Update.

I inserted a delay after the first function call like this:

// Write Slave address and set master for transmission
I2CResult=MasterWriteI2C1((I2CDevAddress << 1) & 0xfe);
asm("nop");


for (temp=0; temp<1000; temp++)
{
}

Now I am getting the 9th (ACK) clock.

Inserting these delays throughout allowed me to get all the write 
function calls to complete.

Maybe it's some kind of interaction with the Picket 3 and MPlab.

Or maybe I'm checking the wrong flag?

Mark

Mark E. Skeels wrote:
> Hi, List,
>
> I am working with the PIC24HJ64GP210, C30 and the 16 bit Peripheral 
> library I2C functions.
>
> I am trying to write/read a Maxim DS1337 RTC chip.
>
> I started with some sample code for interfacing I2C EEPROMs and now have 
> the code below.
>
> I have read the data sheet and user's guide but I don't yet fully 
> understand how to configure all of the control bits, so I gave it my 
> best shot.
>
> /_*My problem:*_/ At line /_*1*_/ below, the I2C peripheral clocks only 
> 8 times after start condition, so I never see the ACK from the slave DS1337.
>
> Both of the following checks for TBF and ACK fall through and at line 
> */_2_/* the function MasterWriteI2C1 returns a -1, indicating a bus 
> collision.
>
> /_*My Question:*_/ How do I get the I2C peripheral to clock out the 9th 
> time so I can get the ACK bit from the DS1337?
>
> Many thanks,
> Mark
>
> /***************************************************************
> * Write a block of chars into the Maxim DS1337 RTC I2C device.
> *
> * I2CAddress contains internal starting memory location of RTC
> * p_I2CWriteBlock points to first location of a block of chars
> * BlockLen contains number of characters in the data block
> * I2CDevAddress contains I2C device address
> ***************************************************************/
> void I2CWriteBlock(unsigned char I2CAddress, unsigned char 
> *p_I2CWriteBlock, unsigned int BlockLength, unsigned char I2CDevAddress)
> {
> unsigned char i, I2CResult;
> unsigned int config1;
>
> //**** begin test code to fill the array with know data
> unsigned char *p_TempBlock;
> p_TempBlock=p_I2CWriteBlock;
>
> for (i=0; i<BlockLength; i++)
> {
> *p_TempBlock = 0xad;
> p_TempBlock++;
> }
> //*** end test code.
>
> /* Configure I2C for 7 bit address mode 400 KHz operation.....??*/
> config1 = (
> I2C1_ON & I2C1_IDLE_CON & /*I2C1_CLK_HLD &*/
> I2C1_IPMI_DIS & I2C1_7BIT_ADD &
> I2C1_SLW_EN & I2C1_SM_DIS &
> I2C1_GCALL_DIS & I2C1_STR_DIS &
> I2C1_NACK & I2C1_ACK_EN & I2C1_RCV_DIS &
> I2C1_STOP_DIS & I2C1_RESTART_DIS &
> I2C1_START_DIS
> );
>
> //Enable I2C module 1 for use.
> OpenI2C1( config1 , BRG_VAL ); //BRG_VAL is a constant;currently gives 
> ~330 KHz bus speed
> asm("nop"); //asm's help with breakpoint debugging using Pickit 3
>
> //Wait for bus to become available
> IdleI2C1();
> asm("nop");
>
> // Set a start condition on the bus
> StartI2C1();
> asm("nop");
>
> //wait for start sequence to finish...
> while(I2C1CONbits.SEN );
> asm("nop");
>
> // Write Slave address and set master for transmission
> /_*1*_/ I2CResult=MasterWriteI2C1((I2CDevAddress << 1) & 0xfe);
> asm("nop");
>
> // Wait till I2C device address is transmitted
> while(I2C1STATbits.TBF);
> asm("nop");
>
> //wait for the ACK...(it should be low so wait while high)
> while(I2C1STATbits.ACKSTAT);
> asm("nop");
>
> // Set the starting location in the I2C device to be written
> /_*2*_/ I2CResult=MasterWriteI2C1(I2CAddress);
> asm("nop");
>
> //Wait till I2C device address is transmitted
> while(I2C1STATbits.TBF);
> asm("nop");
>
> //wait for the ACK...(it should be low so wait while high)
> while(I2C1STATbits.ACKSTAT);
> asm("nop");
>
> //write the data
> for (i=0; i<(BlockLength); i++)
> {
> asm("nop");
> //Write a byte
> I2CResult=MasterWriteI2C1(*p_I2CWriteBlock);
> asm("nop");
>
> /* Wait till I2C device address is transmitted */
> while(I2C1STATbits.TBF);
> //wait for the ACK...(it should be low so wait while high)
> asm("nop");
>
> //wait for ACK
> while(I2C1STATbits.ACKSTAT);
> asm("nop");
>
> //next byte
> p_I2CWriteBlock++;
> }
> asm("nop");
>
> // Set a stop condition on the bus
> StopI2C1();
> asm("nop");
>
> //Close I2C module 1
> CloseI2C1();
> asm("nop");
> }
>
>   
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