Hello everyone!
I’m working on a project using the QwiicBus system (two Endpoints and one Midpoint) to transmit data from Sparkfun’s FS300-1015 Air Velocity Sensor Breakout (located inside a wind tunnel) to an Arduino R4 that’s about 20 feet away.
As recommended, I’d like to power all three PCA9615 VDDB pins with 5V. However, due to physical constraints and project rules, a 5V source cannot be placed near either endpoint*. I’m only allowed to place a 5V source near/at the midpoint! 
*Basically, it’s too difficult to bring a 5V source into the wind tunnel. The Arduino (which is itself a 5V source) can be near the terminating endpoint, but it must be optically isolated from that endpoint due to project requirements.
Given this limitation, what’s the best way to supply 5V at the midpoint and ensure it reaches the VDDB pins on all three boards?
Here are two approaches I’m considering:
Option 1:
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Supply 5V to the midpoint’s VCC2 pin
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Close both sides of the midpoint’s PSEL jumper, effectively shorting VCC2 and VCC1
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Open the midpoint’s BP jumper to isolate VCC1 & VCC2 from the midpoint’s 3.3V pin
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Open the primary endpoint’s 0-1 jumper to prevent the Air Sensor from receiving 5V
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Open the VCC1 & GND jumpers on both endpoints so that the 5V doesn’t needlessly flow back towards the midpoint. I think I’m too old to still use the water analogy.
Option 2:
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Use an inline RJ45 diagnostic breakout near the midpoint
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Access VCC1 from the breakout and inject 5V there, bam done! right? maybe?
Does either of these approaches make sense, or is there a better way to distribute 5V from only the midpoint in this setup?
Thanks in advance for any guidance!
Best,
Woogly