Thanks for the update. That was helpful. -Earlence
On Mar 11, 7:08 pm, Chris Stratton <cs07...@gmail.com> wrote: > Depending on the transfer function of the audio output system, it may > be possible to simply shove moderate rate non-return-zero encoded data > through it by delivering PCM samples to the audio driver, and recover > it with an appropriate receiver circuit on the other side. > > What is certainly possible is to implement a low rate modem using > frequency shift keying between two audio tones, or more complicated > phase and audio modulation constellations, and recover that. > > For a limited set of discrete functions, sending DTMF type tones and > using a DTMF receiver IC or algorithm is another possibility. > > On Mar 1, 7:24 am, Earlence <earlencefe...@gmail.com> wrote: > > > but playing sound is different from controlling a device right? > > or they just send data bytes which are control signals for the > > external device :) (instead of sending pcm data) > > > Cheers, > > Earlence > > > On Mar 1, 12:38 pm, Stefan Schake <caytc...@gmail.com> wrote: > > > > Hey, > > > > because user space apps are allowed to play sound? You certainly don't > > > get a perfect digital signal but its apparently good enough. > > > > Greetings > > > > 2011/2/28 Earlence <earlencefe...@gmail.com>: > > > > > Hi, > > > > > I have seen from this app (http://www.squareup.com) that they are > > > > driving an external device thru the headset jack with just a userspace > > > > app. > > > > I have checked the kernel sources and seen htc_35mm_headset.c and > > > > htc_headset.c which contains driver code for the HTC 2 Wire protocol. > > > > Its my understanding that to drive a custom device, a custom driver > > > > would be needed. and to replace a driver, root access is required. How > > > > is that app then able to drive a device on the headset jack from java > > > > userspace? > > > > > Cheers, > > > > Earlence > > > > > -- > > > > unsubscribe: android-kernel+unsubscr...@googlegroups.com > > > > website:http://groups.google.com/group/android-kernel -- unsubscribe: android-kernel+unsubscr...@googlegroups.com website: http://groups.google.com/group/android-kernel
