Has anyone managed to get a DS1305 working with SPI

[JamesW]

if so, can anyone give me few pointers please?

I am running on a 18F4525 at 20MHz, the chip select is on pin A5, the sermode pin on the DS1305 is at VCC.

(I know the SPI is working, as I have a MAX3110 on it that I have already got working).

Looking at the output data from the chip on a logic analyser it is doing absolutely nothing. (The write and read looks fine with the right number of clock signals etc.)

Theoretically If I write data to the 1st address in ram, and read from it using the routines below, I should be able to get something, but I get nothing. (The line just sits there at 5v)

I have got a 100K pull up on the SDO from the DS1305 as well, as I saw a post elsewhere that said it was an open collector output.

I have tried just these combinations of setup_spi just in case

setup_spi(SPI_MASTER | SPI_XMIT_L_TO_H | SPI_CLK_DIV_64);
setup_spi(SPI_MASTER | SPI_L_TO_H | SPI_CLK_DIV_64);
setup_spi(SPI_MASTER | SPI_H_TO_L | SPI_CLK_DIV_64);

I must be missing a fundemental point, but cannot work out what.

Any pointers would be very gratefully received, as I am tearing my hair out at the moment

Code is below

Cheers James


/* ------------------------------------------------------------------------- */
/* ROUTINE TO WRITE A BYTE TO THE DS1305 */

void write_ds1305_byte(BYTE cmd)
{
BYTE i;

spi_write(cmd);

}
/* ------------------------------------------------------------------------- */
/* ROUTINE TO WRITE A BYTE TO AN ADDRESS IN THE DS1305 */
void write_ds1305(BYTE cmd, BYTE data)
{
unsigned int temp;
output_high(DS1305_CS);
delay_us(10);

write_ds1305_byte(cmd);
write_ds1305_byte(data);

delay_us(10);

output_low(DS1305_CS);
}
/* ------------------------------------------------------------------------- */
/* ROUTINE TO READ A BYTE FROM A DS1305 */

BYTE read_ds1305(BYTE cmd)
{
BYTE i,data;

output_high(DS1305_CS);

delay_us(100);

spi_write(cmd);
delay_us(5);
data = spi_read(0);

delay_us(10);

output_low(DS1305_CS);


return(data);
}

/* ------------------------------------------------------------------------- */
void rtc_write_nvr(BYTE address, BYTE data)
{ //valid address: 0x00 to 0x5F
write_ds1305(address | 0xa0, data);
}
/* ------------------------------------------------------------------------- */
BYTE rtc_read_nvr(BYTE address)
{
return(read_ds1305(address | 0x20));
}

[PCM programmer]

With respect to the hardware:

1. Do you have Vccif connected to Vcc1 (both at +5v) ?

2. Do you have a 3v lithium battery connected to Vbat ?

3. Do you have a 32.768 KHz crystal connected to X1 and X2 ?

4. Do you have Vcc2 connected to Ground ?


Also, I don't see an init routine in your code, that sets up the
control register to remove Write Protect and to enable the oscillator.

[JamesW]

ahh - thanks for that, I didn't notice the read/write flag in the datasheet.

I had it working, but now it's stopped again! Damn hardware!

Cheers

James