Getting digital microphones to work on EVAL-ADAU1777Z ?
I am trying to get a digital microphone input to work on EVAL-ADAU1777Z.
I have successfully brought up examples using 4 analog input channels through the ADCs.
I have some digital PDM mems microphones (SPH0641LU4H-1, Knowles). They look similar to some of the obsolete Analog Devices digital microphones (ADMP521Z). I have made a small PCB to adapt a digital microphone to J6 or J6 sockets, following the Fig.51 schematic in the eval board user guide.I also referenced the obsolete Analog Devices EVAL-ADMP521Z user guide (which seems to have a socket and pinout matching the EVAL-ADAU1777Z).
This microphone board only has 1 mic and 1 channel, although most of the setups I have seen use two digital mic's sharing a data line with L and R using rising/falling edges of the clock or vice versa.
I have followed the instructions on page 12 of the UG-1055 EVAL-ADAU1777Z user guide.
1) Set the pin/pad control according to Fig. 34 (MP6 set as Clock Output)
2) Set the BCLK value according to Fig. 35
3) Set the decimator panel to Fig. 36 (according to digital mic 0/1 or 2/3)
I am unable to get any audio output following the EVAL-ADAU1777z user guide. Are there additional settings/jumpers that I need to place to connect the clock, data, and Vdd/GND to the microphone daughter board?
Are there any more settings in SigmaStudio that need to be made to get digital microphones working with this eval board?
On a scope, probing across J7 (after programming with SigmaStudio), I get:
pin 1 GND
pin 2 GND
pin 3 3.07186MHz clock
pin 4 3.07186MHz clock
pin 5 GND
pin 6 GND
pin 7 GND
pin 8 Vdd 3.3V
pin 9 GND
pin 10 GND
pin 11 Vdd
pin 12 Vdd
digital microphone
pdm microphone
Integrated/Special Purpose A/D Converters
adau1777
Audio CODECs
Hello HonestEffort,
ADI sold off the MEMS microphone product line to Invensense so you can still find the ADMP521 but it is now called the INMP521.
Can you attach your project? There are some many ways that you can lose the signal that it will take too long to go through all of them. Let us have a look at your project.
Thanks,
Dave T
Dave,
Thanks for the reply. As an update for anyone in the same boat, there are a few of the old ADMP521 eval boards in stock (obsolete items) on digikey, and also a few on ebay. I had considered purchasing one just so I could eliminate the hardware side, as my demo boards were prototypes made on an LPKF and soldered with manually-applied paste, manual placement, and reflow. Obviously, there is some room for hardware error.
At any rate, in preparation for uploading my SigmaStudio project, I attempted to bring up the prototype digital microphones again.
This time, for whatever reason, I was successful. The schematic is very limited (just an input, a T, and an output) but it is able to function. I am now confident that the prototype board microphone hardware is working, and I can slowly add the functionality I need on the DSP.
I will attempt to upload a working project file to the original post to help other future readers.
Thanks,
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