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Before using DMA, make sure that the EMIF is programmed properly. This is accomplished through the use of the following registers:

Asynchronous Wait Cycle Configuration Register 1

Asynchronous Wait Cycle Configuration Register 2

Asynchronous CS2 Configuration Register 1

Asynchronous CS2 Configuration Register 2

These registers configure the EMIF's setup, strobe, hold, wait, and turn around time of each external access in terms of CPU clock cycles. It also sets the data bus width for the corresponding chip select. Once these are configured to match the timings of your NOR, the DMA should be able to read and write to NOR.

Pedro,

I am configuring the registers you mentioned as follows:

    /* Config EMIF - ASYNC-Wait Config Registers */
    EMIF_AWCCR1      = 0x00FF;  // to set the MEWC field to maximum 0xFF;
    EMIF_AWCCR2      = 0x00E4;  // bits 8 to 15 still remain non-zero

    EMIF_ACS2CR1    |= 0x000D;  // Asynchronous data bus 16-bit width and
                                                         // and Minimum turn-around time set to max 3.    

    EMIF_ACS2CR2    |= 0x4000;  // bit 14 is tried to be set to '1' in order to enable the Extended wait cycles

                                                         // however bit 14 does not become '1' after this instr.

I do not know what other bits to set. I am referring to "SPRUGU6–March 2010 External Memory Interface (EMIF)"  document.

When I execute the code, only every eighth  word is correctly written to external  NOR flash as is illustrated below:

Please note that for the present I only want to get the writing to NOR flash via DAM to be done perfectly.

Also the buffer that I am using to send the external memory is:

00A0   0005  00A0 0007  00A0 0009 00A0 000B 00A0 000D 00A0 000F 00A0 0011  00A0 0013 00A0 0015 00A0 0017 ....

The NOR flash is then reset to all FFFFs as:

FFFF  FFFF  FFFF  FFFF  FFFF  FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF ...

And the data that is transferred to the external NOR using DMA is :

FFFF  0005  FFFF  FFFF FFFF FFFF FFFF FFFF FFFF 000D  FFFF FFFF FFFF FFFF FFFF FFFF FFFF 0015 FFFF FFFF

Thus only every eighth word is transferred.

Note that the buffer has 00A0 every alternate word since the NOR flash needs this to be able to write the next word.

Thus please give me further hints and clues what to do since I need to be able to write to NOR flash using DMA.

Thanks in advance.

- AV

Hi,

Are you able to write to the NOR flash with out using DMA?. Are you sure that your flash needs only 00A0 for writing a word?. Most of the Spansion NOR flash chips require a specific command sequence(0xAA, 0x55, 0xA0) for programming a word. Please verify the NOR read and write operations with out using DMA to make sure that your EMIF and other configurations are fine. Then making the write operation work with DMA becomes easy. Check if your NOR flash supports command to write multiple words, this command is more suitable for DMA operation.

Pratap. 

Yes I am able to read and write to NOR flash without DMA.

I am also able to read from NOR flash with DMA.

Writing to NOR flash with DMA is the issue. Pratap, Have you ever been able to do it ?

There is a Unlock Bypass Mode wherein after you unlock the NOR flash then it is only required to send 00A0 before every word to be written.

Regds,

- AV.

Hi,

As answered to your email, DMA to NOR can not be done that simple. When DMA starts, it keeps writing to NOR and it's checking the writing finished.

Can you tell me why you want to use DMA write to NOR?

Regards,

Hyun 

Pedro,

As mentioned by you, part of programming the EMIF porperly is to configure the Asynchronous CS2 Configuration Register 2.

Now this is an I/O register at location 0x001011. The MSB of this register cannot be edited by programming nor by View -> Memory and physically

 changing the value. If writing to the NOR flash using DMA is to be done then this has to be looked at and resolved.

I am using the USB ezDSP stick 5515. Code composer studio Version: 4.1.3.00038 and Code Generation Tool 4.3.5.

Thanks and regards,

AV.

Hi,

Please check the configuration of "EMIF System Control Register (ESCR) [1C33h]" in your program.

You need to set this register to word access to allow the CPU to access 16 bits of the EMIF registers.

Pratap.

Pratap,

Thanks for your solution.

However the bigger problem does remain, that is, still I am not able to write data to the external NOR flash using DMA.

Only every eight word is getting stored.

Regds,

AV