Re: [Gumstix-users] Unusually Long Delay for ATMega128

[<fo...@it...>]

Hi Michael,

> I2C doesn't know about 16-bit things.
> So how are you splitting your value and reassembling it?

Thanks for pointing this out.  Here is what I am now doing to split my value:

// *****************************************************************
// < In i2c-Sensor-io.h
typedef struct
{
    uint8_t 	SensorIdx;    ///< Index of the sensor to be read.
    uint8_t 	Sts;		  ///< Status of the Read command
    uint8_t 	distH;		  ///< High byte of distance value returned by the
sensor.
    uint8_t 	distL;		  ///< Low byte of distance value returned by the
sensor.
} I2C_IO_TrgrPing_Snsr_t;

#define I2C_IO_TRGR_PING_SNSR     0x21

// *****************************************************************
//< In I2C-Sensor-io-api.c
int I2C_IO_Trgr_PING_Snsr( int i2cDev, uint8_t SensorIdx, uint16_t* range,
uint8_t* status )
{
	uint8_t             		bytesRead = 0;
	I2C_IO_TrgrPing_Snsr_t		trgrPing;
	trgrPing.SensorIdx = SensorIdx;
	if ( I2cProcessBlock( i2cDev, I2C_IO_TRGR_PING_SNSR, &SensorIdx, sizeof(
SensorIdx ), &trgrPing, sizeof( trgrPing ), &bytesRead ) != 0 )
    {
        LogError( "I2C_IO_Trgr_PING_Sensor: I2cProcessBlockFailed: %s
(%d)\n", strerror( errno ), errno );
        return FALSE;
    }
    *range = trgrPing.distH;
    *range = (*range << 8) + trgrPing.distL;
    *status = trgrPing.Sts;
    return TRUE;
} // I2C_IO_Trgr_PING_Sensor

// *****************************************************************
// < In I2C-Sensor.c (runs on the robostix).  Part of my ProcessCommand()
//    function.
case I2C_IO_TRGR_PING_SNSR:
{
    uint8_t *snsrIdx = (uint8_t *)&packet->m_data[2];
    PingStatus[*snsrIdx] = ReadPingSensor( *snsrIdx, Dist );
    I2C_IO_TrgrPing_Snsr_t *trgr = (I2C_IO_TrgrPing_Snsr_t
*)&packet->m_data[ 1 ];  // +1 for cmd, +1 for len
    trgr->SensorIdx = *snsrIdx;
    trgr->Sts = PingStatus[*snsrIdx];
    trgr->distH = (( Dist[*snsrIdx] >> 8 ) & 0xFF );
    trgr->distL = (  Dist[*snsrIdx]        & 0xFF );
    packet->m_data[ 0 ] = sizeof( *trgr );
    return sizeof( *trgr ) + 1; // + 1 for len;
}
// *****************************************************************

Daniel