S1_ENI
pcf8584_put_s1(i2c, S1_START2 | S1_ENI);
pcf8584_put_s1(i2c, S1_ESO | S1_ENI);
pcf8584_put_s1(i2c, S1_ESO | S1_ENI);
pcf8584_put_s1(i2c, S1_START2 | S1_ENI);
pcf8584_put_s1(i2c, S1_START | S1_ENI);