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Looking at lpc2300.s from the RTX_blinky for example, it looks like cclk would end up running at 24mhz. Am I interpreting this correctly, and if so, why is it set so slow?
Dave
I haven't used the chip you are looking at but I can confirm that I understand the calculation to be Fcco = (2 * M * Fin ) / N
(page 36 of the user manual)
Not having looked at the example you are using I am guessing the settings for M and N are 4 and 4 - this would give 24 MHz in the above equation.
therefore I agree with you that 24 MHz is too low. According to the spec the acceptable range is 275Mhz to 550 MHz. According to the manual the output of the PLL is then divided down to provide the various peripheral and CPU clocks.
May be the example was copied from an LPC21xx one where the PLL works differently. These figures would then give a clock frequency of 48Mhz
Thanks. Actually the values were 8 and 4, so the frequency should be 48MHz. I missed that extra factor of 2 in the equation - it's always something simple.
If I am not mistaken, the maximum allowable frequency for the LPC2378 on the MCB2300 board is 72 Mhz.
However, I concur with your calculation of 48 Mhz.
Best Regards,
-=Rich=-