topic Re: Changing System Clock Frequency can not speed up processing speed when using MPC5744P in MPC5xxx

Changing System Clock Frequency can not speed up processing speed when using MPC5744P

bruceye — Sat, 26 Aug 2017 09:27:56 GMT

Hi :

I have a problem to speed up the calculation of the MPC5744P by changing the system clock frequency.

First of all, 16 MHz IRCOSC was used as the system clock ( MC_ME.RUN0_MC.B.SYSCLK = 0;)and I tested the time for MPC5744P to process a formula, it takes around 100us (Testing by PIT) .Then I used the primary PLL (PHI) as the source of system clock ( MC_ME.RUN0_MC.B.SYSCLK = 2), so the system clock frequency is supposed to be 160MHZ. But the processing time stayed unchanged .

Could you give me some advice on why I cannot speed up processing speed by changing system clock frequency ?

Thanks

Bruce

Re: Changing System Clock Frequency can not speed up processing speed when using MPC5744P

davidtosenovjan — Tue, 29 Aug 2017 09:47:45 GMT

Hi, it is not supposed to be changed. PIT uses IRC as clock source:

Re: Changing System Clock Frequency can not speed up processing speed when using MPC5744P

bruceye — Sun, 03 Sep 2017 02:38:18 GMT

Hi David：

Thank you for your reply.Probably because I did not express my problem clearly that you misunderstood what I mean .

My problem is I can not speed up the microcontroller's speed by changing the clock source of the system clock(from 16Mhz to 160Mhz).Using PIT was just to detect how long it takes for a microcontroller to run a program.The result is that I can not speed up processing speed by changing system clock frequency.

So could you please give me some advice again ?

Thank you

Bruce

Re: Changing System Clock Frequency can not speed up processing speed when using MPC5744P

davidtosenovjan — Mon, 04 Sep 2017 08:08:17 GMT

I see.

Please pay attention to following example code, functions SysClk_Init and PeriClkGen_init:

Example MPC5744P PinToggleStationery S32DS

Hope it helps.

Re: Changing System Clock Frequency can not speed up processing speed when using MPC5744P

xiaopi — Tue, 17 Oct 2017 11:45:07 GMT

hi,i have the same problem just like you faced.coule you give you email or wechat,i really want to know how to speed up the microcontroller's speed.

my email is 382215239@qq.com,you can contact me also.