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PSoC™ 5, 3 & 1 Forum Discussions

alro_2373731
Level 1
Level 1

I have created an i2c project like the given example but I see a delay on the read buffer thats returned to the master.  Its returns the correct buffer on subsequent requests.  For example using the bridge control gui. I send a start with a write address and a sub command... then send a repeated start with a read and returns blank on the first command.  It appears from the datasheet that the function I2C_SlaveInitReadBuf has a side effect of "If this function is called during a bus transaction, data from the previous buffer location and the beginning of the current buffer may be transmitted."  This seems exactly what I am doing with a repeated start.

s 10 0A s 11 x x p

The first time run it returns

s 10+ 0A+ s 11+ 00+ 00+ p

then any following command reads

s 10+ 0A+ s 11+ 00+ 04+ p

Do I need to run a command after I set the return buffer variable?

#include <project.h>

#include <stdio.h>

#include <header01.h>

/* I2C slave read and write buffers */

uint8 i2cReadBuffer[7];

uint8 i2cWriteBuffer[7];

uint16 i2cbuffer;

int main()

{

    CyGlobalIntEnable; /* Enable global interrupts. */

    CyWdtStart(CYWDT_1024_TICKS,CYWDT_LPMODE_NOCHANGE);

    /* Start I2C slave (SCB mode) */

    I2C_1_Start();

    I2C_1_SlaveInitReadBuf(i2cReadBuffer,  7);

    I2C_1_SlaveInitWriteBuf(i2cWriteBuffer, 7);

    int32 temperature = 0;

    for(;;)

    {

        CyWdtClear();

    

    

        /* Write complete: parse command packet */

        if (0u != (I2C_1_SlaveStatus() & I2C_1_SSTAT_WR_CMPLT))

        {

            ExecuteWriteCommand(i2cWriteBuffer[0], i2cWriteBuffer);

        

            /* Clear slave write buffer and status */

            I2C_1_SlaveClearWriteBuf();

            (void) I2C_1_SlaveClearWriteStatus();

        }

        /* Read complete: expose buffer to master */

        if (0u != (I2C_1_SlaveStatus() & I2C_1_SSTAT_RD_CMPLT))

        {

            /* Clear slave read buffer and status */

            I2C_1_SlaveClearReadBuf();

            (void) I2C_1_SlaveClearReadStatus();

        }

    }

}

/*******************************************************************************

* ExecuteCommand(): executes received command and returns status

*******************************************************************************/

void ExecuteWriteCommand(uint32 cmd, uint8_t *buffer)

{

    int16 return_value;

    /* Execute received command */

    switch (cmd)

    {

  

        case 0x0A:

            return_value = 4;

            i2cReadBuffer[0] = (return_value & 0xFF00) >> 8 ;

            i2cReadBuffer[1] = (return_value & 0x00FF);

      

        default:

        

            break;

    }

}

/* [] END OF FILE */

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AnkitaS_51
Employee
100 likes received 50 likes received 25 likes received
Employee

Please provide us with your project

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