I2C Interface between 2 Tiva C Launchpad

Hello Phan,

Do you have the Pull Up resistance on the SCL and SDA? Can you also refer to the following application note.

www.ti.com/.../spma073.pdf

One thing I did notice in the master code is the following

while(!(I2CSlaveStatus(I2C0_BASE) & I2C_SLAVE_ACT_RREQ));

That is incorrect. A master cannot know about the remote slave. You should instead be using I2CMatserBusy to poll.

Also it will be worth the effort to capture a scope snapshot to see what is happening on the bus.

Regards
Amit

Hello,

If you just want a channel of communication I advise a SPI interface to be used instead of i2c. It's just so much more simple. (This saying from someone that doesn't like i2c :p)

Unless you of course really need multiple slaves with just 2 I/O and/or are trying to learn for a future implementation

Luis Afonso said:

If you just want a channel of communication I advise a SPI interface to be used instead of i2c.

Yes - poster (could) do that - but isn't an obvious - and far easier "channel of communication" available?

Poster has mastered UART - thus ALL "new learning" and struggling is eliminated by having 2 TM4C's "talk together" via UART!  

• Multiple UARTs appear on most all ARM implementations, thus "squeezing out" a 2nd UART channel should not be difficult.
• Poster specified MCU to MCU - so the "fringe benefit" of I2C (or SPI) is null.  
• And - if greater distance is (or becomes) helpful and/or required - UART into RS232 well accommodates!    Both I2C and SPI "cash out" should greater distance be helpful and/or demanded...

Ease, existing familiarity, design speed and far greater range - all point to UART as "best" for this poster...  

Thank you so much, my project performed! :)

Hello Phan

What was the issue?

Regards
Amit

I could transmit data from Master to Slave. Now, I 'm trying to read data from Slave, but all i receive is 'y' symbol! I think command 

I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_RECEIVE); influence my code, or may be interrupt. Please help me, Thank you so much!

This is Master code:

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_ints.h"
#include "inc/hw_i2c.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "inc/hw_gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/i2c.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/uart.h"
#include "utils/uartstdio.h"
#include "utils/uartstdio.c"

#define SLAVE_ADDRESS 0x3C
volatile uint32_t 	read;
volatile uint32_t receive;

void I2C0MasterIntHandler(void)
{
	// Clear the I2C0 interrupt flag.
	I2CMasterIntClear(I2C0_BASE);
	// Read the data from the slave.
	receive = I2CMasterDataGet(I2C0_BASE);
}

void InitConsole(void)
{
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);

	GPIOPinConfigure(GPIO_PA0_U0RX);
	GPIOPinConfigure(GPIO_PA1_U0TX);

	SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
	UARTClockSourceSet(UART0_BASE, UART_CLOCK_PIOSC);
	GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
	UARTStdioConfig(0, 115200, 16000000);
}

void I2C0_Master_Init(void)
{
	//enable GPIO peripheral that contains I2C 0
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
	while(!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOB));

	//enable I2C module 0
	SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);
	//reset module
	SysCtlPeripheralReset(SYSCTL_PERIPH_I2C0);

	// Configure the pin muxing for I2C0 functions on port B2 and B3.
	GPIOPinConfigure(GPIO_PB2_I2C0SCL);
	GPIOPinConfigure(GPIO_PB3_I2C0SDA);

	// Select the I2C function for these pins.
	GPIOPinTypeI2CSCL(GPIO_PORTB_BASE, GPIO_PIN_2);
	GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_3);

	// Enable and initialize the I2C0 master module.  Use the system clock for
	// the I2C0 module.  The last parameter sets the I2C data transfer rate.
	// If false the data rate is set to 100kbps and if true the data rate will
	// be set to 400kbps.
	I2CMasterInitExpClk(I2C0_BASE, SysCtlClockGet(), false);

	//clear I2C FIFOs
	// HWREG(I2C0_BASE + I2C_O_FIFOCTL) = 80008000;

}

int main(void)
{
	SysCtlClockSet(SYSCTL_SYSDIV_1| SYSCTL_USE_OSC| SYSCTL_OSC_MAIN| SYSCTL_XTAL_16MHZ);

	InitConsole();
	I2C0_Master_Init();

	IntEnable(INT_I2C0);
	I2CMasterIntEnableEx(I2C0_BASE, I2C_MASTER_INT_DATA);
	IntMasterEnable();

	UARTprintf("Master --> Slave \n");

	while(1)
	{
		I2CMasterSlaveAddrSet(I2C0_BASE, SLAVE_ADDRESS, true);
		I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_RECEIVE);
		while(I2CMasterBusy(I2C0_BASE));

		UARTprintf("Received: %d \n", receive);
		UARTprintf("received: '%c' \n", receive);

		SysCtlDelay(SysCtlClockGet()/6);
	}
}

And Slave:

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_ints.h"
#include "inc/hw_i2c.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "inc/hw_gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/i2c.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/uart.h"
#include "utils/uartstdio.h"
#include "utils/uartstdio.c"

#define SLAVE_ADDRESS 0x3C
volatile uint32_t   result = 'V';

void InitConsole(void)
{
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);

	GPIOPinConfigure(GPIO_PA0_U0RX);
	GPIOPinConfigure(GPIO_PA1_U0TX);

	SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
	UARTClockSourceSet(UART0_BASE, UART_CLOCK_PIOSC);
	GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
	UARTStdioConfig(0, 115200, 16000000);
}


void I2C1_Slave_Init(void)
{
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
	while(!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOA));

	SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C1);
	SysCtlPeripheralReset(SYSCTL_PERIPH_I2C1);

	GPIOPinConfigure(GPIO_PA6_I2C1SCL);
	GPIOPinConfigure(GPIO_PA7_I2C1SDA);

	GPIOPinTypeI2CSCL(GPIO_PORTA_BASE, GPIO_PIN_6);
	GPIOPinTypeI2C(GPIO_PORTA_BASE, GPIO_PIN_7);

	I2CSlaveEnable(I2C1_BASE);
	I2CSlaveInit(I2C1_BASE, SLAVE_ADDRESS);
}

void I2C1SlaveIntHandler(void)
{
	// Clear the I2C0 interrupt flag.
	I2CSlaveIntClear(I2C1_BASE);
	// Read the data from the slave.
	result = I2CSlaveDataGet(I2C1_BASE);
}

int main(void)
{
	SysCtlClockSet(SYSCTL_SYSDIV_1| SYSCTL_USE_OSC| SYSCTL_OSC_MAIN| SYSCTL_XTAL_16MHZ);

	InitConsole();
	I2C1_Slave_Init();

	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
	GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);
	GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, 0);

	IntEnable(INT_I2C1);
	I2CSlaveIntEnableEx(I2C1_BASE, I2C_SLAVE_INT_DATA);
	IntMasterEnable();

	while(1)
	{
		//I2CSlaveDataPut(I2C1_BASE, result);
		UARTprintf(" Slave receive: '%c' \n", result);
		SysCtlDelay(SysCtlClockGet()/12);

		//while(!(I2CSlaveStatus(I2C1_BASE) & I2C_SLAVE_ACT_TREQ));

		I2CSlaveDataPut(I2C1_BASE, result);
	}
}

Like you said: while(!(I2CSlaveStatus(I2C0_BASE) & I2C_SLAVE_ACT_RREQ)); is incorrect, and one more, i didn't use pull up resistor!

Hello Phan Vu

Thank you for the confirmation. Indeed Pull Up is required and that is why the Application Note concentrates on why.

Regards
Amit