I2C communication problem on TM4C123G launchpad

Hi Bijendra,

That the SCL line stays high would suggest you have pull-up resistors installed on the I2C bus - but please confirm this is the case. Also, the first thing you should do if you suspect pin malfunctioning is to turn that pin to a regular GPIO and toggle it "manually" - verifying operation with your scope. Or, it might be that your code actually never gets to the first I2CMasterControl line - have you checked with the debugger?

Also, a couple of notes:

1. The parameters for GPIOPinConfigure - you have the macro names commented out and replaced with values - why? The macro names should be just fine. If the compiler complains they're undefined, you need to ensure pin_map.h is correctly included
2. Your first call to I2CMasterDataPut - you give 0x400 as the value. I assume your intention is to send the two-byte EEPROM memory address there. Do understand that (if the code worked) what would get sent would be 0x00 only - you need two subsequent calls, one with 0x00 and one with 0x04. Check the EEPROM datasheet for the proper order of those bytes.

Regards,

Veikko

Hi Veikko,

thanks for quick reply,

Also, the first thing you should do if you suspect pin malfunctioning is to turn that pin to a regular GPIO and toggle it "manually" - verifying operation with your scope. Or, it might be that your code actually never gets to the first I2CMasterControl line - have you checked with the debugger?

GPIO pin is toggling properly and tested with Scope.

it might be that your code actually never gets to the first I2CMasterControl line - have you checked with the debugger?

 I haven't tested it because Energia IDE don't have any debugger. is there any other way to test it?

 The parameters for GPIOPinConfigure - you have the macro names commented out and replaced with values - why? The macro names should be just fine. If the compiler complains they're undefined, you need to ensure pin_map.h is correctly included

i already included pin_map.h but still i got same error. so instead of solving it, i simply tried replace macro name with macro value  to get work done.

Your first call to I2CMasterDataPut - you give 0x400 as the value. I assume your intention is to send the two-byte EEPROM memory address there. Do understand that (if the code worked) what would get sent would be 0x00 only - you need two subsequent calls, one with 0x00 and one with 0x04. Check the EEPROM datasheet for the proper order of those bytes.

thank you for pointing this.

But still problem is same, nothing on i2c scl line bus never goes low.

Bijendra Singh said:

it might be that your code actually never gets to the first I2CMasterControl line - have you checked with the debugger?

 I haven't tested it because Energia IDE don't have any debugger. is there any other way to test it?

You could switch on the onboard LED's - one colour just before the call, another just after, for example.

Bijendra Singh said:

you need to ensure pin_map.h is correctly included

i already included pin_map.h but still i got same error. so instead of solving it, i simply tried replace macro name with macro value  to get work done.

I would suggest you stop work until you've resolved this - things like this usually mean there's something more fundamental wrong with your project and can cause unexpected, nasty side effects. Always ensure a stable foundation before you start laying bricks on top! I have not worked on Energia so I can't unfortunately guide you there.

Bijendra Singh said:

is there any problem in code ?

Not anything that I spot outright - but I didn't compare to a known-good code, and it's been a while since I've last fiddled with plain I2C. A good suggestion would be to look at the I2C examples included in the TivaWare package.

thank you.

little bit of success achieved.

but current is problem is that i2c scl and  line is keeping low.

kindly suggest how can i solve this.

below is current code.

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_gpio.h"
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/sysctl.h"
//#include "driverlib/pin_map.h"
#include "driverlib/gpio.h"
#include "driverlib/pwm.h"
#include "driverlib/i2c.h"
#include "driverlib/uart.h"

#define address 0x50

void sendDataTOPC(unsigned int qeiposition);
void delay(unsigned int ms)
{
	SysCtlDelay( (SysCtlClockGet()/(3*1000))*ms ) ;
}


int main(void)
{
  //pinMode(30, OUTPUT);
  //delay(200);
  // put your setup code here, to run once:
  SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC |   SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);
  SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
  SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);
  delay(10);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_UART7/*SYSCTL_PERIPH_UART0*/); // Enable UART hardware
  SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE/*SYSCTL_PERIPH_GPIOA*/); // Enable Pin hardware
  SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD); // Enable Pin hardware

  GPIOPinTypeI2CSCL(GPIO_PORTB_BASE, GPIO_PIN_2);
  GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_3);

  GPIOPinConfigure(/*GPIO_PB2_I2C0SCL*/0x00010803);
  GPIOPinConfigure(/*GPIO_PB3_I2C0SDA*/0x00010C03);

  GPIOPinConfigure(0x00040001/*GPIO_PC4_U4RX*/);
  GPIOPinConfigure(0x00040401/*GPIO_PC4_U4TX*/);

  GPIOPinTypeGPIOOutput(GPIO_PORTD_BASE, GPIO_PIN_3);
  GPIOPinWrite(GPIO_PORTD_BASE,GPIO_PIN_3,0);


   GPIOPinTypeUART(GPIO_PORTE_BASE, GPIO_PIN_0 | GPIO_PIN_1); // Set Pins for UART

  UARTConfigSetExpClk(UART7_BASE, SysCtlClockGet(), 115200, // Configure UART to 8N1 at 115200bps
  (UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE | UART_CONFIG_PAR_NONE));

  //GPIOPadConfigSet(GPIO_PORTB_BASE,GPIO_PIN_2,0x00000001,0x0000000A);


  //GPIOPadConfigGet(GPIO_PORTB_BASE, GPIO_PIN_2, &pui32Strength, &pui32PinType);
  UARTCharPut(UART7_BASE, 'E');
  //sendDataTOPC(pui32Strength);
  //sendDataTOPC(pui32PinType);
 GPIOPinTypeI2CSCL(GPIO_PORTB_BASE, GPIO_PIN_2);
 GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_3);

  I2CMasterInitExpClk(I2C0_BASE, 16000000, false);
  I2CMasterEnable(I2C0_BASE);
   I2CMasterSlaveAddrSet(I2C0_BASE, address, false);
   //I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);

//   while(I2CMasterBusy(I2C0_BASE) != false)
//  {
// //   digitalWrite(30, HIGH);
// //   delay(500);
// //   digitalWrite(30, LOW);
//  }

  I2CMasterDataPut(I2C0_BASE, 0x30);
 // I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_SEND);

  while(I2CMasterBusy(I2C0_BASE))
  {
  }
  I2CMasterDataPut(I2C0_BASE, 'B');
  I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_CONT);
  if(I2CMasterErr(I2C0_BASE) == I2C_MASTER_ERR_NONE)
  {
     I2CMasterDataPut(I2C0_BASE, 'B');
     I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_CONT);
     while(I2CMasterBusy(I2C0_BASE))
            {
            }
     I2CMasterDataPut(I2C0_BASE, 'I');
     I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_FINISH);
  }
  else
  {
    I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_ERROR_STOP);
  }
  return 0;
}

I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);

 is uncommented in the code,  and at the place of

I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_SEND);

i again replaces it with

I2CMasterControl(I2C0_BASE,I2C_MASTER_CMD_BURST_SEND_CONT); 

but still no success. i am clueless now....

Can you check if the line 

I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_ERROR_STOP)
is being executed.

I have had problems with this command and replaced it with BURST_SEND_FINISH
The ERROR_STOP caused both lines to go low I believe it was the slave that held the lines low.

Good luck
Claude