ADAU1701 with I2S slave in, I2S master out?
Thread Summary
The user is experiencing a lockup issue with the ADAU1701 when receiving I2S data from an external ADC while operating as an I2S output master. The solution involves connecting the OUTPUT_LRCLK and OUTPUT_BCLK pins to the INPUT_LRCLK and INPUT_BCLK pins, as well as to the external ADC, to ensure proper clock synchronization. The user will test this configuration and verify if the LRCLK/BCLK outputs and SPI/I2C access are affected during the lockup.AI Generated Content
Hi all,
I have been using the ADAU1701 with a reasonable amount of success, but I just ran into a snag..
I have already managed to get the ADAU1701 to output (as I2S master) to an external DAC. However, I also want it to receive data from an external ADC (as I2S slave).
Or in other words, I want to get these things working simultaneously:
ADAU1701 as I2S input slave, receiving data from ADC
ADAU1701 as I2S output master, sending data to DAC
Is it possible to do this, i.e. have the ADAU1701 be a slave for the input and a master for the output? Or will I need it to be slave for both input and output?
Extra details:
- everything is running off of the same master clock.
- the digital input signals have to travel through ~2cm of wire - could asymmetrical delay in the wires cause this problem?
- [input Lrclk_in, input Bclk_in] and [In Lrclk_out, In Bclk_out] are not connected together on the PCB.
I have been playing with this for awhile now - it works when there is no serial input data, but as soon as the serial input data starts, the whole processor locks up. I've attached a screenshot of my hardware diagram.
Thanks a lot
Cheers,
Shen
Audio Signal Processors
serial
i2s
SigmaDSP Audio Processors
adau1701
Hi Shen,
When you say the whole processor locks up, do you see the I2S serial output ports LRCLK/BCLK signals go away, or are these clocks still there and it does not output audio data on the SDATA ouptut pins? And do you still have host microctontroller SPI/I2C access after the processor locks up? Not sure if the trace length differences are causing this, but perhaps if the output/input serial clocks are not tied together.
The ADAU1701 datasheet page 46 states the following:
"The clocks of the input port function only as slaves, whereas the output port clocks can be set to function as either masters or slaves (...) If an external ADC is connected as a slave to the ADAU1701, use both the input and output port clocks. The OUTPUT_LRCLK (MP10) and OUTPUT_BCLK (MP11) pins must be set to master mode and connected externally to the INPUT_LRCLK (MP4) and INPUT_BCLK (MP5) pins as well as to the external ADC clock input pins. The data is output from the external ADC into the SigmaDSP on one of the four SDATA_INx pins (MP0 to MP3)."
Based on these comments in the datasheet, it seems that 2 system configurations using an external ADC are possible:
-JT
Hi JT,
Thanks for the reply!
When I said 'the processor locks up', this is what I meant:
- I had one LED connected to a GPIO on the ADAU1701. This LED was set to blink on a 1-second interval, just to indicate that things were still working.
- As soon as the (I2S master) ADC started sending data to the ADAU1701, the LED stopped blinking and was stuck in the 'on' position.
I am not sure if the LRCLK/BCLK outputs also stopped working - I will have to measure these the next time I am in the lab. I also did not try to program the ADAU1701 when it was in this 'locked up' state - I will try that as well. As soon as the ADC stopped sending data, the LED started blinking again.
I think you may be right about having to connect the in/out BCLK/LRCLK together. I will try that as well (with the ADC as master) and let you know how that goes.
Thanks again,
Shen
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