I2C Communications

You do not show any details, so a general tutorial may help https://learn.sparkfun.com/tutorials/i2c

If you prefer a video tutorial, Ben Hack made one:

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RE: I2C Communications RE: i2c vs spi 10 Useful Electronics Tutorials from Ben Heck Watch Ben Heck's Interfaces Tutorial -- Episode 78

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Depending on how serious you are with electronics, I can recommend buying a logic analyzer (some cheap cost a few dollars). Or, some microcontroller programmers have support for various protocols analysis (UART, I2C, SPI).

This allows you to test any new sensor/device with a piece of HW and SW that is proven to work and later makes it easier to debug your own HW and firmware. Almost all microcontroller families now have an integrated I2C module and most development environments have ready made libraries for it.

https://www.adafruit.com/product/1120  This is the board itself

https://cdn-shop.adafruit.com/datasheets/LSM303DLHC.PDF This is the datasheet

I am trying to read the magnetometer.

I have tried to use PSoC 4 kit in I2C to read the x axis values. When I am in debug mode in the PSoC creator I can't get any values returned when the device is being read. Every time I keep getting 0. The registers CRA_REG_M, CRB_REG_M, and MR_REG_M I beleive all need set for the calibration of the device. Am I correct in assuming this? Also is there a chance I have made a rookie mistake?

Thanks

I've quickly gone through the linked datasheet and I think you only have to properly set MR_REG_M register in order to start measuring. By default (after reset), it is in sleep-mode.

To be honest, I am also struggling with debugging PSoCs in PSOC Creator. Compared to debugging PICs, it is quite limited. (Must go deeper to make sure I am not using it wrong.)

That's why I recommended a logic analyser. You can easily read/write the entire memory of the sensor and quickly check all values against the datasheet.

If you are interested, I can insert some working I2C code for PSoC 5LP (it is probably the same for PSOC 4) I used for a real time clock.

Here is example http://www.psocdeveloper.com/project/psoc4-i2c-communication/

Yea I ordered a logic analyser yesterday so i'm waiting on it coming. If you have code I would love to compare it to what I have!

Thanks

The code below is the minimum I extracted from my project and should be general enough. I've worked with DS3232M RTC. The component name (placed in the design) is I2C and microcontroller used is some PSOC 5LP series.

I am not sure about the original source, but I think this code comes from a Cypress application note (I've just opened a few, but couldn't find it). This code doesn't check for I2C component availability etc. and as provided is useless (nothing is done with the data). I only pasted the functions to perform a single read from the I2C slave device.

#define I2C_WRITE 0u
#define I2C_READ 1u
#define RTC_I2C_ADDRESS 0x68 // I2C address of DS3232M (and some other RTCs)
#define RTC_RAM_TD_LOCATION 0u // RAM location of current time and date
#define RTC_NO_OF_BYTES_FULL 255u // number of bytes to read full RTC RAM

void RTC_I2C_Read_RAM (unsigned char ramLocation, unsigned char bytesCount, unsigned char *i2cBuffer) {
    I2C_MasterSendStart(RTC_I2C_ADDRESS, I2C_WRITE);
    I2C_MasterWriteByte(ramLocation);
    I2C_MasterReadBuf(RTC_I2C_ADDRESS, i2cBuffer, bytesCount, (I2C_MODE_REPEAT_START | I2C_MODE_COMPLETE_XFER));    
}

uint8 i2cRTCReadBufferFull[256]; // buffer big enough to store full RAM of RTC clock

int main(void)
{
    CyGlobalIntEnable; /* Enable global interrupts. */

    I2C_Start(); // start I2C component

    RTC_I2C_Read_RAM(RTC_RAM_TD_LOCATION, RTC_NO_OF_BYTES_FULL, i2cRTCReadBufferFull); // read the whole RAM of DS3232M

 for(;;) {;}
}

I have a funny feeling I am reading the device wrong or else not sending the correct device data.

#define MAG_ADDR (0x1E) // magnetometer 7 bit address

#define MAG_ADDR_Read (0x1E | 0x01) // magnetometer 8 bit address

#define MAG_ADDR_Write (0x1E | 0x00) // magnetometer 8 bit address

#define CRA_ADDR (0x00) // Control Register A

#define CRB_ADDR (0x01) // Control Register B

#define MR_ADDR (0x02) // Mode Register

#define X_AXIS_H (0x03)

#define X_AXIS_L (0x04)

/////////////////////////////////////////////////////////////////// i2c.c containing i2c functions //////////////////////////////////////////////////////////////

uint8 mag_ReadReg(uint8 Reg){

    uint8 Write_Buf[1] = {0}; //buffer that contains the register we want to read from

    Write_Buf[0] = Reg;

    uint8 Read_Buf[1] = {0};

    // step 1

    I2C_1_I2CMasterWriteBuf(MAG_ADDR, (uint8 *)Write_Buf, 1, I2C_1_I2C_MODE_NO_STOP);

    while((I2C_1_I2CMasterStatus() & I2C_1_I2C_MSTAT_WR_CMPLT) == 0){}

    // step 2

    I2C_1_I2CMasterReadBuf(MAG_ADDR, (uint8 *)Read_Buf, 1, I2C_1_I2C_MODE_REPEAT_START);

    while((I2C_1_I2CMasterStatus() & I2C_1_I2C_MSTAT_RD_CMPLT) == 0){}

    return Read_Buf[0];

}

// step(1) the register address that you write to

//     (2) the value you wish to write to the register

void mag_WriteReg(uint8 Reg, uint8 value){

    uint8 Write_Buf[2]={0};

    Write_Buf[0] = Reg; // register to write to

    Write_Buf[1] = value; // value to write to register

    I2C_1_I2CMasterWriteBuf(MAG_ADDR, (uint8 *)Write_Buf, 2, I2C_1_I2C_MODE_COMPLETE_XFER);

    while((I2C_1_I2CMasterStatus() & I2C_1_I2C_MSTAT_WR_CMPLT) == 0){}

    return;

}

///////////////////////////////////////////////////////////////main.c//////////////////////////////////////////////////////

int main(void)

{

    I2C_1_Start();

    CyGlobalIntEnable; /* Enable global interrupts. */

    uint8 deviceID[1]={0};

    uint8 CRA_Before, CRA_After, CRB_Before;

    CRA_Before = mag_ReadReg(CRA_ADDR); //register before written to

    mag_WriteReg(MR_ADDR, 0x00); // register written to

    CRA_After = mag_ReadReg(CRA_ADDR); // register after written to

    for(;;)

    {

        deviceID[0] = mag_ReadReg(MR_ADDR);

    }

}

I keep trying to watch the variables CRA_BEFORE and CRA_AFTER to see is the register has changed. I keep getting <optimized out> in the watch window where there should be values.

I found out my problem. All is working now! Thank Goodness