SDRAM Mode register configuration

andreascauri — Thu, 02 Aug 2018 10:50:24 GMT

Hello.

I have a problem during initialization of the SDRAM with set mode register :

wtemp =*(volatile unsigned int *)(DYNAMIC_MEM0_BASE+(MODE_REGISTER << (COL+TBW+BANK)));

sometime the execution block in this code line so much to trigger watchdog.

Does anyone have any idea what it could be?

SDRAM: MT48LC16M16A2P-75

MPU: LPC1778

Complete SDRAM init code

uint32_t i, wtemp;

DbgUart2("> %s\n",__FUNCTION__);

SCS &=~BIT(1); //EMC reset when any resert occures // era EMC Shift Control

PCONP |= PCONP_PCEMC; // BIT(11); // Turn ON EMC PCLK

//EMC_DYN_RD_CFG = 0; // michele

EMCDLYCTL=0x00001010;

// Init SDRAM controller
EMC_CTRL = 1;// enable EMC
EMC_CONFIG = 0;

EMC_DYN_CFG0= ( (0uL << 14) | (0uL << 12) | (Sel9 << 9) | (Sel7 << 7));

/*Dynamic Memory RAS & CAS Delay registers
* 3 CAS PCLK cycles
* 3 RAS PCLK cycles
*/
EMC_DYN_RASCAS0 = (CAS << CAS_BIT) | (3uL << RAS_BIT);

//EMCDynamicReadConfig
EMC_DYN_RD_CFG = 1;

/*
* Dynamic Memory Percentage Command Period register
* The EMCDynamicTRP register enables you to program the precharge command period,
* tRP. This register must only be modified during system initialization. This value is normally
* found in SDRAM data sheets as tRP. This register is accessed with one wait state
*/
EMC_DYN_RP = P2C(SDRAM_TRP); // EMCDynamictRP
EMC_DYN_RAS = P2C(SDRAM_TRAS); // EMCDynamictRAS
EMC_DYN_SREX = P2C(SDRAM_TXSR); // EMCDynamictSREX Self Refresh Exit Time
EMC_DYN_APR = SDRAM_TAPR; // EMCDynamictDAL // Last Data Out to Active Time
EMC_DYN_DAL = SDRAM_TDAL + P2C(SDRAM_TRP); // Data in to Active Command Time
EMC_DYN_WR = SDRAM_TWR; // EMCDynamictWR // Write Recovery Time
EMC_DYN_RC = P2C(SDRAM_TRC); // EMCDynamictRC // Active to Active command Period
EMC_DYN_RFC = P2C(SDRAM_TRFC); // EMCDynamictRFC // Auto Refresh Period
EMC_DYN_XSR = P2C(SDRAM_TXSR); // EMCDynamictXSR // Exit Self Refresh
EMC_DYN_RRD = P2C(SDRAM_TRRD); // EMCDynamictRRD // Active Bank A to Active Bank B Time
EMC_DYN_MRD = SDRAM_TMRD; // EMCDynamictMRD = SDRAM_TMRD; // Load mode register to Active Command Time

Delay_uS(100*MSEC);

//Send command: NOP
EMC_DYN_CTRL = 3 | (3<<7);

// Mem clk enable, CLKOUT runs, send command: NOP
Delay_uS(200*MSEC);

//Send command: PRECHARGE-ALL, shortest possible refresh period
EMC_DYN_CTRL = 3 | (2<<7);
EMC_DYN_RFSH = 0x00000002;

//wait at least 128 ABH clock cycles
for(i=0; i<0x80; i++)
asm volatile(" nop");
//Delay_uS(100*MSEC);

/*
* Some systems refresh every row in a burst of activity involving all rows every 64 mS.
* Other systems refresh one row at a time staggered through out the 64 mS interval.
* For example, a system with 2^13 = 8192 rows would require a staggered refresh rate of one row
* every 7.8 µs which is 64 ms divided by 8192 rows
*/

/* set 28 x 16CCLKs=448CCLK=7us between SDRAM refresh cycles */
EMC_DYN_RFSH = P2C(SDRAM_REFRESH) >> 4;

DbgUart2("1 WDTC: %d, TV %d \n", WDTC, WDTV);

/* To set mode register in SDRAM, enter mode by issue
MODE command, after finishing, bailout and back to NORMAL mode. */

//Send command: MODE
EMC_DYN_CTRL = 3 | (1<<7);

DbgUart2("2 WDTC: %d, TV %d \n", WDTC, WDTV);
/* 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

You may calculate the shift value for "high-performance" SDRAM using this
formula:
SHIFT_HIGH_PERFORMANCE = COL + TBW + BANK, where
COL=# of column bits (here: 9)
TBW=total bus width, 1=16 bits, 2=32 bits (here: 2)
BANK=# of bank select bits (here: 2)
Just for completeness: For "low-power" SDRAM leave out the BANK term:
SHIFT_LOW_POWER = COL + TBW
*/

//Delay_uS(100*MSEC);
wtemp =*(volatile unsigned int *)(DYNAMIC_MEM0_BASE+(MODE_REGISTER << (COL+TBW+BANK)));

DbgUart2("3 WDTC: %d, TV %d \n", WDTC, WDTV);

EMC_DYN_CTRL = 0x00000000; /* Send command: NORMAL */

//Enable buffer
EMC_DYN_CFG0 |= BIT(19);

/* Abilito la ethernet per accedere alla 16K di ram */
//PCONP |= BIT(30);

DbgUart2("%s <\n",__FUNCTION__);

Re: SDRAM Mode register configuration

jeremyzhou — Mon, 06 Aug 2018 02:05:49 GMT

Hi Andrea Scauri,
Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
To provide the fastest possible support, I'd highly recommend you to refer to the periph_memtest demo in LPCOpen library to adjust the SDRAM initialization code, then taking a testing later.

LPCOpen Software for LPC17XX|NXP
Have a great day,
TIC

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SDRAM Mode register configuration

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