reading and writing SRAM from CCS v3.3 using emulator XDS510USB Plus

Hi Barry,

Are you configuring the EMIF for SRAM in your code or you are using GEL file to configure EMIF. Since you are loading your code to SRAM I guess you will use GEL for configuring the EMIF. In that case make sure that SRAM initialization function(SRAM_INIT or something like that) in the GEL file is being called. You can invoke the SRAM/EMIF initialization function in the GEL file using the CCS GEL menu. Otherwise you can add the SRAM/EMIF init function call in OnTargetConnect() in the GEL file so that your EMIF will be configured during the target connection.

Pratap.

Hi Pratap,

I first tried to download my code using CCS. I got a memory verification error. I then decide to try to read and write into my off chip SRAM which is located at 0x600000 (word address). I could not write properly to every other location starting with the first one.

I looked at the GEL menu in CCS and found that it had a SDRAM initialization but not one for SRAM. I assume this means I have to add an EMIF call to the GEL file to setup the interface to the specific SRAM I am using before I can read and write to. Is this correct?

Barry,

If the EMIF registers for the CE space on which your SRAM is located are not configured correctly then there is no telling how the SRAM will react. As you implied you will need to create a small routine in the GEL file to configure the EMIF for your SRAM (initSram() or something like that).

Let me know if you have questions about how to do this. It is fairly similar to coding in C, and you should be able to model if off something like the SDRAM initialization function.

Hi Baryy,

RESER_CONTROL is Peripheral Reset Control Register. In SDRAM_INIT it is configured to reset the EMIF. Same configuration holds good for SRAM also. You can find the details of this register in DSP system user guide.

You have to configure EMIF 'Asynchronous Wait Cycle Configuration Registers' and 'Asynchronous CSn Configuration Registers' for initializing the SARAM

Pratap. 

Pratap

I am still having problems accessing my off chip SRAM (location 0x600000 word address – 2 megabyte).I have created a routine in my  GEL file that initializes the AWCCR1, AWCCR2, ACS3CR1, and the ACS3CR2 registers. I placed the call to it in the function OnTargetConnect in the GEL file. I see the SRAM message when I connect to the target. When I write 0x1234 to the first, third, etc..  locations the value 0x3434 is stored there. When I write 0x5678 to the second, fourth, etc…  locations the value 0x78 is store there.

The code I wrote is as follows:

#define SRAM_Async_Wait_Reg_1         0x1004

#define SRAM_Async_Wait_Reg_2         0x1005

#define SRAM_Async_CS3_Reg_1           0x1014

#define SRAM_Async_CS3_Reg_2           0x1015

menuitem "SRAM_Configuration";

hotmenu SRAM_INIT() {

    *(short *)RESET_CONTRL@IO = 0x0002;

    *(short *)SRAM_Async_Wait_Reg_1@IO = 0x0080;

    *(short *)SRAM_Async_Wait_Reg_2@IO = 0x4030;

    *(short *)SRAM_Async_CS3_Reg_1@IO = 0x4520;

    *(short *)SRAM_Async_CS3_Reg_2@IO = 0x0031;

    GEL_TextOut("SRAM Initilization Complete.\n");

}

I put the call to SRAM_INIT in OnTargetConnect so I could see the message in the CCS box. I do not know much about the interface to SRAM and have no one here that does. Several of the values placed in the registers were arbitrarily picked around the midpoint of the range for the entry. I would appreciate any suggestions.

Thanks

Barry

Hi Barry,

Try with the configuration *(short *)SRAM_Async_CS3_Reg_1@IO = 0x4521;

Pratap.

Barry,

Click on the CCS menu 'View' and select 'Memory'. A memory window will be opened on the right side of the CCS. At the bottom of the memory window In the second drop down menu select 'IO' and enter 0x1c33 in the filed that shows 'Enter An Address'.

Pratap.  

Pratap

The value stored there is 0x0002. I read that on reset the EMIF should be set to 16 bit. I am trying to find what the value stored there (0x0002) means.

Thanks

Barry