Can you run the clock @ anything higher than 12MHz if one wants to drive USB with it. I want to use one of these things but 12MIPs is worse than arduino(granted that it is 32 bits).
The input clock can be multiplied using a PLL. I run an LPC2148 application at 60 MHz.
Leon
Does the USB still work when the core is running at that speed. The sparkfun boards have 12MHz clocks.
You need to run at 48 MHz - see the User Manual.
Leon
Because it has a 12Mhz crystal doesn’t mean it’s just running 12Mhz. Welcome to the sometimes confusing world of PLL’s. Some chips, like these ARM chips that run at higher Mhz use PLL’s to multiply the incoming clock signal in order to use cheaper crystals.
leon_heller:
You need to run at 48 MHz - see the User Manual.Leon
Just the USB PLL needs to run at 48MHz. The core can be run at anything over 18MHz and the USB will still work.
CCLK uses PLL0, the USB clock uses PLL1. There are examples of how to set them up on page 34 of UM10139.
Leon