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Mar 17, 2009, 02:16 PM
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sonar soundcard lives


Luckily 4 U, the Linux kernel can be a software bus analyzer. Go into linux/drivers/usb & use printk's to dump the buffer contents. U need to stop searching the Goog for bus analysers.

5 days of insanely difficult assembly language debugging & the home made soundcard finally started working. The USB driver ended up being under 1000 bytes, quite a bit less than the host we did before. There R no interrupts for USB. U have to use polling, which slows it down.

It can do 150khz before running out of clockcycles. That's 1.2 megabits coming out of a PIC. It can only do 23khz before the sound quality starts deteriorating. U need 150khz for sonar. The Goog is offline, so all U get is a picture of the waveform.

GPS aided heading only works in hovers. It falls over in horizontal movement. Going to acceleration doesn't work. That leaves washing out velocity or forgetting about it when translating.

Must remember to try adapting the sonar ping rate based on velocity. Maybe 1Hz when moving slowly & 10Hz when moving fast. It could either make it more bearable or make it sound radioactive.
Last edited by Jack Crossfire; Mar 17, 2009 at 02:22 PM.
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