The speed of RT1052 to read data from SDRAM noncache area is very slow

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The speed of RT1052 to read data from SDRAM noncache area is very slow

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longxing
Contributor III

I need to read data from SDRAM noncache area.the SDRAM is simulated using FPGA,and it contains ADC result,so it must have noncache attribute.

The problem is that it consumes about 1.5us to read 10 uint16_t data.Using FPGA to monitor data transfering on the bus,it shows like the picture belowread.png

There are about 26 clocks between two read operation,and during this period,the bus is idle.My CPU works at 528MHz,and SEMC works at 132MHz。

The disassember code that read data from FPGA is listed below:

mov.w r3,0x84000000
add.w r4,r7,#8
mov   r5,r3
ldr   r0, [r5, #0]
ldr   r1, [r5, #4]
ldr   r2, [r5, #8]
ldr   r3, [r5, #12]
stmia r4!,{r0,r1,r2,r3}
ldr   r0,[r5,#16]
str   r0,[r4,#0]

This code segment locates in the highest priority ISR,There is no  possible to be interrupted.

why are there 26 clocks between two read operation?How can i promote reading speed?

Any suggestion is appreciated!

Thanks in advance.

Best regards!

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