In SX Microcontrollers, SX/B Compiler and SX-Key Tool, dkemppai wrote:

[quote="Guenther Daubach"]
Dan,

some words on the USB key:

the bottleneck that limits debugging speed is the way how the SX20 on the SX-Key and the target SX communicate during a debugging session, and not the serial communication between the IDE and the SX-Key. The intra-SX communications can't simply made faster because the debugging process may not steal away too many clock cycles from the target SX, or the target's clock timing would be completely messed up. You may notice that even now, with the current timing between the target and the SX-Key, some jitter is caused while the device is debugged.

Therefore, switching to the FTDI direct drivers would not mean a speed increase. On the other hand, many users might have already installed the VCP driver for their SX-Blitz USB, or a Parallax USB/RS232 adapter, so the same driver can also be used for the SX-Key USB.

[/quote]

Guenther,

I have experimental data that suggests that the USB to serial converter does slow things down significantly. Try run the debugger in full speed walk, with the SX-Key on a real serial port, then on a USB serial port. I've seen significant decreases in the responsiveness. Cranking the USB settings up a little helps, but it's never as fast as a real serial port. Maybe the new "R" version of the USB chip hardware fixes some of that, but you're still going through the windows USB gobbly gook, then the ftdi drivers, then the USB to serial driver. 

If the USB to Serial isn't the bottle neck, why do I have so much trouble with the 'poll' button when using the usb to serial converter and not on the real hardware port? 

As far as the drivers are concerned, I believe the latest version of the VCP drivers include the Direct drivers. A firmware setting on the FTDI chip sets the (The RS232RL, as I see the USB Key has), will determine which drivers are loaded when windows enumerates the device. 

Just imagine how many users wouldn't have to try to figure out which com port the Key is on? The SX-Key software could scan for USB hardware when it starts...

Dan


P.S. Don't get me wrong here, I'm not trying to badmouth the effort. It's just that I think things could be done better, with very little effort spent in the process.

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