What is wrong with my code ??

[afesheir]

hi everybody ..
I hope I find my needs in this great board ..
Now I am trying to initialize MMC SanDisk 1GB using my own code (without using mikroC library) with PIC16F877A ..

When the card is initialized, I want my GLCD to display the word "Ready", otherwise I want to display "Initializing ..." ..

before anything, I want to display "WELCOME" ..

the GLCD is functioning properly alone, but with my code, the glcd displays nothing ..

here is my code:

//module connection

char GLCD_DataPort at PORTD;
sbit GLCD_CS1 at RB0_bit;
sbit GLCD_CS2 at RB1_bit;
sbit GLCD_RS  at RB2_bit;
sbit GLCD_RW  at RB3_bit;
sbit GLCD_EN  at RB4_bit;
sbit GLCD_RST at RB5_bit;
sbit GLCD_CS1_Direction at TRISB0_bit;
sbit GLCD_CS2_Direction at TRISB1_bit;
sbit GLCD_RS_Direction  at TRISB2_bit;
sbit GLCD_RW_Direction  at TRISB3_bit;
sbit GLCD_EN_Direction  at TRISB4_bit;
sbit GLCD_RST_Direction at TRISB5_bit;


// Software SPI module connections
sbit SoftSpi_SDI at RC4_bit;
sbit SoftSpi_SDO at RC5_bit;
sbit SoftSpi_CLK at RC3_bit;

sbit SoftSpi_SDI_Direction at TRISC4_bit;
sbit SoftSpi_SDO_Direction at TRISC5_bit;
sbit SoftSpi_CLK_Direction at TRISC3_bit;
// End Software SPI module connections


void sendCommand(int cmdIndex);        //function prototype

void main() {
     unsigned char Response;


     Soft_SPI_Init(); // Init Soft_SPI
     Glcd_Init();     //Init. GLCD
//     Glcd_Set_Font(font5x7 , 5, 7, 32);// Change font
     Glcd_Fill(0x00); //Clear GLCD
     Glcd_Write_Text("WELCOME",0,0,1);


     TRISC.B1=0;    //Make RC2 output pin (CS or SS Pin)
     PORTC.B1=0;      //Hold CC=0
     delay_ms(4);     //Delay about 75 clock pulses at 20KHz

     sendCommand(0x00);   //CMD0 for S/W reset
Init:sendCommand(0x37);   //CMD55 to tell that the next command is Application Specific
     sendCommand(0x29);   //ACMD41 to Initialize the SD Card
     Response= Soft_Spi_Read([b][color=red]0x00[/color][/b]);

     if (Response==0x00)
     {
        Glcd_Fill(0x00);         //Clear GLCD
        Glcd_Write_Text("Ready !!",20,4,1);

     }
     else
     {
        Glcd_Fill(0x00);
        Glcd_Write_Text("Initializing ...",20,4,1);
        goto Init;
     }

}

void sendCommand(int cmdIndex)
{
     Soft_Spi_Write(0x40+cmdIndex);  //Send command of index cmdIndex
     Soft_Spi_Write(0x00);         //Send 4
     Soft_Spi_Write(0x00);         //Clear Bytes
     Soft_Spi_Write(0x00);         //As
     Soft_Spi_Write(0x00);         //Argument
     Soft_Spi_Write(0x95);         //CRC = 0x95 for CMD0 and not important for SPI mode
}

also I am asking about the red number, this function is to read data from spi bus, why do we need to assign data to send ..?

Great thanks to everybody ..

 

[afesheir]

hay everybody .. I am in bad need to solve this bug !!

 

[betwixt]

SPI transfers data in both directions on each clock pulse. There is no way of reading without a simultaneous write occurring. When only reading, any data can be placed on the outgoing wire but obviously you don't want it to be interpreted as a command so a 'do nothing' byte, 0x00 in your case, is used.

Brian.

 

[afesheir]

thx betwixt .. I got it ..
also the GLCD now works fine .. it displays texts well ..
But is my code for MMC/SD initialization true .. I can't get the message "Ready" that indicates that the SD has been sucessfully initialized ..

As a troubleshooting technique, I want the GLCD to display the value of the response .. how can I do that ??

thx everybody >>>> up up >>

 

[betwixt]

I'm guessing: If the response is not zero, you send initialization again without delay. Perhaps you should send initialization data then loop a few times to give the card chance to reply.

Brian.

 

[afesheir]

thanks mate .. I tried ur solution and it worked fine .. great thanks ..