I need to know if the QwiicBus MidPoint board can be directly connected to the Raspberry Pi (via a Qwiic Shim) and used as a t-connector? What I need to do is use it as a “T-splitter” so I can send 2 cables with sensors in 2 different directions away from the Pi, and then use the QwiicBus EndPoints at the ends of both cables. Is it possible to use this board in this manner?
Thank you.
No; the midpoints/endpoints use signal differentials to compare data in the board itself - modifying them for this use will be extremely difficult
Hope this helps, happy sparking!
Well that’s useless! Why wouldn’t you design the MidPoint board to act as a true midpoint? What is the point of not being able to split the I2C buss in 2 directions? Scenario: I have a greenhouse, it’s 100 feet long, I need a sensor at each end of the greenhouse, the Pi is in the middle of the greenhouse where the door and the electrical boxes are. So to get a sensor at each end of the greenhouse, I would need to run 50 feet from the door to one end, and then run a cable all the way back 100 feet to the other end, for a total cable length of 150 feet, instead of just 2 runs of 50 feet? That’s just really poor design and a total lack of forethought 
So what products do you sell that would enable me to do what I need to do? I already have the 4-way Qwiic Hub, can I use that and split my cable in 2 directions using 4 of the endpoints?
I think I misunderstood your given scenario; after re-reading that should work as described. Check out the hookup guide here https://learn.sparkfun.com/tutorials/sp … 1615791300 for details about what can be accomplished with these.
You might give it a try and see if it works but you might need to play around with terminating resistors if you’re not following sparkfun’s guide.
TS-Russell:
I think I misunderstood your given scenario; after re-reading that should work as described. Check out the hookup guide here https://learn.sparkfun.com/tutorials/sp … 1615791300 for details about what can be accomplished with these.
I have read the hookup guide, twice, and it does not specifically show or mention the particular setup I need to achieve. Which is why I need to know if it can do what I need it to do before I spend $32 on the parts. It would be really helpful if your videos or the documentation would show the possible configurations with some simple wiring diagrams.
I asked an engineer and sadly you must put your controller on an end point and it has to do with how bus termination is done on the midpoint board. It’s possible in the future we might have a revision that lets you reconfigure the termination so that you can put your controller anywhere on the bus but for now you’re going to need to put an endpoint in the middle of your greenhouse, then run a cable down to a midpoint at one and and a second cable from the midpoint all the way to the other end of the greenhouse where you have another endpoint. It would look like the picture below.
Can I accomplish a split I2C bus by using the configuration in the attached diagram (using 4 EndPoints and a Qwiic MultiPort)? If so, would it be “plug and play” or would I need to modify anything on the EndPoint boards? If so please be specific as to what modifications would need to be made. (My sensors are already modified to have different I2C addresses.)
Haven’t tested that specific setup, but I believe that should work!
Thank you!
