We are working on new design about CPU card which include core cortex M3 LPC1850FET180.

We meet a problem.

Description of ours system
THE CPU is composed of :
1 Microcontrôler : LPC1850FET180
1 Spifi flash : S25FL032P (4 M) (code)
1 SDRAM : MT48LC4M16A2P_6A (8 M)
1 Flash parallel 32Mb: SST39VF3201B-70
Driving of display LCD TFT 5,7” (640 X 480)
Display memory LCD 0x28000000-0x28258000 (SDRAM)
Graphics library emWin SEGGER V.530 for NXP
We use double buffer to avoid Flickering effects.

But display flicker while displaying the image(GUI_DrawBitmap(&bmCB01, 0, 0)) ?

code:
#define COLOR_CONVERSION GUICC_888
#define DISPLAY_DRIVER GUIDRV_LIN_OSY_32
#define NUM_BUFFERS 2
#define NUM_VSCREENS 1

GUI_Init();
WM_MULTIBUF_Enable(1);
while(1){
GUI_MULTIBUF_Begin();
GUI_DrawBitmap(&bmCB01, 0, 0);// LCD flicker !
GUI_MULTIBUF_End();
GUI_Delay(2000);// LCD ok
GUI_MULTIBUF_Begin();
GUI_DrawBitmap(&bmCB02, 0, 0);//LCD flicker
GUI_MULTIBUF_End();
GUI_Delay(2000);//LCD ok
}

Kindly give any suggestion.