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SSP1 Problem - Serial Mem. Communication

Fabio Afellay

Hi u all!

I'm facing a problem here, I'm trying to develop a serial flash memory interface here.
The memory is M25P128, and I'm using LPC2368.

The thing is..I don't have much experience with SPI/SSP.
Well.. I've downloaded some examples but I couldn't establish the communication appropriately.
Ideally I should have an oscilloscope to check all this, but..

The following code just try to request from the memory its status register:

int InitSSP()
{
        PCONP = 1<<10;
        PINSEL0 = 0xA8000;
        PINMODE0 = 0xA8000;// Here is my first doubt, the pins should be configured with pull-up or not?

        //INTERRUPT
        VICVectAddr11 = (unsigned long) SSP_Isr;
        VICVectCntl11 = 0;
        VICIntEnable |= 0x800; // 11th bit is the SSP1

        FIO2DIR1 = (1<<3); //SS Pin - configured as output

        SSP1CR1 = 0;//SSP disable
        SSP1CR0 = 0x07;
        SSP1CPSR= 10;
        SSP1IMSC = 3;//Receives int
        SSP1CR1 = 2;

}

void SSP_Isr(void) __irq
{
        spiBuf[0] = SSP1DR;
        VICVectAddr = 0; // reset VIC
        FIO2PIN1  = 1<<3;//HIGH
}

int WriteFlash()//Adress, Data, size
{

    FIO2PIN1  = 1<<3;     //HIGH
    FIO2PIN1  = 0<<3;     //LOW

    SSP1DR = 0x05; //Instrução WREN
    while (!(SSP1SR & SSPSR_BSY));

    //FIO2PIN1  = 1<<3;   //HIGH - In this test I set the High signal in the interruption method because it should be set after receive the message from the memory

}

The problem is, doesn't matter which instruction I send I still receive answers that doesn't make any sense! And should be just a few specific instructions that the memory should answer back.

thanks

Parents
  • 0 in reply to Fabio Afellay

    To get 64 bits from the card to the processor, the card needs to see 64 clocks on the SPI clock line (while the card also sees the slave select signal active).

    So how do you get 64 clock ticks on the clock signal? Exactly - by sending 64 bits of dummy data to the card. It is the master that owns the clock signal, and the master must transmit to be able to receive. And it will always receive when it is transmitting.

    In this case, you should probably send 8 bytes of 0xff (if the idle state of the data lines are expected to be high) to generate a 64-bit dual-direction transfer. Dummy data to the memory chip and read data from chip to processor.

Reply
  • 0 in reply to Fabio Afellay

    To get 64 bits from the card to the processor, the card needs to see 64 clocks on the SPI clock line (while the card also sees the slave select signal active).

    So how do you get 64 clock ticks on the clock signal? Exactly - by sending 64 bits of dummy data to the card. It is the master that owns the clock signal, and the master must transmit to be able to receive. And it will always receive when it is transmitting.

    In this case, you should probably send 8 bytes of 0xff (if the idle state of the data lines are expected to be high) to generate a 64-bit dual-direction transfer. Dummy data to the memory chip and read data from chip to processor.

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