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Unread 28-12-2006, 17:21
Dave Flowerday Dave Flowerday is offline
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Re: what usb -> serial adapter should i get?

Quote:
Originally Posted by Astronouth7303 View Post
If you want a real test of an adaptor, just hook it up to the dashboard, switch it to RC mode, and start reading data. Because the dashboard is set to the highest baud normally supported (115200), any USB adapter not able to handle it will bork.
The dashboard runs at 19200.
Quote:
Any adapter that handles this amount of data will be able to download code as rapidly as a native serially port. I'm not saying others won't, they'll just go slower.
No, for a few reasons. First, like I mentioned above the dashboard does not run at 115200 so this test won't work. Second, and much more importantly, is that these USB->Serial adapters are fully capable of 115200 speeds - that's not the problem. The problem has to do with buffering built into the USB->Serial adapter and the nature of the USB protocol. These adapters buffer up data coming from the serial port and only transmit it to the PC at certain intervals, either when the buffer fills or when some sort of timeout expires. This adds lots of latency since the way the IFI downloader works is to send commands to the RC and then wait for a response. So, each response takes a while longer than it should, which slows down the overall transfer. This is probably also why some just plain don't work at all.