Hi Team,
Customer is trying to communicate on an TI launchpad via i2c with a GPS Receiver and encountering issue with the i2c. Please see details below.
For the initialization and the communication aim using the TIVA ware Library. The TI Launchpad is the Master and the GPS receiver is the Slave.
SYS_RESLT sys_I2cInitFunc(uint32_t g_ui32SysClock){
SYS_RESLT eFault = SYS_RESLT__OK;
//
// Stop the Clock, Reset and Enable I2C Module
// in Master Function
//
SysCtlPeripheralDisable(SYSCTL_PERIPH_I2C0);
SysCtlPeripheralReset(SYSCTL_PERIPH_I2C0);
SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);
//
// Wait for the I2C0 module to be ready.
//
while (!SysCtlPeripheralReady(SYSCTL_PERIPH_I2C0))
{
}
//
//Enable GPIO for Configuring the I2C Interface Pins
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
//
// Wait for the Peripheral to be ready for programming
//
while (!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOB))
{
};
//
// Configure Pins for I2C2 Master Interface
//
GPIOPinConfigure(GPIO_PB2_I2C0SCL);
GPIOPinConfigure(GPIO_PB3_I2C0SDA);
GPIOPinTypeI2C(GPIO_PORTB_AHB_BASE, GPIO_PIN_3);
GPIOPinTypeI2CSCL(GPIO_PORTB_AHB_BASE, GPIO_PIN_2);
//
// Initialize Master
//
I2CMasterInitExpClk(I2C0_BASE,g_ui32SysClock, false);
return eFault;}
the Parameter g_ui32SysClock is the System Clock frequency.
Then I have a Function wich I use to read.
SYS_RESLT gps_readByteI2C(uint8_t *pbBytesRead, uint8_t bLen){
SYS_RESLT eFault = SYS_RESLT__OK;
uint8_t bAdd = GPS_I2C_ADD
;
uint8_t bI = 0;// read only one byte
if (bLen == 1){ // wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// set i2c address and read
I2CMasterSlaveAddrSet(I2C0_BASE, bAdd, true);
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// read on the bus
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_RECEIVE);
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// check fault
if (I2CMasterErr(I2C0_BASE) != I2C_MASTER_ERR_NONE)
{
eFault = SYS_RESLT__I2C; // fault
}
while (I2CMasterBusy(I2C0_BASE))
{
}
// read data
*pbBytesRead = I2CMasterDataGet(I2C0_BASE);
}
else // more then one byte to read
{
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// set i2c address and read
I2CMasterSlaveAddrSet(I2C0_BASE, bAdd, true);
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// read on the bus first byte
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_RECEIVE_START);
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// check fault
if (I2CMasterErr(I2C0_BASE) != I2C_MASTER_ERR_NONE)
{
//test = I2CMasterErr(I2C0_BASE);
eFault = SYS_RESLT__I2C; // fault
}
while (I2CMasterBusy(I2C0_BASE))
{
}
// get data
pbBytesRead[0] = I2CMasterDataGet(I2C0_BASE);
// for all othe bytes
for (bI = 0; bI < bLen - 2; bI++)
{
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// set i2c address and read
I2CMasterSlaveAddrSet(I2C0_BASE, bAdd, true);
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// read on the bus
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_RECEIVE_CONT);
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// check fault
if (I2CMasterErr(I2C0_BASE) != I2C_MASTER_ERR_NONE)
{
eFault = SYS_RESLT__I2C; // fault
}
while (I2CMasterBusy(I2C0_BASE))
{
}
// get data
pbBytesRead[bI + 1] = I2CMasterDataGet(I2C0_BASE);
// break if new message
if (pbBytesRead[bI + 1] == 0x24)
{
break;
}
}
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// set i2c address and read
I2CMasterSlaveAddrSet(I2C0_BASE, bAdd, true);
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// read on the bus last byte
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);
// wait
while (I2CMasterBusy(I2C0_BASE))
{
}
// check fault
if (I2CMasterErr(I2C0_BASE) != I2C_MASTER_ERR_NONE)
{
eFault = SYS_RESLT__I2C; // fault
}
while (I2CMasterBusy(I2C0_BASE))
{
}
// get data
pbBytesRead[bI + 1] = I2CMasterDataGet(I2C0_BASE);
}
return eFault;}I Use a logic Analyzer to watch the i2c bus an there everything seams fine the message is correct and look like it should be. so I think the Problem is not the slave. the Problem is that in pbBytesRead are most of the bytes tow ore more times. for example the logic analyzer says on the bus was : 0x24 0x42 0x45 0x76 0x64. but the launchepad reads in pbBytesRead : 0x24 0x24 0x24 0x42 0x42 0x45 0x45 0x45 0x76 0x76 0x76 0x64 0x64 0x64. maybe something with the init is wrong? Has anybody some clue or hint for me ? if needed I can provide some more information.
Thanks.
Regards,
May
Thank you.
Regards,
May
