AVR Freaks

Thanks. I have the IRQ, P9 connected to 10Kohm to supply voltage and the Com, WP, CD left open.

I have a question regarding setting clock to 400 KHz. The AT169 data sheet suggests using CLKPS[0-3] to divide the default clock frequency. However, I need a divider of 20 (8MHz/20 = 400 KHz), but CLKPS divides in powers of 2 (1, 2, 4, 8, ...)

I have posted this on avr-forums. Also, I am trying to get some code working on butterfly with SD card interface. If it works, I would like to attach it to the tutorial ?

-sid

I have the following code currently as per the tutorial. However, it does not work with the AVR-Butterfly:

+-----------------------------
#define SD_PORT PORTE
#define SD_DDR DDRE
#define SD_SPI_CS PE4 //Use PE4 as chip sel

#define SD_SPI_PORT PORTB
#define SD_SPI_DDR DDRB
#define SD_SPI_SS PB0
#define SD_SPI_SCK PB1
#define SD_SPI_MOSI PB2
#define SD_SPI_MISO PB3

void SPI_Init(void) {
uint8 dummy, i;

SBI(SD_SPI_DDR, SD_SPI_SS); // set PB0 as op
SBI(SD_SPI_PORT, SD_SPI_SS); // set PB0 to 1
SBI(SD_SPI_DDR, SD_SPI_SCK);
SBI(SD_SPI_DDR, SD_SPI_MOSI);
CBI(SD_SPI_DDR, SD_SPI_MISO);
SBI(SD_DDR, SD_SPI_CS);
SBI(SD_SPI_PORT, SD_SPI_CS);

SBI(SPCR, MSTR); // Master
CBI(SPCR, CPOL); // CPOL, CPHA = 0, 0 => mode0
CBI(SPCR, CPHA);
CBI(SPCR, SPR0); // Fosc/64 ~ 125 KHz
SBI(SPCR, SPR1);
CBI(SPCR, DORD);
CBI(SPCR, SPIE); // No SPI interrupt enable
SBI(SPCR, SPE); // Write to SPCR

dummy = SPSR;
dummy = SPDR;
}

char SPI_byte(char c) {
char rcv = 0, i;
SPDR = c;
//while (!(inb(SPSR) & (1<<SPIF)));
loop_until_bit_is_set(SPSR, SPIF);
rcv = SPDR;
i = SPSR;
return rcv;
}

char SD_Init(void) {
unsigned int i;
char rcv;

SBI(SD_PORT, SD_SPI_CS); //Deselect SD
for (i = 0; i < 10; i++)
rcv = SPI_byte(0xff);
Delay(1);
CBI(SD_PORT, SD_SPI_CS); //Select SD

SPI_byte(0x40);
SPI_byte(0x00);
SPI_byte(0x00);
SPI_byte(0x00);
SPI_byte(0x00);
SPI_byte(0x95);

for (i = 0; i < 10; i++)
if((rcv = SPI_byte(0xff)) != 0xff)
break;
SBI(SD_PORT, SD_SPI_CS);

return rcv;
}

main() {
char buf[32], c;

CLKPR = (1<<CLKPCE);
CLKPR = (0<<CLKPS1)|(0<<CLKPS0); //clk = 8MHz
UART_Init();
LCD_Init();
SPI_Init();

c = SD_Init();
if (c == 0x01) {
} else {
sprintf(buf, "%d\n", c);
UART_Puts("fail\n");
UART_Puts(buf);
}
while(1);
}
+----------------------------------------------

When I run the code above, SD_init returns -1 (255). Not sure if there is something wrong with the code. I have the SD card connected to sparkfun.

-sid

hi..could you please tell me if the same procedure applies to interfacing an sd card to atmega32??? I am finding it really difficult to interface the sd card alone..leave the other peripherals.

i am working on interfacing an SD card to an ATMEGA32 . This setup needs to be used in a data acquisition system such that a certain parameter needs to be polled and logged every minute, the log being stored onto the SD card. something like one text file for each day containing that day's log for every minute. As i understand it, I have broken this up into 2 steps:

1)the task of acquiring data and storing it as a text file(using an ASCII header to indicate it to be a text file)

2)sending this data into the SD card and storing it in such a way that when used with a PC, the SD card folder contains text files containing a particular days readings for each minute.

please let me know if this can be implemented? if so, what is the easiest method to acheive it??

I have interfaced an atmega32 to a 1GB SD card(Transcend). I can write and read a single block of data(=512 bytes) successfully. The problem comes when I try to read multiple blocks. No matter what I do, I am getting "CMD18 error". Could you please suggest a feasible solution?
Here's that chunk of code which is causing troubles..

CMD18();
for(i=0;i<50;i++)
{
if(SPI(0x0FF)==(char)0x00)
{
usart_puts("CMD18 success!");
goto read_data1;
}
}

usart_puts("CMD18 error"); return 0;

read_data1:

and the function CMD18() goes like..
void CMD18(void)
{
SPI(0x52);
SPI(0x00);
SPI(0x00);
SPI(0x05);
SPI(0x12);
SPI(0x0FF);
}
--
Regards

Chuck, you are the man :)

I very much recommend your tutorial on using SD card. Real time-saver. Thumbs up!

Hello Chuck Baird,

Thanks a LOT !! for the posting the tutorial - SD and Butterfly.doc

Its a very handy - easy to implement Document.

after refering your documnet I was able to sucessfully Initilze the 256 MB SD Card.

But, I had issues in initilizing the 1 GB SD card
Is there any timing Issue ?

Thanks once again.

-Mandar Bagul
India

Hello Chuck Baird,

Today, I have tried out interfacing the 1 GB SD Card from Transcend & it work fine !!

Conclusion : The tutorial - SD and Butterfly.doc is valid for 1 GB SD Card from Transcend.

Thanks a Lot once again !!

-Mandar Bagul.

update: double post

hah, i need to be logged to see that little grid ;)