Mic Array V2.0 accessing DOA and mic samples

Products & Technology ReSpeaker
#1

I am trying to write an application in C++ that

  1. read samples from the microphones (looking at using ALSA from portaudio)
  2. if samples > threshold, then get the DOA (using libusb and reading the registers)



    It seems that I cannot do both? If I read registers with libusb, and automatically detach/attach the kernel driver, then I can no longer see the mic array 2.0 in the list of devices using arecord -l



    Is there some way to use both together, or alternatively can I read the samples directly via libusb? When I look at the libusb list of interfaces, I can see it has 5 interfaces, are these to access the 4 microphones directly?
#2

I have simplied my program so it does the bare basics to test:



After reboot, I can see the respeaker device
</s><i> </i>>arecord -l **** List of CAPTURE Hardware Devices **** card 1: ArrayUAC10 [ReSpeaker 4 Mic Array (UAC1.0)], device 0: USB Audio [USB Audio] Subdevices: 1/1 Subdevice #0: subdevice #0 <e>

My code does the following

  1. Initialises libusc
    </s><i> </i>libusb_context *ctx = NULL; int resp = libusb_init(&ctx); <e>
  2. Opens the device
    </s><i> </i>respeaker= libusb_open_device_with_vid_pid(NULL, RESPEAKER_V2_MIC_ARRAY_VENDOR_ID, RESPEAKER_V2_MIC_ARRAY_PRODUCT_ID); <e>
    where
    </s><i> </i>#define RESPEAKER_V2_MIC_ARRAY_VENDOR_ID 10374 #define RESPEAKER_V2_MIC_ARRAY_PRODUCT_ID 24 <e>
  3. sets auto detach for the kernel driver
    </s><i> </i>int resp=libusb_set_auto_detach_kernel_driver(respeaker,1); <e>
  4. Claims the interface
    </s><i> </i>int rp = libusb_claim_interface(respeaker, 0); <e>
  5. Releases the interface (this should reattach the kernel driver)
    </s><i> </i>int r = libusb_release_interface(respeaker, 0); <e>
  6. Closes the device
    </s><i> </i>libusb_close (respeaker); <e>
  7. Closes the context
    </s><i> </i>libusb_exit(ctx); <e>

After my program runs I can no longer see the device

</s><i> </i>> arecord -l **** List of CAPTURE Hardware Devices **** <e>

There are no errors reported.
[code]
[timestamp] [threadID] facility level [function call]

[ 0.022655] [00000739] libusb: debug [libusb_get_device_list]
[ 0.023049] [00000739] libusb: debug [libusb_get_device_descriptor]
[ 0.023151] [00000739] libusb: debug [libusb_open] open 1.4
[ 0.023303] [00000739] libusb: debug [usbi_add_pollfd] add fd 10 events 4
[ 0.023403] [00000739] libusb: debug [libusb_kernel_driver_active] interface 0
[ 0.023577] [00000739] libusb: debug [libusb_claim_interface] interface 0
[ 0.024912] [00000739] libusb: debug [libusb_release_interface] interface 0
[ 0.028316] [00000739] libusb: debug [libusb_close]
[ 0.028647] [00000739] libusb: debug [usbi_remove_pollfd] remove fd 10
[ 0.029306] [00000739] libusb: debug [libusb_exit]
[ 0.029588] [00000739] libusb: debug [libusb_exit] destroying default context
[/code]


I have also tried manually detaching the kernel driver before I claim the interface and manually attaching the kernel driver after I release the interface, but it does not seem to make any difference



I note that when I release the interface, I can see the following transactions over the usb bus
</s><i> </i>b0e82400 1861717967 S Ci:1:004:0 s 80 06 0303 0409 00ff 255 < b0e82400 1861718384 C Ci:1:004:0 0 62 = 3e035200 65005300 70006500 61006b00 65007200 20003400 20004d00 69006300 b0e82400 1861718430 S Ci:1:004:0 s 80 06 0301 0409 00ff 255 < b0e82400 1861718752 C Ci:1:004:0 0 12 = 0c035300 45004500 45004400 <e>
I am not sure what this is actually doing?

Edit: A SET_INTERFACE control request will be sent to the device, resetting interface state to the first alternate setting.



Can anyone help me debug why I cannot see the device after executing my program? I want to be able to read the registers for angle of arrival, and also capture samples via portaudio or some other ALSA based driver.



OR



IS there another way I can achieve this? for example, could I read the samples via libusb? What is the API to do that?

#3

What are each of the interfaces doing for this device?
</s><i> </i>> usb-devices T: Bus=01 Lev=03 Prnt=03 Port=01 Cnt=02 Dev#= 4 Spd=12 MxCh= 0 D: Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=2886 ProdID=0018 Rev=02.00 S: Manufacturer=SEEED S: Product=ReSpeaker 4 Mic Array (UAC1.0) C: #Ifs= 5 Cfg#= 1 Atr=80 MxPwr=500mA I: If#=0x0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=snd-usb-audio I: If#=0x1 Alt= 0 #EPs= 0 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio I: If#=0x2 Alt= 0 #EPs= 0 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio I: If#=0x3 Alt= 0 #EPs= 0 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none) I: If#=0x4 Alt= 0 #EPs= 0 Cls=fe(app. ) Sub=01 Prot=01 Driver=(none) <e>