This is a DS2482S-800 Stemma QT board that uses a I2C-to-1W controller chip, with 8 selectable channels, built-in parasitic-power-pullups, adjustable I2C address and a wide operating voltage range! You can easily connect it to an existing I2C bus and then use the breakout pads to attach multiple DS18B20’s, or pair it with our 1-Wire chaining breakouts for fancier experimentation.
You’re probably familiar with the ‘top three’ electronics protocols: I2C, SPI and UART. Perhaps you’re aware of a fourth one, called “1-Wire” which was invented by Dallas Semiconductor (which became Maxim, which became Analog Devices). As you may expect, this protocol uses a single data wire plus a ground wire (and an optional power wire) to connect to any number of sensors or memory chips that all share the same bus.
In theory, there’s a lot of different 1-Wire devices out there, but in reality almost everyone uses 1-Wire for DS18B20 temperature sensors. the long wire lengths and ease of ‘chaining’ by sharing a single bus wire makes it perfectly fine for this purpose. You can bit-bang 1-Wire on most microcontrollers, and some SBCs like Raspberry Pi have kernel module support. But are lots of chips or firmware stacks without 1-Wire capability, or maybe you want to use 1-Wire devices on your desktop computer or other SBC with I2C.
You might be wondering: if you can connect multiple 1-Wire devices on a single wire, then why have 8 channels on this breakout? Reason is: if you have 8 temperature sensors, there’s no easy way to know which one is which other than connecting them one at a time and reading the unique ROM identifier. With this breakout you can select the channel so you know for sure which location is being measured, even if the sensor is swapped out later.
To get you going fast, we spun up a custom-made PCB in theSTEMMA QT form factor, making it easy to interface. The STEMMA QT connectors on either side are compatible with the SparkFun Qwiic I2C connectors. This allows you to make solderless connections between your development board and the DS2482S-800 or to chain it with a wide range of other sensors and accessories using a compatible cable. You can power the board directly from the STEMMA QT cable, whether 3V or 5V, that voltage will also be the power output for the 1-Wire peripherals.
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