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ARM7 LPC2148 Development board

The ARM7 LPC2148 Development board is specifically designed to help students to master the required skills in the area of embedded systems. The kit is designed in such way that all the possible features of the microcontroller will be easily used by the students. The kit supports in system programming (ISP) which is done through serial port.

NXP’s ARM7 (LPC2148), ARM Development Kit is proposed to smooth the progress of developing and debugging of various designs encompassing of High speed 32-bit Microcontrollers.

I2C (Inter Integrated Circuit)

The I2C (Inter-IC) bus is a bi-directional two-wire serial bus that provides a communication link between integrated circuits (ICs).I2C is a synchronous protocol that allows a master device to initiate communication with a slave device. Data is exchanged between these devices.

EEPROM

EEPROM (electrically erasable programmable read-only memory) is user-modifiable read-only memory (ROM) that can be erased and reprogrammed (written to) repeatedly through the application of higher than normal electrical voltage. It is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration tables or device configuration.

Interfacing I2C - EEPROM

Fig. 1 shows how to interface the EEPROM with microcontroller through I2C. I2C is a Master-Slave protocol. I2C has a clock pulse along with the data. Normally, the master device controls the clock line, SCL. This line dictates the timing of all transfers on the I2C bus. No data will be transferred unless the clock is manipulated. All slaves are controlled by the same clock, SCL.

I2c bus supports many devices, each device is recognized by a unique address—whether it’s a micro-controller, LCD Driver, memory or keyboard interface and can operate as transmitter or receiver based on the functioning of the device. The controller designed controls the EEPROM device through I2C protocol. The I2C Controller here acts as a master device and controls EEPROM which acts as a slave. The read-write operations are accomplished by sending a set of control signals including the address and/or data bits. The control signals must be accompanied with proper clock signals.





Fig. 1 Interfacing I2C - EEPROM to Microcontroller

Interfacing I2C – EEPROM with LPC2148

Read, write and Erase EEPROM by using I2C in LPC2148 Development Board.. Wiring up an I2C based EEPROM to the I2C port is relatively simple. The basic operation of the I2C based EEPROM's is to send a command, such as WRITE, followed by an address and the data. In WRITE operation, the EEPROM to store the data.

In LPC2148 Development Kit 2 nos. of EEPROM lines are controlled by I2C Enabled drivers. I2C Lines serial clock SCL (P0.2), serial data SDA (P0.3) connected to the I2C based serial EEPROM IC. The EEPROM read & write operations are done in LPC2148 Development Kit by using these SDA & SCL I2C lines.

Pin Assignment with LPC2148

 

 

I2C EEPROM

LPC2148 Lines

Serial EEPROM

AT 24xx

SCL

SCL1 -  (P0.11)

            

SDA

SDA1 -  (P0.14) 

 



Circuit Diagram to Interface I2C–EEPROM with LPC2148





Source Code

The Interfacing I2C – EEPROM with LPC2148 program is very simple and straight forward that read, write and erase operations in EEPROM by using I2C & the value is displayed in serial port. A delay is occurring in every single data read or write in EEPROM. The delay depends on compiler how it optimizes the loops as soon as you make changes in the options the delay changes.

C Program to interface I2C – EEPROM using LPC2148

***************************************************************************************

Title : Program to read, write & erase of I2C - EEPROM

***************************************************************************************

#include 
#include 
#include 
#include "UART.h"

//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
/************************************    Macros     *******************************************/
#define SW3		1<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
/*<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<   Declarations  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>*/
//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
void I2C_ISR(void)__irq;

void Wait (unsigned int);
void I2C_Init (void);

int I2C_Start (unsigned int Slave_Addr);
int I2C_Write (unsigned char *Buff, unsigned int Count);


char ReLoad[MAX]	=	{0x00/*Address Low Bits*/,0x00/*Address Low Bits*/,'A','R','M','7','P','R','I', 'M', 'E', 'R'};
char Buff[MAX]		=	{0x00/*Address Low Bits*/,0x00/*Address Low Bits*/,'A','R','M','7','P','R','I', 'M', 'E', 'R'};

unsigned char Rec[MAX]	=	{"NO-DATA!"};
unsigned char index		=	0;
unsigned char flag = 0, ii, Ready=0, Erase = 0;

//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

void Delay(void)
{
	unsigned int i,j;
	
	for(i=0;i<150;i++)
		for(j=0;j<900;j++);
}

void Wait (unsigned int Delay)
{
	while(Delay--);
}

void I2C_Init (void)
{
	I2C1SCLH	=	150;			//50%duty cycle .....   I2C Frequency ->100 KHz for PCLK = 30MHz 
	I2C1SCLL	=	150;
	I2C1CONSET	=	1 << I2EN;	//Enable I2C 1

}

int I2C_Start (unsigned int Slave_Addr)
{
	I2C1CONCLR	=	1 << STO;
	I2C1CONSET	=	1 << AA;

	I2C1CONSET	=	1 << STA;

	return 0;
}

int I2C_Write (unsigned char *Buff, unsigned int Count)
{
	while(Count--)
	{
		I2C1DAT		=	*Buff++;
	}
	return 0;
}
//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<   Main Function  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


int main()
{
	unsigned int i;
	VPBDIV	=	0x02;
	PINSEL0	=	0x30C00005;						// P0.11 - SCLK1 and P0.14	- SDA1 
	PINSEL2	&=	0xFFFFFFF3;

	IO1DIR	=	0x00 << SW3;
	IO1DIR	|=	0xFF << 16;

	UART0_Init (9600);

	VICIntSelect	= 0<<19;
	VICVectCntl0 	= 0x020 | 19 ;
	VICVectAddr0 	= (unsigned long)I2C_ISR;
	VICIntEnable 	= 1<<19;

	
	/*	
		Before the master transmitter mode
		can be entered, the I2CONSET register must be initialized
	*/


	I2C_Init();
   
	UART0_PutS ("********* ARM Primer LPC-2148 I2C EEPROM Demo **********\n\n\r");
	UART0_PutS (">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n\n\r");
	UART0_PutS ("[~] Turn SW 20 ON to Write default data to EEPROM! \n\r");
	UART0_PutS ("[~] Turn SW 21 ON to Read and Display data from EEPROM! \n\r");
	UART0_PutS ("[~] Turn SW 22 ON to Erase data from EEPROM \n\r");
	
	IO1CLR	=	0xFF << 16;
	while (1)
	{
		if ((IOPIN1 & SW3) == 0)					/*...To Load the Default Data to the EEPROM ...*/
		{
			ii = 0;
			IOCLR1	=	0xFF << 16;
			IOSET1	=	1 << 16;
			while (ii < MAX)  						//Re-load Default Data to Buff
			{
				Buff [ii]	=	ReLoad [ii];
				ii++;
			}

			Wait (5000);			
			flag	=	'W';
			I2C_Start (0x70);
	
			for (i=0;i<30;i++)	Wait(10000);
	
			I2C1CONCLR	=	1 << SI;
			while (!(IOPIN1 & SW3));
			Wait (5000);Wait (5000);
		}
			
		else if ((IOPIN1 & SW4) == 0)				/*..To Read the Data Stored in the EEPROM...*/
		{
			IOCLR1	=	0xFF << 16;
			IOSET1	=	1 << 17;
			
			flag 	=	'R';
			I2C_Start (0x70);
	
			for (i=0;i<30;i++)	Wait(10000);
	
			I2C1CONCLR	=	1 << SI;

			while (Ready == 'F');							//Ready = FALSE

			if (Ready == 'T')						//Check if Ready = TRUE
			{
				ii=0;
				UART0_PutS ("\n\r The Read Data are: \t");
				while (ii<MAX)
				{
					//U0THR	=	'\n';
					Wait (1000);
					U0THR	=	Rec[ii];
					Wait (1000);
					ii++;
				}
				UART0_PutC ('\n');
				Wait (1000);
				Ready 	=	'F';
			}
			while (!(IOPIN1 & SW4));
			Wait (5000);Wait (5000);Wait (5000);Wait (5000);
			
		}

		if ((IOPIN1 & SW5) == 0) 						/*To Erase the Content in EEPROM*/
		{
			IOCLR1	=	0xFF << 16;
			IOSET1	=	1 << 18;
			ii = 2;
			Erase	=	1;
			while (ii < MAX)
			{
				Buff[ii]	=	0xFF; 					//Load 0xFF to EEPROM
				ii++;
			}
			flag	=	'W';
			I2C_Start (0x70);
	
			for (i=0;i<30;i++)	Wait(10000);
	
			I2C1CONCLR	=	1 << SI;	

			while (!(IOPIN1 & SW5));
			Wait (5000);Wait (5000);Wait (5000);Wait (5000);
		}
	}		 

}

void I2C_ISR(void) __irq
{
	if (I2C1CONSET & 0x08)
	{
		

		switch (I2C1STAT)
		{
			case (0x08)	:/*... A START condition has been Transmitted...*/	

							if (flag == 'W')
							{
								I2C1CONCLR	=	1 << STO;
								I2C1CONCLR	=	1 << STA;	//Clear START Bit
								I2C1DAT		=	0xA0;		//Slave Addr + W  1010 p2 p1 p0 w
								I2C1CONCLR	=	1 << SI;
								
							}
							else if (flag == 'R')
							{
								I2C1DAT		=	0xA0;		//Slave Addr + R  1010 p2 p1 p0 r	
								I2C_Start (0xA1);
								I2C1CONCLR	=	1 << SI;
								
							}
							index	=	0;
							break;
	
			case (0x10)	:	/*...A repeated START condition has been Transmitted...*/

							I2C1CONCLR	=	1 << STA;	
							if (flag == 'W')
								I2C1DAT	=	0xA0;		//Slave Addr + W  1010 p2 p1 p0 w
							else if (flag == 'R')
							{
								I2C1CONCLR	=	1 << STA;
								I2C1CONCLR	=	1 << STO;	
								I2C1DAT		=	0xA1;		//Slave Addr + R  1010 p2 p1 p0 r	
								I2C1CONCLR	=	1 << SI;
								index = 0;
							}
							
							break;
	
			case (0x18)	:	/*....SLA+W has been transmitted; ACK has been received....*/

							I2C1CONCLR	=	0x20;		//Clear START Bit
							I2C1CONCLR	=	0x38;		//Clear all flags (STA, STO, SI)
							I2C1DAT		=	Buff[index];
							index++;
							
							break;
	
			case (0x20)	:	/*...SLA+W has been transmitted; NOT ACK has been received....*/

							I2C1CONCLR	=	0x20;		//Clear START Bit
							I2C1CONCLR	=	0x38;		//Clear all flags (STA, STO, SI)
							I2C1DAT		=	Buff[index];
							index++;						
							break;
	
			case (0x28)	:	/*...Data byte in I2DAT has been transmitted; ACK has been received....*/

							if (index < MAX)   				// Place all the contents of Buff[] in I2C1DAT
							{
								if (flag == 'W')
								{
									I2C1DAT		=	Buff[index];
									I2C1CONCLR	=	0x20;		//Clear START Bit
									I2C1CONCLR	=	0x38;		//Clear all flags (STA, STO, SI)
								
								}
								else if ((index > 1) && flag == 'R')	//Generate a Repeated Start to jump to MST/REC Mode
								{
									I2C1CONCLR	=	0x18;
									I2C1CONSET	=	1 << STA;
									
								}
								else							// Send Upper Nibble of Adress to Read the Data... 
								{
									I2C1DAT		=	Buff[index];
									I2C1CONCLR	=	0x20;		//Clear START Bit
									I2C1CONCLR	=	0x38;		//Clear all flags (STA, STO, SI)
									
								}
										
								index++;
							}
							else								//Stop Transmission to EEPROM.... Data Count Reset..
							{
								index = 0;
								flag = 'R';
								I2C1CONSET	=	1 << STO;		//Send STOP Bit
								if (Erase == 1)
								{
									UART0_PutS ("\n\r Memory Erase Successfull..! \n");
									Erase	=	0;
								}
								else
								{
									UART0_PutS ("\n\r Data Successfully Written on Memory!\n");
								}
								I2C1CONCLR	=	1 << STA;
								I2C1CONCLR	=	1 << SI;
							}
							break;
	
			case (0x30)	:	/*... Data byte in I2DAT has been transmitted; NOT ACK has been received ...*/

							I2C1CONCLR	=	0x20;		//Clear START Bit
							if (index < MAX)
							{
								if (flag == 'W')
								{
									I2C1DAT		=	Buff[index];
								
								}
															
								index++;
							}
							else
							{
								index = 0;
								flag = 0;
								I2C1CONSET	=	0x10;		//Send STOP Bit
								I2C1CONCLR	=	1 << SI;
								
							}
							break;
	
			case (0x38)	:	/*... Arbitration lost in SLA+R/W or Data bytes ....*/

							I2C1CONSET	=	0x20;
							break;

			case (0x40)	:	/*... SLA+R has been transmitted; ACK has been received.*/

							I2C1CONSET	=	1 << AA;
							I2C1CONCLR	=	1 << STA;
							I2C1CONCLR	=	1 << STO;
							I2C1CONCLR	=	1 << SI;
							break;

			case (0x48)	:	/*...SLA+R has been transmitted; NOT ACK has been received ...*/

							I2C1CONSET	=	1 << STA;		//Repeated Start
							break;

			case (0x50)	:	/*... Data byte has been received; ACK has been returned ....*/

							I2C1CONSET	=	1 << AA;	
							if (index < MAX)
							{
								Rec [index]	=	I2C1DAT;
								index++;
							
							}
							else
							{
								I2C1CONSET	=	1 << STO;
								I2C1CONCLR	=	1 << SI;
								index = 0;
								Ready	=	'T';			//Make Ready TRUE after Reading is over!
							}
							break;

			case (0x58)	:	/*... Data byte has been received; NOT ACK has been returned ....*/
			
							Rec [index]	=	I2C1DAT;
							I2C1CONCLR	=	1 << STA;
							I2C1CONCLR	=	1 << STO;
							break;
							
		}
	}
	I2C1CONCLR	=	1 << SI;
	VICVectAddr	=	0x00;
}

To compile the above C code you need the KEIL software. They must be properly set up and a project with correct settings must be created in order to compile the code. To compile the above code, the C file must be added to the project.

In Keil, you want to develop or debug the project without any hardware setup. You must compile the code for generating HEX file. In debugging Mode, you want to check the port output without LPC2148 Development Board..

The Flash Magic software is used to download the hex file into your microcontroller IC LPC2148 through UART0.

Testing the I2C – EEPROM with LPC2148

Give +3.3V power supply to LPC2148 Development Board.; the EEPROM device is connected with the LPC2148 Development Board.. First check the entire EEPROM device fixed properly. A serial cable is connected between the microcontroller and PC.

In PC, open the Hyper Terminal for displaying the values from EEPROM through I2C.

  • If you want to write any data into EEPROM then you just pressed the switch, sw20. Now, you can write any values into the EEPROM perma