Patrick Witting

I2C example problem LPC1549

Discussion created by Patrick Witting on Jun 22, 2016

Hi guys,


i wasn't sure if this belongs to the LPCOpen or the LPC15xx forum.

I got the following problem:

I am using the example code or the I2C master interrupt mode of LPCopen on the OM13056 Evalboard (LPC1549 processor). The configuration of the I2C stays the same like the example (Clk_Div = 40 -> 72MHz/40 = 1.8MHz,Bus Speed = 100kHz). In the operation i just want to read 2 Bytes of data (no writing).


The init function:

void Init_I2C_Drucksensor(void) {   I2C_Xfer.slaveAddr = AG4_Sens_ADR; //Adr. des sensor   I2C_Xfer.status = 0; //Status auf 0   I2C_Xfer.txSz = 0; //es wird nichts geschrieben   I2C_Xfer.txBuff = NULL; //Buffer fürs schreiben auf null zeigen       Chip_IOCON_PinMuxSet(LPC_IOCON, PORT_0, PIN_22, (IOCON_DIGMODE_EN | I2C_Mode));   Chip_IOCON_PinMuxSet(LPC_IOCON, PORT_0, PIN_23, (IOCON_DIGMODE_EN | I2C_Mode));   Chip_SWM_EnableFixedPin(SWM_FIXED_I2C0_SCL);   Chip_SWM_EnableFixedPin(SWM_FIXED_I2C0_SDA);     Chip_I2C_Init(LPC_I2C0);     Chip_I2C_SetClockDiv(LPC_I2C0, I2C_CLK_Div);     //Chip_I2CM_SetBusSpeed(LPC_I2C0, I2C_400kHz_Speed);   Chip_I2CM_SetBusSpeed(LPC_I2C0, I2C_100kHz_Speed);     Chip_I2CM_Enable(LPC_I2C0);     NVIC_EnableIRQ(I2C0_IRQn);   NVIC_ClearPendingIRQ(I2C0_IRQn); }


The function to read out the data:

uint16_t ReadPres(void)  { uint8_t RohDaten[Pressure_Data_Size], StatusVal; uint16_t Pressure = 0, Buffer = 0;;    //Auslesen des Sensors via I2C    I2C_Xfer.rxSz = Pressure_Data_Size;  //Menge an empfangenen Bytes  I2C_Xfer.rxBuff = RohDaten;    //Buffer zum empfangen    #ifndef I2C_Polling_Mode   Chip_I2CM_Xfer(LPC_I2C0, &I2C_Xfer); Chip_I2C_EnableInt(LPC_I2C0, (I2C_INTENSET_MSTPENDING | I2C_INTENSET_MSTRARBLOSS | I2C_INTENSET_MSTSTSTPERR));   while (I2C_Xfer.status == I2CM_STATUS_BUSY) {__WFI();}   Chip_I2C_ClearInt(LPC_I2C0, (I2C_INTENSET_MSTPENDING | I2C_INTENSET_MSTRARBLOSS | I2C_INTENSET_MSTSTSTPERR));     #else    Chip_I2CM_XferBlocking(LPC_I2C0, &I2C_Xfer);    //ReadI2C(AG4_Sens_ADR, RohDaten, Pressure_Data_Size);   #endif   //Verarbeiten der Daten   StatusVal = (RohDaten[0]>>6) & 0x03;   if(StatusVal == 0)  {  Buffer = ((RohDaten[0]<<8) | (RohDaten[1])) & 0x3FFF;  Pressure = Buffer*3 + (Buffer/10)*3 + (Buffer/100)*9 + (Buffer/1000)*1;     }else{    Buffer = ((RohDaten[0]<<8) | (RohDaten[1])) & 0xC000;  //Rückgabe der Fehlermeldung    Pressure = Buffer;    }    return Pressure; }


The sampling rate is controlled by the RIT (Interrupt every 1ms -> all 10ms getting a new sample).

I tried the code in interrupt mode (default) and in polling mode.


In interrupt mode i stuck at the line in the reading function:

while (I2C_Xfer.status == I2CM_STATUS_BUSY) {__WFI();}


At the polling mode at the line where the status gets requested.

If i meassure on the Pins there is no activity. So i think the data is never written and that's the reason why the status never changes to OK or something else.

But i don't have any idea why this is so, so i appreciate all kind of help/information.


Best regards