Re: Sending data direct to USB in OSX
Re: Sending data direct to USB in OSX
- Subject: Re: Sending data direct to USB in OSX
- From: Doug McNutt <email@hidden>
- Date: Sun, 14 Mar 2004 19:30:49 -0700
At 17:58 -0500 3/14/04, Graff wrote:
>
Isn't the /dev directory the attachment point for the device in question, not the drivers per se? It sounds like the driver did the right thing and properly translated the text you sent to it. I'm not sure if I'd trust this method without prior knowledge as to if the device driver handles input in this manner. For example, if there was a USB drive at the other end of that USB cable what would sending raw text do? Create a file and start filling it with the data? Start overwriting the disk headers with the text? You don't really know if you haven't read the documentation and thus you could cause big trouble.
The Delcom folks seem to know what they're doing but they are UNIX-oriented rather than Mac-oriented. USB devices have registered address information which allows a "driver" to know which physically connected USB device to connect to. When you're using the Delcom sampler you're using one of their registered addressed which will not be mistaken for a disk. When a hot-plugin occurs the registered address gets converted to one of 127 local USB addresses which are guaranteed to be unique on a particular USB.
They do provide rather complete documentation. You can even get the connector pinouts and expected voltages from theirs. Would that Apple would be so complete.
Yes. I'm fairly certain that going directly to /dev/ bypasses stuff that Apple does in the Aqua/Cocoa/NextStep/Classic/whatever API. But we are told that "It's UNIX underneath" and it seems to work that way without disturbing other USB thingies - at least the M$ Intellimouse and an ADB keyboard with a Griffen adapter. I believe it's perfectly legal, in OS neXt, to write ANSI C code that addresses a device when compiled and linked with Gcc.
Should you build a product for distribution using Delcom products you would have to register you own USB identifier. And no. I don't have any financial connection with them.
--
--> There are 10 kinds of people: those who understand binary, and those who don't <--
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