ATmega8U2 usb timing inaccuracy

Other Hardware General Electronics
1

formally i used the arduino duemilanove. The timing of the ftdi chip was perfectly 1 ms(if you set the driver to 1ms). The arduino uno has the Atmega8U2 chip. When I set the driver to 1 ms accurate and the buffer size to 64. it has a accuracy of 3-4ms!! This means if I make a timer which sends out every ms an event, 3-4 events come in, in time slots of 3-4 ms. So not 1 event every 1 ms.

I have uploaded the last program for the Atmega8U2 with the flip installer, but it gave me no improvement. I read that the implementation of the Atmega8U2 software is not open source.

I cant find out whats wrong here, the driver or the atmel implementation. We are using the arduino as a basic component for nearly all research applications at the radboud university of nijmegen. This would mean we have to give up our love for the arduino....

We really hope we are not alone on this.

Regards,
pascal

2

"This would mean we have to give up our love for the arduino...."

Or make you own boards. The FTDI chip is difficult to solder down without proper tools, but if you get it presoldered on a breakout board and attach it to a minimal atmega board you could have all the same functionality in whatever form factor you'd like. Or even just use it to download only & run the boards indepently of the PC after that if that's what your application calls for. Maybe build up Serial arduinos (boards are available at mouser), use USB/RS232 adapter cable for downloading/debug.
Lots of ways to avoid the ATMega8U2 design.

3

I read that the implementation of the Atmega8U2 software is not open source.

Where did you read that?

https://github.com/arduino/Arduino/tree/master/hardware/arduino/firmwares