// * imu_init *****************************************************************
// * Setup pins and I2C interface to communicate with IMU (Pololu MinIMU-9). *
// * *
// * NOTE: Also called internally by imu_i2c_abort_transaction during reset *
// * to recover from NAK/error. *
// * *
// * Portions for initialization of softi2c library copied/modified from *
// * "soft_i2c_atmel.c" example code. *
// ****************************************************************************
void imu_init(void)
{
// setup pins for I2C--------------------
SysCtlPeripheralEnable(IMU_PORT); // enable GPIO port for IMU
SysCtlPeripheralEnable(IMU_TIM); // enable timer to use for I2C bit timing
SysCtlPeripheralReset(IMU_TIM); // reset timer to clear any previous configuration
GPIOPinTypeI2C(IMU_PORT_BASE, IMU_PINS); // configure pins for I2C
memset(&g_sI2C, 0, sizeof(g_sI2C)); // clear record
SoftI2CCallbackSet(&g_sI2C, imu_SoftI2CCallback); // set callback function
SoftI2CSCLGPIOSet(&g_sI2C, IMU_PORT_BASE, IMU_SCL); // set SCL pin
SoftI2CSDAGPIOSet(&g_sI2C, IMU_PORT_BASE, IMU_SDA); // set SDA pin
SoftI2CInit(&g_sI2C); // initialize software I2C driver
SoftI2CIntEnable(&g_sI2C); // enable callback from softi2c
// configure timer interrupt
// Note, (interrupt rate)/4 = SCL frequency
TimerConfigure(IMU_TIM_BASE, TIMER_CFG_32_BIT_PER); // configure timer for 32b operation
TimerLoadSet(IMU_TIM_BASE, TIMER_A, SysCtlClockGet() / IMU_TIM_INTRATE);
// configure divider to yield desired interrupt rate
TimerIntEnable(IMU_TIM_BASE, TIMER_TIMA_TIMEOUT); // enable timer wrap interrupt
TimerEnable(IMU_TIM_BASE, TIMER_A); // enable timer to start counting
IntEnable(IMU_TIM_INT_VECT); // enable interrupt vector in NVIC
}
//*****************************************************************************
//
// This example demonstrates the use of the SoftI2C module to read and write an
// Atmel AT24C08A EEPROM.
//
//*****************************************************************************
int
main(void)
{
uint8_t pui8Data[16];
uint32_t ui32Idx;
//
// Set the clocking to run directly from the external crystal/oscillator.
// TODO: The SYSCTL_XTAL_ value must be changed to match the value of the
// crystal on your board.
//
SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_16MHZ);
//
// For this example, PortB[3:2] are used for the SoftI2C pins. GPIO port B
// needs to be enabled so these pins can be used.
// TODO: change this to whichever GPIO port(s) you are using.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
//
// For this example, Timer0 is used for the SoftI2C time base. This timer
// needs to be enabled before it can be used.
// TODO: change this to whichever timer you are using.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);
//
// Configure the appropriate pins to be I2C instead of GPIO.
//
GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_2 | GPIO_PIN_3);
//
// Initialize the SoftI2C module, including the assignment of GPIO pins.
// TODO: change this to whichever GPIO pins you are using.
//
memset(&g_sI2C, 0, sizeof(g_sI2C));
SoftI2CCallbackSet(&g_sI2C, SoftI2CCallback);
SoftI2CSCLGPIOSet(&g_sI2C, GPIO_PORTB_BASE, GPIO_PIN_2);
SoftI2CSDAGPIOSet(&g_sI2C, GPIO_PORTB_BASE, GPIO_PIN_3);
SoftI2CInit(&g_sI2C);
//
// Enable the SoftI2C interrupt.
//
SoftI2CIntEnable(&g_sI2C);
//
// Configure the timer to generate an interrupt at a rate of 40 KHz. This
// will result in a I2C rate of 10 KHz.
// TODO: change this to whichever timer you are using.
// TODO: change this to whichever I2C rate you require.
//
TimerConfigure(TIMER0_BASE, TIMER_CFG_PERIODIC);
TimerLoadSet(TIMER0_BASE, TIMER_A, SysCtlClockGet() / 40000);
TimerIntEnable(TIMER0_BASE, TIMER_TIMA_TIMEOUT);
TimerEnable(TIMER0_BASE, TIMER_A);
//
// Enable the timer interrupt.
// TODO: change this to whichever timer interrupt you are using.
//
IntEnable(INT_TIMER0A);
//
// Set up the serial console to use for displaying messages. This is
// just for this example program and is not needed for SoftI2C operation.
//
InitConsole();
//
// Display the example setup on the console.
//
UARTprintf("SoftI2C Atmel AT24C08A example\n");
//
// Write a data=address pattern into the first 16 bytes of the Atmel
// device.
//
UARTprintf("Write:");
for(ui32Idx = 0; ui32Idx < 16; ui32Idx++)
{
pui8Data[ui32Idx] = ui32Idx;
UARTprintf(" %02x", pui8Data[ui32Idx]);
}
UARTprintf("\n");
AtmelWrite(pui8Data, 0, 16);
//
// Read back the first 16 bytes of the Atmel device.
//
AtmelRead(pui8Data, 0, 16);
UARTprintf("Read :");
for(ui32Idx = 0; ui32Idx < 16; ui32Idx++)
{
UARTprintf(" %02x", pui8Data[ui32Idx]);
}
UARTprintf("\n");
//
// Tell the user that the test is done.
//
UARTprintf("Done.\n\n");
//
// Return no errors.
//
return(0);
}
