New Electronics Idea...

DIY timing systems
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SlartyBartFast
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New Electronics Idea...

Post by SlartyBartFast »

Well, more meandering thoughts concerning possible ways to build and program timers.

Looking at past designs, I found the parallel cable timer and it got me thinking:

How about something similar over USB?

I've found a number of schematics for USB to I2C, so the detectors could be wired to any Digital I/O Extender chip...

Thoughts?
dna1990
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Re: New Electronics Idea...

Post by dna1990 »

I don't know for sure myself, but I believe there are additional timing concerns in USB over parallel.

But the low level stuff does not bother me as much as relying on modern day PCs to do 'any' of the timing. We had a great deal of time drift (full seconds) when a Windows driver went goofy on a new USB mouse. To do timing at the PC (in my opinion) means a DOS/Linux type dedicated computer. Even then, cable length and heat buildup can still add to variance.

I think the way to head is always have the timing done by separate electronics running with minimal circuitry and interference on a known crystal. It does not have to be perfect in terms of earth-seconds, just very consistent from lane to lane and race to race. Then those results are fed to the PC (USB, serial, Bluetooth, etc) for display and management.
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SlartyBartFast
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Re: New Electronics Idea...

Post by SlartyBartFast »

Yeah, I started reading up on USB packet size and all....

Not sure how quick it is to work on interrupts.

I'm leaning towards a simple timing circuit and controller that spits time and trigger info out into the serial buffer.

Use the computer to sort out reporting but leave timing to the microcontroller counters.
altontoth
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Re: New Electronics Idea...

Post by altontoth »

I actually have a USB based timer in the works. It's powered via an Atmega microcontroller, and can monitor up to 5 lanes at a time. I have the hardware mostly finished...I just need a hand with programming for the device. I will be making kits / complete systems available as soon as I can get the programming finished. It's a USB connection, and it can spit back the actual race times for Grand Prix (or any other Com-port compatible serial timer software) to deal with. If you have any sort of experience with the Atmega micro controller, drop me an email.
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