Method readBitsW

lib/i2cdev/I2Cdev.cpp:162–177

Read multiple bits from a 16-bit device register. * @param devAddr I2C slave device address * @param regAddr Register regAddr to read from * @param bitStart First bit position to read (0-15) * @param length Number of bits to read (not more than 16) * @param data Container for right-aligned value (i.e. '101' read from any bitStart position will equal 0x05) * @param timeout Optional read timeo

 * @return Status of read operation (1 = success, 0 = failure, -1 = timeout)
 */
int8_t I2Cdev::readBitsW(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint16_t *data, uint16_t timeout, void *wireObj) {
    // 1101011001101001 read byte
    // fedcba9876543210 bit numbers
    //    xxx           args: bitStart=12, length=3
    //    010           masked
    //           -> 010 shifted
    uint8_t count;
    uint16_t w;
    if ((count = readWord(devAddr, regAddr, &w, timeout, wireObj)) != 0) {
        uint16_t mask = ((1 << length) - 1) << (bitStart - length + 1);
        w &= mask;
        w >>= (bitStart - length + 1);
        *data = w;
    }
    return count;
}

/** Read single byte from an 8-bit device register.
 * @param devAddr I2C slave device address