Hello, Does USB audio device class for (LPC ARM based micros) support multiple audio streams?
I found USB speaker example but would like to implement microphone input as well (headset scenario) for voice quality audio.
Can anybody confirm that is possible with Keil USB audio library?
Regards, Piotr
> Does USB audio device class for (LPC ARM based micros) support multiple audio streams?
Yes. Each audio stream is assigned to dedicated AudioStreaming interface. USB Audio supports multiple AudioStreaming interfaces. You'll see a typical example descriptors and detailed description in the attached doc of this MS page.
"USB Handset Peripherals and Windows" on MS WHDC www.microsoft.com/.../usbtelephony.mspx
USBtelephony-v091.doc download.microsoft.com/.../USBTelephony-v091.doc
3 Descriptor Hierarchy This USB handset device includes an AudioControl interface (0), two AudioStreaming interfaces (1 and 2 â€" one for capture and one for render), and a HID interface (3). > I found USB speaker example but would like to implement microphone input as well (headset scenario) for voice quality audio. Can anybody confirm that is possible with Keil USB audio library?
The requirement for this configuration is just two isoc endpoints (and optional interrupt EP for HID), other than the default EP. Any LPC USB MCU will do. If you are talking about one of these example, you can extend them as you expected.
LPC2148 USB Audio Device Example http://www.keil.com/download/docs/308.asp
LPC2368 / LPC2378 USB Audio Device Example http://www.keil.com/download/docs/334.asp
Tsuneo