SparkFun QwiicBus - MidPoint

The SparkFun QwiicBus MidPoint works in tandem with the QwiicBus Endpoint so you can extend the range of your I2C bus and easily tap into it to drop in devices wherever you would like. The QwiicBus uses NXP’s PCA9615 IC, which converts the two default I2C signals into four differential signals, two for SCL and two for SDA. The differential signals sent over Ethernet cables from the EndPoint connect to the breakout through the on-board RJ-45 connectors. The differential signaling allows the I2C signals to reach distances of up to 100ft. while still maintaining their signal integrity! To make it even easier to get your readings, all communication is enacted exclusively via I2C, utilizing our handy Qwiic system so no soldering is required to connect it to the rest of your system. However, we still have broken out 0.1"-spaced pins in case you prefer to use a breadboard.

The simplicity of the PCA9615 used on the QwiicBus boards is one of its biggest appeals. Other I2C communication methods require packetizing I2C communication into another protocol, be it RS-485 or 1-Wire. However, the PCA9615 keeps the I2C protocol by utilizing a differential transceiver.

The MidPoint also features a LMR33630 buck regulator users can enable to source larger amounts of current (up to 3A@3.3V) to devices attached to the MidPoint.

The SparkFun Qwiic Connect System is an ecosystem of I2C sensors, actuators, shields and cables that make prototyping faster and less prone to error. All Qwiic-enabled boards use a common 1mm pitch, 4-pin JST connector. This reduces the amount of required PCB space, and polarized connections mean you can’t hook it up wrong.

  • Uses the PCA9615 Buffer IC
  • Includes the LMR33630 buck regulator for high-power applications
  • I2C Supply voltage range 2.3-5.5V
  • Differential Supply voltage range 3-5.5V
  • Buck Regulator Supply Voltage Range: 3.6-36V
  • Multiple power configurations depending on application needs
  • 2x Qwiic Connectors
  • 2x RJ45 Connectors

SparkFun QwiicBus - MidPoint Product Help and Resources

SparkFun QwiicBus Hookup Guide

April 1, 2021

Build a long-range, noise-isolated I2C bus with the SparkFun QwiicBus Kit featuring the QwiicBus EndPoint and MidPoint following this Hookup Guide.

Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

2 Electrical Prototyping

Skill Level: Rookie - You may be required to know a bit more about the component, such as orientation, or how to hook it up, in addition to power requirements. You will need to understand polarized components.
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Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • tulgee / about 5 months ago / 1

    It would be nice to see this redone with the ethernet jacks rotated 90 degrees. It would be a whole lot easier to protect your project in a box if you could make one hole in one side rather than try to figure out how to make this weird design work.

  • Member #1668110 / about 3 years ago / 1

    Can this "midpoint" be directly connected to the Raspberry Pi and used as a t-connector? What I need is to 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.

Customer Reviews

5 out of 5

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Great addition to the differential I2C setup.

This was the one piece missing in the Sparkfun lineup of differential I2C stuff -- now its complete! I'm using this in my home with thermometers/humidity sensors. I have a total run of 200 ft of differential I2C and it works perfectly. I did wrap a common mode choke using the last 25 ft of ethernet cable as it enters the enclosure containing the computer. I was worried about the long antenna nature of the wires for ~MHz interference. I don't know if this has helped the reliability -- so far it has worked perfectly. I have not yet had a chance to use the new setup for power, including access to the 4th twisted pair. I'm looking forward to running 48V down that pair for higher powered peripherals in the future.