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TMS320F28335: flash memory (SST39VF800A) access problem via XINTF

Ahmet Hakan Oğuz
Prodigy 10 points
Part Number: TMS320F28335

Hi,

We have already using DUALPORT RAM and SARAM in our boards. They are working fine via XINTF. 

Now we want to use Microchip Brand Flash Ram which is SST39VF800A. All three memory must work on the board. You can see the timing configuration for all memories. I also configured the GPIOs as shown below. 

However when I looked the flash memory location from Memory Browser, I see all the values of flash memory is equal to 1. I can't change the flash memory values to 0. They always stay at 1. I tried to change the values via memory browser on debug mode. Where could i be doing wrong?

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void ConfigXintf(void)
{
EALLOW;
// XINTF configuration
XintfRegs.XINTCNF2.bit.XTIMCLK = 0; // XTIMCLK = SYSCLKOUT = 150MHz
XintfRegs.XINTCNF2.bit.CLKMODE = 0; // XCLKOUT = XTIMCLK = 150 MHz
XintfRegs.XINTCNF2.bit.CLKOFF = 0; // Enable XCLKOUT
XintfRegs.XINTCNF2.bit.WRBUFF = 0; // No write buffering
XintfRegs.XINTCNF2.bit.HOLD = 1; // Does not grant a request to an external device
// ZONE 0 - Timing for 4k x16 Dualport SRAM Access
XintfRegs.XTIMING0.bit.XWRLEAD = 1; // zone write timing
XintfRegs.XTIMING0.bit.XWRACTIVE = 1;
XintfRegs.XTIMING0.bit.XWRTRAIL = 0;
XintfRegs.XTIMING0.bit.XRDLEAD = 1; // zone read timing
XintfRegs.XTIMING0.bit.XRDACTIVE = 2;
XintfRegs.XTIMING0.bit.XRDTRAIL = 0;
XintfRegs.XTIMING0.bit.X2TIMING = 0; // don't double all zone read/write lead/active/trail timing
XintfRegs.XTIMING0.bit.USEREADY = 0; // does not sample XREADY signal
XintfRegs.XTIMING0.bit.READYMODE = 0; // sample asynchronous
XintfRegs.XTIMING0.bit.XSIZE = 3; // configured for 16-bit mode
// ZONE 6 - Timing for 512k x16 Flash Access
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

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void InitDSPXintf16Gpio()
{
EALLOW;
/* Configure XINTF pins using GPIO regs*/
GpioCtrlRegs.GPCMUX1.bit.GPIO64 = 3; // XD15
GpioCtrlRegs.GPCMUX1.bit.GPIO65 = 3; // XD14
GpioCtrlRegs.GPCMUX1.bit.GPIO66 = 3; // XD13
GpioCtrlRegs.GPCMUX1.bit.GPIO67 = 3; // XD12
GpioCtrlRegs.GPCMUX1.bit.GPIO68 = 3; // XD11
GpioCtrlRegs.GPCMUX1.bit.GPIO69 = 3; // XD10
GpioCtrlRegs.GPCMUX1.bit.GPIO70 = 3; // XD19
GpioCtrlRegs.GPCMUX1.bit.GPIO71 = 3; // XD8
GpioCtrlRegs.GPCMUX1.bit.GPIO72 = 3; // XD7
GpioCtrlRegs.GPCMUX1.bit.GPIO73 = 3; // XD6
GpioCtrlRegs.GPCMUX1.bit.GPIO74 = 3; // XD5
GpioCtrlRegs.GPCMUX1.bit.GPIO75 = 3; // XD4
GpioCtrlRegs.GPCMUX1.bit.GPIO76 = 3; // XD3
GpioCtrlRegs.GPCMUX1.bit.GPIO77 = 3; // XD2
GpioCtrlRegs.GPCMUX1.bit.GPIO78 = 3; // XD1
GpioCtrlRegs.GPCMUX1.bit.GPIO79 = 3; // XD0
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

  • +1
    TI__Guru* 95315 points

    Ahmet,

                    Flash works very differently compared to RAM. While you can change any bit in RAM any way you want anytime you wish, it is not so simple with Flash. Flash memory uses a very different technology compared to RAM, which is what gives us the benefit of non-volatility. In the erased state, all bits in Flash are 1. Programming operation is where chosen bits are flipped to 0. Depending on the technology used to manufacture the Flash chip, a very specific sequence needs to be followed to program the flash (this is described in page 7 of the SST39VF200 datasheet). While we use the word "write" for RAM, we generally use the word "program" for flash. You can change the value of a bit from 1 to 0 but not the other way around. Also, you need to erase the flash before you can program it. Generally, you cannot erase a single byte/word; you need to erase an entire sector. Please go through the flash chip's datasheet very carefully. 

    Ahmet Hakan Oğuz said:
    I see all the values of flash memory is equal to 1.

    That is very likely because the flash chip is in an erased state.

    Ahmet Hakan Oğuz said:
    I can't change the flash memory values to 0. They always stay at 1

    You need to follow the specific sequence to erase/program the device.

    Ahmet Hakan Oğuz said:
    I tried to change the values via memory browser on debug mode.

    That will not work, for the reasons I already explained.