MPC5744P sys_clk cann't config to 200Mhz

[xiaopi]

like the appendix m5744xinit.c,i config the PLL1 to 200Mhz.And i config the MC_ME.RUN0_MC.R to choose sys_clk=PLL1=200Mhz.

And in main(void),i use SIUL_ToggleIO(SIUL_PD5) to observe the time of system running time.But i found that the time of SIUL_PD5 togglling is 120us.So i calculated the time of sys_clk,it seems to be 40Mhz not 200Mhz.

I really don't know why the program within the main function runs so slowly?

Original Attachment has been moved to: m5744xinit.c.zip

[petervlna]

Hi,

To make your Clock configuration easy and simple we have developed excel tool for clock configuration.

You just have to insert the required frequencies and it will generate code for you.

https://community.nxp.com/docs/DOC-328021 

Peter

[xiaopi]

Sorry,you may misunderstand what i say.

Do you see the The attachment I uploaded？I relly config the clock to 200Mhz as the excel tool for clock configuration.But the speed of  instructions running is not 200Mhz,it runs too slowly just like that the speed is 40Mhz.

And also there is another problem,when i debug this instructions->"MC_CGM.SC_DC0.R = 0x00030000;".the mpc5744 can't debug program any more.The reset signal is 0 all the time.There is  any advice to solve this problem?

Thank u Peter.

[petervlna · Accepted solution]

Hello,

First, your core is running at 200MHz system clock supplied by PPL1.

I hope you realize that 1 instruction can take 4-5 clock cycles to execute.

I recommend you to measure CLKOUT if you want to check your PLL output.

Peter