Listing 2. Transmit Command Sequence

void writeSHT1xCommand(int iMode)
{
    unsigned char  ucBitToCheck;
    unsigned char  ucAckBit;

    driveDataLine(DATA_SHT);
    /* All 3 address bits always zero
     * so start with those */
    writeSHT1xZero(DATA_SHT);
    udelay(2);
    writeSHT1xOne(SCK_SHT);
    udelay(2);
    writeSHT1xZero(SCK_SHT);

    writeSHT1xZero(DATA_SHT);
    udelay(2);
    writeSHT1xOne(SCK_SHT);
    udelay(2);
    writeSHT1xZero(SCK_SHT);

    writeSHT1xZero(DATA_SHT);
    udelay(2);
    writeSHT1xOne(SCK_SHT);
    udelay(2);
    writeSHT1xZero(SCK_SHT);

    /* Now transmit the 5 command bits,
     * in the order of MSb to LSb */
    for (ucBitToCheck=0x10; ucBitToCheck != 0;)
    {
        if (iMode & ucBitToCheck)
            writeSHT1xOne(DATA_SHT);
        else
            writeSHT1xZero(DATA_SHT);
        udelay(2);
        writeSHT1xOne(SCK_SHT);
        udelay(2);
        writeSHT1xZero(SCK_SHT);
        ucBitToCheck >>= 1;
    }

    /* Now tri-state the data DIO so the
     * device can ACK the transfer */
    tristateDataLine(DATA_SHT);
    udelay(2);
    writeSHT1xOne(SCK_SHT);
    udelay(2);
    ucAckBit = readSHT1x(DATA_SHT);
    writeSHT1xZero(SCK_SHT);
    mdelay(250);
}