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SDRAM Bandwidth test with the emwin demo

Question asked by hongmei wang on Sep 24, 2019
Latest reply on Oct 2, 2019 by jeremyzhou



I am using the RT1050 EV borad to do the SDRAM performance test. I refer to the AN12437SW firmware which shows how to test the sdram read bandwidth, After run the code on the board, the result was as the document described:

##sdram read perf###t1: 361667; t2: 339695; diff: 21972; ns: 36620, datasize: 4096 byte; perf: 111MB/s; g_ms: 0.


As I was focus on whether the SDRAM bandwidth will be enough for the LCD display, so I port the performance test firmware to the SDK demo: emwin_gui_demo. I comment out all the LCD display related function in main function ,just the sdram read bandwidth test functions was ported. But the result was quite wired, which shows:


##sdram read perf###t1: 369488; t2: 328413; diff: 41075; ns: 68458, datasize: 4096 byte; perf: 59MB/s; g_ms: 0.


Q1.Has there anyone who run to this issue? Why this happens?

Q2.How should I test the SDRAM bandwidth with the LCD display.



Attachment (main funciton in emwin_gui_demo):

int main(void)
uint32_t time;
volatile uint32_t tmp;
uint32_t g_ms;
uint32_t t1;
uint32_t t2;
uint32_t coreclk = 0;
uint32_t dsize = 4*1024;
uint32_t *ahb_addr = (uint32_t *)0x80000000;

coreclk = CLOCK_GetFreq(kCLOCK_CoreSysClk);
CLOCK_InitSysPfd(kCLOCK_Pfd2, 29);
/* Set semc clock to 163.86 MHz */
CLOCK_SetMux(kCLOCK_SemcMux, 1);
CLOCK_SetDiv(kCLOCK_SemcDiv, 1);
#if( DCACHE_ENABLE ==1 )
PRINTF("DCACHE is enabled!\r\n");
PRINTF("DCACHE is disable!\r\n");
PRINTF("Prefetch is disable!\r\n");
PRINTF("Prefetch is enable!\r\n");
if (BOARD_InitSEMC() != kStatus_Success)
PRINTF("\r\n SEMC SDRAM Init Failed\r\n");

PRINTF("\r\n Start test SDRAM read performance!\r\n");
/* sdram read test */
ahb_addr = (uint32_t *)0x80000000;
g_msCount = 0;
t1 = SysTick->VAL;
#if 1
for (uint32_t i = 0; i < dsize/4; i ++)
sdram_readBuffer[i] = ahb_addr[i];
memcpy(&sdram_readBuffer[0],(uint32_t *)(ahb_addr),dsize);
t2 = SysTick->VAL;
g_ms = g_msCount;
time = (((uint64_t)(t1 - t2) * 1000000000) / coreclk);

uint32_t errCount = 0;
for(uint32_t i=0;i<dsize/4;i++)
if(sdram_readBuffer[i] != sdram_writeBuffer[i])
PRINTF("sdram read and write correctly!\r\n");
PRINTF("sdram read and write fail!\r\n");
PRINTF("##sdram read perf###t1: %d; t2: %d; diff: %d; ns: %d, datasize: %d byte; perf: %dMB/s; g_ms: %d\r\n",
t1, t2, t1 - t2, time, dsize, (dsize * 1000)/time, g_ms);

// /* invlide the cache range ahb_addr to ahb_addr+dsize */
DCACHE_InvalidateByRange((uint32_t )ahb_addr,dsize);

PRINTF("\r\n SEMC SDRAM Performance test End.\r\n");

//sdram test
while (1)