RT1052 SEMC in DBI mode Speed of communication

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RT1052 SEMC in DBI mode Speed of communication

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XuT
Contributor I

I try to use the SEMC in DBI mode in order to communicate with the FPGA ,But no matter how I set the speed is only about 7M,Here  is my initialization code and screenshot of the logic analyzer.How to set up to improve communication speed?

Thanks!

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jeremyzhou
NXP TechSupport
NXP TechSupport

Hi,
Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
Just as Nick suggested, I think you'd better to check the value of the semcclock at firstly.

Have a great day,
TIC

 

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nickwallis
Contributor V

@XuT I don't see anywhere in your code where you are setting up the clock source for the SEMC module?

The default clock frequency for the SEMC module is 8MHz, but it can go up to 166MHz depending on which power mode you are running.

Search for "SEMC_CLK_ROOT" in the reference manual.

Typically, one might run the SEMC module off the PLL2 clock (which is normally 528MHz) and divide it down using the PLL2 PFD divider and/or the SEMC_PODF divider.

Here's an example, you might need to modify it for your application but you get the idea:

	// Set the PLL2 PFD divider to /29,
	// so the output frequency is now 528MHz * [18/29] = 327MHz
	CLOCK_InitSysPfd(kCLOCK_Pfd2, 29);

	// Set PLL2 as the clock source for the SEMC module
	CLOCK_SetMux(kCLOCK_SemcMux, 1);

	// Set the AXI_PODF (a.k.a. SEMC_PODF) divider in CBCDR to /2,
	// so the actual SEMC module clock is 327MHz /2 = 163.86MHz
	CLOCK_SetDiv(kCLOCK_SemcDiv, 1);

 

BR

-Nick

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XuT
Contributor I

I did not include the code of initialize the clock,Here are my relevant Settings

CLOCK_SetMux(kCLOCK_SemcMux,0); //PERIPH_CLK AS SEMC SOURCE,PERIPH_CLK=600M
CLOCK_SetDiv(kCLOCK_SemcDiv,3); //SEMC Clock=600/4=150Mhz

 

 I've printed semcclock value is 150M

semcclock=CLOCK_GetFreq(kCLOCK_SemcClk); //150M

 

And  when I read in 32-bit addresses,In a period of CS pulling down,The frequency of the two reads is exactly 40M

 

 

 

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jeremyzhou
NXP TechSupport
NXP TechSupport

Hi,
Whether you mean the frequency of the SEMC CLK is independent of the read and write operation.
Hope it helps.
Have a great day,
TIC

 

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XuT
Contributor I

The operation to read may be related to the following parameters:

dbi_config.tCsxSetup_Ns=0;
dbi_config.tCsxHold_Ns=0;
dbi_config.tWexLow_Ns=5;
dbi_config.tWexHigh_Ns=5;
dbi_config.tRdxLow_Ns=5;
dbi_config.tRdxHigh_Ns=5;
dbi_config.tCsxInterval_Ns=2;

And the interval between reads:

for (index = 0; index < datalen; index++)
{
sdram_Buffer[index]= sdram[index] ;
//SEMC_SendIPCommand(SEMC,kSEMC_MemType_8080,sdram,kSEMC_NORDBICM_Read,1,&sdram_Buffer[index]);
}

If user IP command is only 1M 。Is there any other faster way to read it

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jeremyzhou
NXP TechSupport
NXP TechSupport

Hi,
Thanks for your reply.
According to your current setting of the dbi_config struct, it's close to the max performance actually. So I'm afraid it's hard to improve the speed of reading or writing operation.
Have a great day,
TIC

 

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