E²PROM Serial Memory

[EN0]

Hello,

I'm trying to write to this serial E²PROM device, the 24AA08, and I can't get it working! Here's my code:

/************************************************************************
*
* Module:       Serial_E²PROM_1.C
* Description:  Code to test serial E²PROM functionality.
* Line length:  120 characters [only if the length is longer than 80 chars]
* Functions:    Void
*
* Date:	      Author:		Comments:
* 12 Jun 2011   Austin Schaller    	Created
*
************************************************************************/


#include <p18f4220.h>
#include <delays.h>
#include <i2c.h>
#pragma config OSC=INTIO2, WDT=OFF, LVP=OFF, DEBUG=ON

//** Defines ***********************************************************
#define		CONTROL		0xA0		// Control nibble + (B1 = 0) + (B2 = 0)
#define		ADDRESS		0x00		// Start from the beginning
#define		DATA		0xFF		// Arbitrary

#define		DEL05S		Delay10KTCYx(100)		//Delay 0.5 seconds
#define		DEL1S		Delay10KTCYx(200)		// Delay 1 econd


void main(void)
{
	// Variable Declarations
	int i, ack;
	
	// Oscillator settings
	OSCCON = 0x70;		// OSC = 8 MHz
	while(!OSCCONbits.IOFS);		// Wait for OSC to be ready
	
	TRISAbits.TRISA0 = 0;		// RA0 as  output
	TRISC = 0x0C;		// RC3 = SCL, RC4 = SDA
	
	OpenI2C(MASTER, SLEW_OFF);
	SSPADD = 4;		/* 400 kHz baud @ 8 MHz
					Clock = ((Fosc/CLK)/4) - 1*/
	
	// Write to serial E²PROM
	EEByteWrite(CONTROL, ADDRESS, DATA);
	ack = EEAckPolling(CONTROL);

	if(!ack)
	{
		// Blink status LED five times
		for(i = 0; i < 5; i++)
		{
			LATAbits.LATA0 = ~LATAbits.LATA0;		// Invert sign of RA0
			DEL05S;		// Delay half a second
		}
	}
	else
	{
		// Show nothing, NOTHING!
		LATAbits.LATA0 = 0;
	}
}

I can see data pulses on my SDA line, but not SCL. I've spent a lot of time on this and just can't figure what's going on!

Hopefully one of you can!

Thanks,

Austin

 

[Ian Rogers]

Code should work.. Have you addressed the 24aa08 a0,a1,a2 and wp to ground? I personally don't use Microchips routine as I had problems so I wrote my own.

 

[EN0]

I didn't know that A0, A1, and A2 needed to be pulled to ground! That's probably my issue.

Eventually I would like to write my own serial libraries, but due to time constraints at the moment, I'm just going to use Microchip's routine.

 

[EN0]

I reconfigured the hardware, tried doing it again, but my attempt was futile!

What's going on?

 

[EN0]

I did a little debugging and stepped through the code I have in addition to the EEByteWrite() and EEAckPolling(). It stopped at this point:

  if ( PIR2bits.BCLIF )           // test for bus collision
  {
    return ( -1 );                // return with Bus Collision error 
  }

I went ahead and double-checked the PIR2 register and confirmed that it read 0x08, thus giving me a bus collision error.

Evidently, something was actively inconsistent on the I²C bus, so upon further inspection, I found that one of my pullup resistors was connected to Vss!

So I fixed that hardware issue and now it is successful!

I need to pay more close attention, but thanks for your help guys!