iMX117H SDRAM Too Slow

[MFurkan]

Hi,

I have a custom board with NXP iMX1176 chip, using the following code ;

#define buffersize (1U*1024U*1024U)
volatile uint32_t test_buf[buffersize];

bool x = false;
while (1) {
for (uint32_t i = 0; i < buffersize; i++) {
test_buf[i] = i;
}
for (uint32_t i = 0; i < buffersize; i++) {
if (test_buf[i] != i) {
while (1);
}
}
GPIO_PinWrite(BOARD_Audio_RST_GPIO, BOARD_Audio_RST_PIN, x);
x = !x;
}

Pin toggle is 800ms in my custom board;

https://www.digikey.com/en/products/detail/etron-technology-inc/EM63A165BM-5IH/10321539

This is the SDRAM which i am using.

I tested the same function in this evaluation kit ; https://www.nxp.com/design/designs/nxp-edgeready-smart-hmi-solution-based-on-i-mx-rt117h-with-ml-vis...

and getting 60ms pin toggle time , 

i have same dcd.c and dcd.h files with eval. board,

for both custom board and eval board SDRAM clocks are same = 200MHz 

you can find my clock configuratios on the below picture;

What is the problem? Why my custom board is too slower than eval kit? More thanks for help fron now on.

[MFurkan]

Hello @jingpan

The buffer is located in BOARD_SDRAM section as shown below; 

I would like to run LVGL so the frame buffer should be located here. The capacity of ITCM is not sufficient. I have made the same test on the eval kit speed is 12-13 time better. What could be problem for my custom board?  

[jingpan]

Hi @MFurkan ,

What's the difference in hardware and software?

Regards,

Jing

[MFurkan]

Hi again @jingpan ,

In our custom boards we have following components; 

SDRAM @200MHz;SDRAM which we are using in the custom board

MCU : MIMXRT117HCVM8A  @768 MHz 

For evaluation kit you can refer ; NXP Eval Kit 

Software is almost same with eval kit , so what is the problem with our custom board?

[jingpan]

Hi @MFurkan ,

Maybe the SDRAM is not configured properly. Can you use oscilloscope to measure the SDRAM signal?

Regards,

Jing

[MFurkan]

Hi @jingpan 

I measured both custom board and eval kit SDRAMs with oscilloscope you can see the results on the below; 

194MHz custom board

200MHz eval kit 

Note:My oscilloscope is capable to measure 100MHz signals.

Do you have any suggestion to measure any other signal(s)?

[jingpan]

Hi @MFurkan ,

Is this SEMC_CLK? What's the DQS signal look like? It represent read sequence and speed.

Regards,

Jing

[MFurkan]

Hello again @jingpan 

This is our custom boards DQS signal look like shown below;

Best Regards,

Furkan

[jingpan]

Hi @MFurkan ,

Please enlarge the time window, I need more signal in a screen. Please also add SEMC_CLK signal to another channel.

The interleave of the two DQS is 200ns. So the max speed is 5M word or 20M byte. Please refer to figure 29-12 in reference manual.

Regards,

Jing

[MFurkan]

hi @jingpan 

this is the signals which i catched 

regards,

Furkan

[jingpan]

Hi @MFurkan ,

It looks like there is 4 continue DQS in a read sequence. As I analyze in last reply, it is about 20*4=80M, not too bad. If the burst length is 8, it can be even better.

Maybe there is other problem in your code?

Regards,

Jing

[jingpan]

Hi @MFurkan ,

Where is this test code? You can put this code in ITCM. This can speed up read/write speed.

This is our test report.

Write is far more faster than read. It's because write operation is pipelined, but read operation must wait till SDRAM feedback.

Regards,

Jing