Write to multiple I2C devices at the same time
All devices share the same SD SC bus with Rpullup and C load on cables.  

THere is no apparent reason why each device cannot use the same address and data and decode at same time as long as all timing and V specs are maintained if there is no ACK on SCCB.

Choose R pullup for 3 mA then R*C load affects slew rate and noise rejection.
Since driver has internal RdsOn &lt;100 ohm this raises Vol slightly  when smaller R pullups are used .  Optimum R pullup is when you have balanced noise margin outside logic input threshold of  30% Vdd and 70% Vdd thresholds for Vol, Voh.

details

e.g. if driver is 100R ESR or Rdson Low and Rpullup to 1.8V is 500 Ohms then 3.0mA for Iol (1.8V/(100R+500R)=3.0mA)  So you may adjust R pullup from this starting point.  THen probe correctly with short 10:1 probe pins to avoid >10MHz ringing) or use diff. probes or two 10:1 calibrated probes A-B with flatline on A-B to same signal then if OK, move one probe pin to gnd pin beside SD , SC test pins.  ALways include test pins + gnd pin &lt; 1cm apart.

Choice of cable capacitance and length determines C load. usually 60pF/m for ribbon or twisted pair and higher if shielded.  If rise time at 400kHz is too slow then switched R Pullup method may be used.