In the upper left hand corner of the board you can see the GPIO header. Below that is the P5 header footprint, a 2×4 series of vias. You won’t see the P5 label until you flip the board over.
Now, there are some folks that will tell you the only way to get to the second I2C bus is to access the camera S5 header (or the S2 header). That would involve some incredible soldering work, or a socket. I don’t have the socket, and my hands aren’t good enough to solder at that pitch.
However, I can solder that P5 header. The unfortunate thing is that the P5 header is really close to the GPIO header. Using the P5 header while using Lady Ada’s Pi Cobbler header may be problematic. I took some long headers and soldered them in place, at a slight angle….
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