Подключаем 3,3V SDRAM к LPC3250 Опции

[V_TC]

Здравствуйте, уважаемые форумчане!
Помогите разобраться с подключением SDRAM к LPC3250. В доступных примерах подключения для питания SDRAM (или DDR SDRAM) используется напряжение 1,8 или 2,5В. Однако напряжение 3,3В для питания SDRAM заявлено в даташите как допустимое. Используем память MT48LC16M16A2BG-75IT при питании 3,3В. Схема подключения SDRAM к LPC3520 -

[-= Александр =-]

В общем устал тыркаться - взял какой-то пример - и все заработало! Дальше буду его ковырять....

Код

void SDRAMInit( void )
{
  DWORD i, dummy = dummy;

  /*************************************************************************
  * Initialize EMC and SDRAM
  *************************************************************************/
//  SCS     |= 0x00000002;        /* Reset EMC */
  EMC_CTRL = 0x00000001;        /*Disable Address mirror*/
  PCONP   |= 0x00000800;        /* Turn On EMC PCLK */
  PINSEL4  = 0x50000000;
  PINSEL5  = 0x05050555;
  PINSEL6  = 0x55555555;
  PINSEL8  = 0x55555555;
  PINSEL9  = 0x50555555;  
  
  EMC_DYN_RP     = 2;        /* command period: 3(n+1) clock cycles */
  EMC_DYN_RAS    = 3;        /* RAS command period: 4(n+1) clock cycles */
  EMC_DYN_SREX   = 7;        /* Self-refresh period: 8(n+1) clock cycles */
  EMC_DYN_APR    = 2;        /* Data out to active: 3(n+1) clock cycles */
  EMC_DYN_DAL    = 5;        /* Data in to active: 5(n+1) clock cycles */
  EMC_DYN_WR     = 1;        /* Write recovery: 2(n+1) clock cycles */
  EMC_DYN_RC     = 5;        /* Active to Active cmd: 6(n+1) clock cycles */
  EMC_DYN_RFC    = 5;        /* Auto-refresh: 6(n+1) clock cycles */
  EMC_DYN_XSR    = 7;        /* Exit self-refresh: 8(n+1) clock cycles */
  EMC_DYN_RRD    = 1;        /* Active bank A->B: 2(n+1) clock cycles */
  EMC_DYN_MRD    = 2;        /* Load Mode to Active cmd: 3(n+1) clock cycles */

  EMC_DYN_RD_CFG = 1;        /* Command delayed strategy */

  /* Default setting, RAS latency 3 CCLKs, CAS latenty 3 CCLKs. */
  EMC_DYN_RASCAS0 = 0x00000303;

#if ENG_BOARD_LPC24XX        /* NXP engineering board */
  /* 256MB, 16Mx16, 4 banks, row=12, column=9 */
  EMC_DYN_CFG0 = 0x00000480;
#else                        /* Embedded Artists board */
  /* 256MB, 16Mx16, 4 banks, row=13, column=9 */
  EMC_DYN_CFG0 = 0x00000680;
#endif
  delayMs(1, 100);            /* use timer 1 */

  /* Mem clock enable, CLKOUT runs, send command: NOP */
  EMC_DYN_CTRL = 0x00000183;
  delayMs(1, 200);            /* use timer 1 */
    
  /* Send command: PRECHARGE-ALL, shortest possible refresh period */
  EMC_DYN_CTRL = 0x00000103;

  /* set 32 CCLKs between SDRAM refresh cycles */
  EMC_DYN_RFSH = 0x00000002;
  for(i = 0; i < 0x40; i++);    /* wait 128 AHB clock cycles */
    
  /* set 28 x 16CCLKs=448CCLK=7us between SDRAM refresh cycles */
  EMC_DYN_RFSH = 28;
    
  /* To set mode register in SDRAM, enter mode by issue
  MODE command, after finishing, bailout and back to NORMAL mode. */    
  /* Mem clock enable, CLKOUT runs, send command: MODE */
  EMC_DYN_CTRL = 0x00000083;
  
  /* Set mode register in SDRAM */
  /* Mode regitster table for Micron's MT48LCxx */
  /* bit 9:   Programmed burst length(0)
     bit 8~7: Normal mode(0)
     bit 6~4: CAS latency 3
     bit 3:   Sequential(0)
     bit 2~0: Burst length is 8
     row position is 12 */
  dummy = *((volatile DWORD *)(SDRAM_BASE_ADDR | (0x33 << 12)));
  
  EMC_DYN_CTRL = 0x00000000;      /* Send command: NORMAL */

  EMC_DYN_CFG0 |= 0x00080000;      /* Enable buffer */
  delayMs(1, 1);                  /* Use timer 1 */
  return;

}