[wdmaudiodev] Re: Building an USB audio interface with a PIC18F4550
- From: Pete Gontier <pete@xxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Wed, 28 Mar 2007 15:43:06 -0700
The API you¹re suggesting may or may not suffice. You need to describe the
application you¹re trying to write. Post your description to the list,
because I¹m a driver developer and app developers will probably have better
insights into choosing an API for your app. I¹m just trying to make the
thread go faster.
? Pete Gontier <http://www.m-audio.com/>
From: Elios Elios Elios <eelioss@xxxxxxxxxxx>
Reply-To: <wdmaudiodev@xxxxxxxxxxxxx>
Date: Wed, 28 Mar 2007 16:56:33 +0000
To: <wdmaudiodev@xxxxxxxxxxxxx>
Subject: [wdmaudiodev] Re: Building an USB audio interface with a PIC18F4550
Hello, thanks very much!
At the end we are making our USB Device an USB Audio Class Compliant ... but
now we have some questions...
- Can I use my USB Device (USB Audio Class Compliant) with winmm.dll? If
not... Which DLL should I use for that porpouse?
I've controlled my soundcard with this DLL, but I don't know if I could
access to the driver USBAudio.sys... In fact, I only know "winmm.dll", but I
expect that WDM Audio Drivers are a lot of things...
this is my example (partial):
private const string mmdll = "winmm.dll";
// native calls
[DllImport(mmdll)]
public static extern int waveOutWrite(IntPtr hWaveOut, ref WaveHdr
lpWaveOutHdr, int uSize);
[DllImport(mmdll)]
public
static extern int waveOutOpen(out IntPtr hWaveOut, int uDeviceID, WaveFormat
lpFormat, WaveDelegate dwCallback, int dwInstance, int dwFlags);
[DllImport(mmdll)]
public static
extern int waveOutReset(IntPtr hWaveOut);
...
And my program use these functions.
Can I use this functions to control my USB Audio Device?
Could anyone send me an example of USB Audio programming with C# (ó C++)?
Thanks in advance!
>
> From: DJ Sisolak <dsisolak@xxxxxxxxxxxxxxxxxxxxxx>
> Reply-To: wdmaudiodev@xxxxxxxxxxxxx
> To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
> Subject: [wdmaudiodev] Re: Building an USB audio interface with a PIC18F4550
> Date: Tue, 27 Mar 2007 16:53:59 -0700
>> >Hi All,
>> >
>> >Answers dispersed below...
>> >
>> >Thx,
>> >DJ Sisolak
>> >Microsoft Corp
>> >
>> >-----Original Message-----
>> >From: wdmaudiodev-bounce@xxxxxxxxxxxxx
>> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Roberts
>> >Sent: Monday, March 26, 2007 10:56 AM
>> >To: wdmaudiodev@xxxxxxxxxxxxx
>> >Subject: [wdmaudiodev] Re: Building an USB audio interface with a PIC18F4550
>> >
>> >Elios Elios Elios wrote:
>>> > >
>>> > > I'm making my end of career project (telecomunications engineering),
>>> > > that consist in a USB interface for capturing audio by 4 channels. We
>>> > > are using as IC the PIC18F4550 of Microchip. We have made the PCB, and
>>> > > we have comunicated the PIC and the PC with an C# example that we have
>>> > > found in the WEB. This example is for low speed, and for audio isn't
>>> > > very good...
>> >
>> >To do 44.1kHz audio at 16 bits per sample with 4 channels takes 353
>> >kB/sec. That's double what a low-speed device can do. You'll need full
>> >speed.
>> >
>> >[DJ Sisolak] Correct, all spec compliant USB Audio devices MUST be full
>> speed.
>> >
>>> > > So, what is the better way to make an USB Audio Interface?
>>> > >
>>> > > I read the "USB Device Class Definition for Audio Devices 1.0" and the
>>> > > 2.0... I think that if we follow the specification, we could to
>>> > > control the interface with the driver Usbaudio.sys and programme it
>>> > > with an Native API like WDMAudio Driver (winmm.dll, isn't?), or Core
>>> > > Audio ...
>> >
>> >Yes, the best way to build an audio device is to meet the USB Audio
>> >Class Spec, as you describe above. The trickiest part is creating the
>> >descriptors to describe your architecture, and even that's not too hard;
>> >there are samples in the documents on the USB web site. You will want
>> >to do your streaming with an isochronous pipe.
>> >
>> >[DJ Sisolak] Again, correct. Streaming for USB Audio per the spec (MIDI
>> being the exception) is done via Isochronous pipes. Descriptor generation for
>> USB Audio 1.0 device is pretty straight forward from the spec. You may want
>> to look at the guidelines as posted on
>> http://www.microsoft.com/whdc/device/audio/UAA_HWdesign.mspx for some other
>> information on this.
>> >
>>> > > I read that there is a problem with USB 2.0 (the PIC18F4550 works in
>>> > > USB 2.0, full speed) and Usbaudio.sys... Somebody knows it?
>> >
>> >Not that I know of. There are a few discussions of this on the
>> >Microchip web site, but nothing negative.
>> >
>> >[DJ Sisolak] Full speed USB Audio devices should work just fine with USB 2.0
>> bus. There are some issues for getting a High Speed USB Audio 1.0 devices to
>> work though.
>> >
>> >
>>> > > Maybe the other solution can be to make a driver with Windriver... I
>>> > > have listened that is very easy to do. But in this way only we could
>>> > > to control our interface with our own driver... isn't?
>> >
>> >Making a simple driver with WinDriver might be easy, but making an audio
>> >driver of any kind is not easy. Unless you run into some very serious
>> >problem, you should strive to make your device USB Audio Class compliant.
>> >
>> >[DJ Sisolak] I heartily agree. If for some reason you feel that the
>> usbaudio.sys class driver does not fit your needs feel free to let me know
>> why.
>> >
>> >--
>> >Tim Roberts, timr@xxxxxxxxx
>> >Providenza & Boekelheide, Inc.
>> >
>> >******************
>> >
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>> >
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>
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