Yes, but high speed USB runs at 480Mbits/s, so there must be a DFS/PLL in the RTL chip to generate this clock from the 28.8 Mhz xtal. The multiplier (16.666) may be hard programmed, or it may be contained in the EEPROM. If it's in the EEPROM, then it can be changed. I thought I'd seen reference in a data sheet somewhere to a 25Mhz crystal option, so as long as it's not my memory playing tricks the multiplier must be programmable somehow. Cheers Malcolm ________________________________________ From: Ralph A. Schmid, dk5ras [[email protected]] Sent: 15 September 2014 09:37 To: Malcolm Robb; 'Kevin Reid' Cc: [email protected] Subject: RE: Maximum sampling frequency questions.
Doesn't it derive the USB clock from the 28.8 MHz crystal? In this case you are out, USB needs the correct frequency to work. Ralph.
