from just the R ch.
Can this be achieved. I can not find any information about how I can route I2S data within the PCM3070, and for that matter the same questions arises with other miniDSP products, but as most have only 1 miniDSP this is less of an issue. But with one thing that is attracting me to the PCM3070 is the dual miniDSP function.
In effect I am trying to use this miniDSP_D as a stand alone DSP block that I can insert in-line between the PCM1804 and my main processor in order to make use of it BiQuad functions as these are not available in the PCM1804 and I would like some equalisation on the balanced line inputs and have the same code block in my MCU controlling BiQuads in both the miniDSP_A and miniDSP_D to avoid having to run DSP code on my MCU.
I have included a simple block diagram of the proposed system to help you answer my question.
Many thanks in advance
Aidan
