Compiler/TM4C123GH6PZ: Communication between two TIVA board using I2C

Hi sir,

I was on leave for last one week ,so I am unable to reply. Sorry for the late reply.

1. Did you install external pull-up resistors on one of the two LaunchPad's? I2C needs the pull-ups to work.

Yes sir, I am using external pull-up resistors.

2. Also I don't see any UART code for the slave, so can you share that code so I can test it with the UART outputs?

No sir, I didn't add any UART code in my slave.Because I am connecting UART to my master device.

What I am trying to do is sending the data from master to slave and slave send back the same data to the master and UART is connected to master, so through UART it should display whatever the data, I am sending back to master from the slave. So for this condition I was not connecting UART to slave.

I tried master to slave communication separately and it is working fine, whatever the data I am sending from master, is receiving correctly in slave and display through UART. The issue I am facing is sending the same data back to the master from slave.

Thank you,

Alphy

Hi sir,

I am waiting for your reply.Please help me to solve the issue.

I was tried to send data from slave to master and that is also working fine.I am facing issues while sending data from master to slave and send the same data back to slave.Please help me to solve the issue as soon as possible.

Thank you,

Alphy

Hi Sir,

Thank you so much for your quickest reply.

Yeah sir, modification in working code is easy.

The working code is given below.

Master code

#define SLAVE_ADDRESS 0x20
int main()
{

uint32_t n=3,i;
char char_tx[]="abcd";

SysCtlClockSet(SYSCTL_SYSDIV_1|SYSCTL_USE_OSC |SYSCTL_XTAL_8MHZ|SYSCTL_OSC_MAIN); //seting system clock as 8Mhz

SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);
while(!SysCtlPeripheralReady(SYSCTL_PERIPH_I2C0));
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
while(!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOB));
//configure the muxing and GPIO settings to bring the SSI functions out to the pins
GPIOPinTypeI2CSCL(GPIO_PORTB_BASE, GPIO_PIN_2);
GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_3);
GPIOPinConfigure(GPIO_PB2_I2C0SCL);
GPIOPinConfigure(GPIO_PB3_I2C0SDA);
I2CMasterEnable(I2C0_BASE);

I2CMasterInitExpClk(I2C0_BASE,SysCtlClockGet(),false);

while(1)
{

I2CMasterSlaveAddrSet(I2C0_BASE,SLAVE_ADDRESS,false);

if(char_tx[1] == '\0')
{
//Initiate send of data from the MCU
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_SEND);

// Wait until MCU is done transferring.
while(I2CMasterBusy(I2C0_BASE));
}

else{

I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);

// Wait until MCU is done transferring.
while(I2CMasterBusy(I2C0_BASE));

for(i=1;i<n;i++)
{
//put next piece of data into I2C FIFO
I2CMasterDataPut(I2C0_BASE, char_tx[i]);

//send next data that was just placed into FIFO
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_CONT);
//
// // Wait until MCU is done transferring.
while(I2CMasterBusy(I2C0_BASE));
// i++;
}

I2CMasterDataPut(I2C0_BASE, char_tx[n]);

//send next data that was just placed into FIFO
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_FINISH);
while(I2CMasterBusy(I2C0_BASE));

}}}

Slave code

int main()
{
char data, char_rx[5],receive;
// uint32_t pui32DataTx;
uint32_t n=5,i;
//uint32_t pui32DataRx[5];
//uint32_t ui32Period;
SysCtlClockSet(SYSCTL_SYSDIV_1|SYSCTL_USE_OSC|SYSCTL_XTAL_8MHZ|SYSCTL_OSC_MAIN); //seting system clock as 8Mhz
InitConsole();

SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);
while(!SysCtlPeripheralReady(SYSCTL_PERIPH_I2C0));
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
while(!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOB));
//configure the muxing and GPIO settings to bring the SSI functions out to the pins
GPIOPinTypeI2CSCL(GPIO_PORTB_BASE, GPIO_PIN_2);
GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_3);
GPIOPinConfigure(GPIO_PB2_I2C0SCL);
GPIOPinConfigure(GPIO_PB3_I2C0SDA);
I2CSlaveAddressSet(I2C0_BASE,0,0x20);
I2CSlaveInit(I2C0_BASE,0x20);
I2CSlaveEnable(I2C0_BASE);

while(1) {
//
// Place the data to be sent in the data register
//
for(i=0;i<=n;i++){
//pui32DataRx[i]=I2CSlaveDataGet(I2C0_BASE);
char_rx[i]=I2CSlaveDataGet(I2C0_BASE);
// Wait until the slave has received and acknowledged the data.
while(!(I2CSlaveStatus(I2C0_BASE) & I2C_SLAVE_ACT_RREQ));
UARTCharPut(UART0_BASE,char_rx[i]);
}}}

//

//UART Function for displaying the data sent from master

//

void InitConsole(void)
{
//
// Enable the UART0 module.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
//
// Wait for the UART0 module to be ready.
//
while(!SysCtlPeripheralReady(SYSCTL_PERIPH_UART0));
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
while(!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOA));
GPIOPinConfigure(GPIO_PA0_U0RX);
GPIOPinConfigure(GPIO_PA1_U0TX);
GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
UARTConfigSetExpClk(UART0_BASE, SysCtlClockGet(), 115200,(UART_CONFIG_WLEN_8|UART_CONFIG_STOP_ONE|UART_CONFIG_PAR_NONE));
UARTCharPut(UART0_BASE, 'J');
}

Thank you,

Alphy

Hi sir, 

Thank you for your quick reply.

I am having some doubts about the changes you mentioned.

1. The slave ends up not seeing the correct ending to the burst command and instead NAK's the first byte of data sent which halts the transmission.

Sir, Please explain me what are the changes I need to do in the slave code to make it work properly .

2. Send all data with BURST and then receive all data with BURST. If this is done, I recommend using a header byte to inform the slave of how many bytes to expect so you can make sure you receive all the needed data.

I am trying to use this method. please explain me sir, how I can implement the header byte logic.

Thank you,

Alphy

Hi sir,

Thank you so much for supporting me to resolve the issue.

I red the document you gave and it gives a better understanding for me. After reading the document I got a clear picture about the steps I need to follow for a proper communication.

once again Thank you so much for your help.

Without using header byte logic I did my communication. Still I am not understanding how I can implement header byte logic.

Header byte logic is simple, just have the first byte or two of every packet you send be the amount of data sent. This is the place where I am confusing.I am not getting how I can send the amount of data in a header byte.

If you don't mind, please explain it using an example.

Thank you,

Alphy