Hi,

Im having problems setting up a pair of 128Mb SDRAMs (MT48LC8M16A2) to work with my custom AT91RM9200 board (The RAM modeule is the same as the one used on the DK) . I am relying on the debug unit to send back the read value to HyperTerminal.
(Seems like the SDRAM is not holding on to the data)

Below is my initialization code:

Code:
+++++++++++++++++++++++++

int i;
int *pSDRAM = (int *)BASE_EBI_CS1_ADDRESS;

//* Configure PIOC as peripheral (D16/D31)
AT91F_SDRC_CfgPIO();

//* Setup MEMC to support CS1=SDRAM
AT91C_BASE_EBI->EBI_CSA |= AT91C_EBI_CS1A;
AT91C_BASE_EBI->EBI_CFGR = 0;

//* Init SDRAM

AT91C_BASE_SDRC->SDRC_CR =
0x01 |//NC=9 columns
0x04 |//NR=12 rows
0x08 |//NB=4 banks
0x40 |//CAS=4
0x100 |//TWR=2
0x2800 |//TRC=5
0x10000 |//TRP=2
0x180000 |//TRCD=3
0x2800000 |//TRAS=5
0x28000000 //TXSR=5
;

//* 2. A Precharge All command is issued to the SDRAM
AT91C_BASE_SDRC->SDRC_MR = AT91C_SDRC_MODE_PRCGALL_CMD;
*pSDRAM = 0;

//* 3. Eight Auto-refresh are provided
AT91C_BASE_SDRC->SDRC_MR = AT91C_SDRC_MODE_RFSH_CMD;
for(i=0;i<7;i++)
*pSDRAM = 0;

//* 4. A mode register cycle is issued to program the SDRAM parameters
AT91C_BASE_SDRC->SDRC_MR = AT91C_SDRC_MODE_LMR_CMD;
*(pSDRAM+0x80) = 0;

//4.5 Three NOPs to take care of tMRD
AT91C_BASE_SDRC->SDRC_MR = AT91C_SDRC_MODE_NOP_CMD;
for(i=0; i<2; i++)
*pSDRAM = 0;


//* 6. A Normal Mode Command is provided, 3 clocks after tMRD is set
//Normal Mode, 32 bit word length
AT91C_BASE_SDRC->SDRC_MR = 0x0;
*pSDRAM = 0;

//* 5. Write refresh rate into SDRAMC refresh timer COUNT register
AT91C_BASE_SDRC->SDRC_TR = (AT91C_SDRC_COUNT & 0x2E0);//4096 refresh cycles every 64ms
*pSDRAM = 0;

=================================================
this is how im checking the SDRAM:


volatile char *base = (char *)0x20000000;
volatile int *base2 = (int *)0x20000000;

char buf[10];

*base2 = 0xAABBCCDD;

sprintf( buf, "%x\r\n", *(base2));
AT91F_DBGU_Printk( buf );
AT91F_DBGU_Printk( "\r\n=============\r\n" );

sprintf( buf,"\r\n%x\r\n", *(base2));
AT91F_DBGU_Printk( buf );

++++++++++++++++++++++++++++++++++++++
As you can see, im reading the same location twice..to check whether the RAM is

"holding on" to the data;turns out that its not;
++++++++++++++++++++++++++++++++++++++

Output:

aabbccdd
=============
ffffffff

++++++++++++++++++++++++++++++++++++++

The second read of the same location does not find anything..also, if i put a delay between the write and the read, i find nothing!

Code:
++++++++++++++++++++++++++++++++++++++
*base2 = 0xAABBCCDD;

delay();
sprintf( buf, "%x\r\n", *(base2));
AT91F_DBGU_Printk( buf );
++++++++++++++++++++++++++++++++++++++

Output:
ffffffff

++++++++++++++++++++++++++++++++++++++

Looks like a problem with the refresh rate...but ive checked and rechecked
everything! Help!

Could it be a problem with the hardware (i mean, the board, not the ram chips.)

Thanks in anticipation
Mayank