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This thread is privately moderated by Jack Crossfire, who may elect to delete unwanted replies.
Apr 12, 2008, 06:37 AM
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Gumstix heartbreak


After banging on it for a day, found the BTUART received data from itself & received data from a PC. The PC could receive data from GPS & from the BTUART, but the BTUART couldn't receive data from GPS. The Verdex UARTS have a slightly higher switching voltage than they did on the Basix. The EM406 UART only goes to 2.8V.

The workaround is to raise GPS ground using diodes until the switching voltage is high enough. This gets 50% of the data through. Need a comparator.

In rough tests, the PXA270 622Mhz does 4x more neural network iterations than the PXA255 200Mhz using the old 3 module network. Not the 20x that http://docwiki.gumstix.org/Benchmarks led us to believe. Below 2500 iterations/sec, the CPU usage is 1%. Between 2500 & 10,000 iterations/sec, the CPU usage jumps 25% for every 2500 iterations/sec.

What seems 2 B happening is once the back propagation errors get below a certain point, the FPU starts grinding away very slowly. Observed it before with very long reverb tails.

With a 1 module network specificially written for the PXA270, the limit is 3000 iterations/sec.

Can't compare the new network since the PXA255 was destroyed.
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Apr 12, 2008, 09:50 AM
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xatled99's Avatar
Maybe it's getting bitten by denormalized floating point. Does your compiler have an option to flush denorms to zero?
Apr 19, 2008, 07:37 AM
BeeZaur 480
BowerR64's Avatar
I use blockbuster online too. Netflix disks were always trashed sometimes unplayable. So far so good with blockbuster.

Now back to the program *cough*


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