Stellaris I2C Bus Scanner

busscan.c

//*****************************************************************************
//
//! Probes the selected I2C bus for available slave devices
//!
//! \param ulI2CBase is the base for the I2C module.
//!
//! This function scans the selected I2C bus for available I2C slave device.
//! The ulI2CBase parameter is the I2C modules master base address.
//! \e ulI2CBase parameter can be one of the following values:
//!
//! - \b I2C0_MASTER_BASE
//! - \b I2C1_MASTER_BASE
//! - \b I2C2_MASTER_BASE
//! - \b I2C3_MASTER_BASE
//!
//! \return 0 if there was an error or 1 if there was not.
//
//*****************************************************************************


#include "stdint.h"
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/pin_map.h"
#include "driverlib/i2c.h"
#include "driverlib/gpio.h"
#include "driverlib/sysctl.h"
#include "driverlib/rom.h"
#include "driverlib/rom_map.h"
#include "utils/uartstdio.h"


#define MPU6050_ADDRESS 0x68
//#define MPU6050_ADDRESS 0x69
#define HMC5883_ADDRESS 0x1E
#define MS561101BA_ADDRESS 0x77
//#define MS561101BA_ADDRESS 0x76


unsigned long I2CBusScan(unsigned long ulI2CBase) {
    unsigned char ucProbeAdress;
    unsigned long ucerrorstate;

    //
    // Check the arguments.
    //
    //ASSERT(I2CMasterBaseValid(ulI2CBase));

    //
    // Wait until master module is done transferring.
    //
    UARTprintf("ROM_I2CMasterBusy\n");

    while(ROM_I2CMasterBusy(ulI2CBase)){};


    UARTprintf("Probing...\n");

    //
    // I2C Addresses are 7-bit values
    // probe the address range of 0 to 127 to find I2C slave devices on the bus
    //
    for (ucProbeAdress = 0; ucProbeAdress < 127; ucProbeAdress++) {
        //
        // Tell the master module what address it will place on the bus when
        // writing to the slave.
        //
        ROM_I2CMasterSlaveAddrSet(ulI2CBase, ucProbeAdress, false);
        ROM_SysCtlDelay(50000);

        //
        // Place the command to be sent in the data register.
        //
        ROM_I2CMasterDataPut(ulI2CBase, 0x00);

        //
        // Initiate send of data from the master.
        //
        ROM_I2CMasterControl(ulI2CBase, I2C_MASTER_CMD_BURST_SEND_START);

        //
        // Make some delay
        //
        ROM_SysCtlDelay(500000);

        //
        // Read the I2C Master Control/Status (I2CMCS) Register to a local
        // variable
        //
        ucerrorstate = ROM_I2CMasterErr(ulI2CBase);

        //
        // Examining the content I2C Master Control/Status (I2CMCS) Register
        // to see if the ADRACK-Bit (Acknowledge Address) is TRUE (1)
        // ( 1: The transmitted address was not acknowledged by the slave)
        //
        if(ucerrorstate & I2C_MASTER_ERR_ADDR_ACK)
        {
            //
            // device at selected address did not acknowledge --> there's no device
            // with this address present on the I2C bus
            //
            //
            // Print a message to Stdio
            //
            UARTprintf("Address not found: 0x%2x - %3d\n",ucProbeAdress,ucProbeAdress);
            //
            // Make some delay
            //
            ROM_SysCtlDelay(1500000);

            //
            // ( 0: The transmitted address was acknowledged by the slave)
            //
        } else {
            //
            // device at selected address acknowledged --> there is a device
            // with this address present on the I2C bus
            //
            //
            // Print a message to Stdio
            //
            UARTprintf("Address found: 0x%2x - %3d\n",ucProbeAdress,ucProbeAdress);

            //
            // Make some delay
            //
            ROM_SysCtlDelay(1500000);
        }
    }

    //
    // End transfer of data from the master.
    //
    ROM_I2CMasterControl(ulI2CBase, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);

    //
    // Print a message to Stdio
    //
    UARTprintf("I2C Bus-Scan done...\n");

    //
    // Return 1 if there is no error.
    //
    return 1;
}


int main(void) {
    // Enable FPU for interrupt routines
    // ROM_FPULazyStackingEnable();
    // ROM_FPUEnable();

    // Set clock to 80MHz
    SysCtlClockSet(SYSCTL_SYSDIV_2_5 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);

    // Turn off LEDs
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
    ROM_GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);
    ROM_GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2|GPIO_PIN_3, 0);

    // Setup I2C on PB2 & PB3 (I2C0)
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
    ROM_GPIOPinConfigure(GPIO_PB2_I2C0SCL);
    ROM_GPIOPinConfigure(GPIO_PB3_I2C0SDA);
    ROM_GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_2 | GPIO_PIN_3);
    ROM_I2CMasterInitExpClk(I2C0_MASTER_BASE, SysCtlClockGet(), false);
    ROM_I2CMasterEnable(I2C0_MASTER_BASE);

    // I2C doesn't seem to work without this with the MPU-6050
    // Found it at http://e2e.ti.com/support/microcontrollers/stellaris_arm_cortex-m3_microcontroller/f/473/p/169023/639164.aspx#639164
    ROM_GPIOPadConfigSet(GPIO_PORTB_BASE, GPIO_PIN_2, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD);
    ROM_GPIOPadConfigSet(GPIO_PORTB_BASE, GPIO_PIN_3, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_OD_WPU);

    // Initialize the UART.
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
    ROM_GPIOPinConfigure(GPIO_PA0_U0RX);
    ROM_GPIOPinConfigure(GPIO_PA1_U0TX);
    ROM_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
    UARTStdioInit(0);

    UARTprintf("I2C Bus-Scan starting...\n");


    // Start probing sensors
    ROM_GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, GPIO_PIN_3);
    I2CBusScan(I2C0_MASTER_BASE);

    ROM_GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);
    
    UARTprintf("I2C Bus-Scan complete\n");

    return 0;
}