int adr= LSM303_ADDRESS_ACCEL;
int reg= LSM303_REGISTER_ACCEL_CTRL_REG1_A;
unsigned char value=0x27;
const unsigned char buf[] = {static_cast <unsigned char > (reg),value};
periph::blk::tx_transfer tran(buf,sizeof buf);
i2c1.transaction(adr, tran);