AnsweredAssumed Answered

Help with MCF5475 speed problem.

Question asked by Diego Medina on Feb 17, 2010
Latest reply on Mar 12, 2010 by TomE

Hi, I'm using a Coldfire V4e MCF5475 and I have a problem. It seems like the core speed isn't as fast as it should be, 
I've been working in several Colfire MCU from MCF51QE128, MCF5213, MCF5249 and this is the only time such problem as occur. 

I'm just using the Coldfire Core and the DMA controller as the masters of the XL bus, the FlexBus, PCI, and other peripheral are disable. The CF core is the master of the XL bus and the DMA acts like the secondary master, all code and user variables are loaded into the Core SRAM memory, the clock ratio is set as default 1:4. 

The code is very simple, just putting a GPIO signal in High and Low state to check speed, also using a very simple filtering routine to check the operations speed. But the results are very poor, the GPIO only gets 1MHz while in the MCF51QE128 gets 4MHz, the filter routine takes 17us while in the MCF5249 takes 7us, I´m using exactly the same code for all MCU. 


I hope you could help me, If I'm doing something wrong or maybe something I've not considerate yet. 


I'll apreciate any kind of help.