# Adafruit Pi Stemma QT Breakout ## Overview ![breakout on a pi with a stemma board](https://cdn-learn.adafruit.com/assets/assets/000/138/317/medium800/adafruit_products_6365-04.jpg?1752154698 ) The **Adafruit Pi Stemma** is a small, easily removable breakout that easily adds a 4-pin JST SH pin (Stemma QT or [Qwiic](https://www.adafruit.com/?q=qwiic)) connector to your Raspberry Pi. The 2x3 socket design allows you to plug securely into the Pi's I2C bus with no soldering required. It works great if you want to add a [QT connector](https://www.adafruit.com/?q=jst%20sh%204-pin%20connector%20pack%20qwiic) for quick I2C sensor and devices integration without any header-fiddling and no soldering. ![front view of the board](https://cdn-learn.adafruit.com/assets/assets/000/138/318/medium800/adafruit_products_6365-03.jpg?1752154755 ) Pi Stemma has a 2x3 header on top that connects to the power and I2C pins, simply line up with the edge of the 2x20 connector on your Pi or Pi Compatible. It has a single JST SH connector that connects to your Pi's I2C bus (SDA, SCL, 3V, and Ground). It also features a 3.3V regulator, allowing it to work with all Qwiic or Stemma QT devices without risking a brownout dip. A green LED lets you know it's powered correctly. We also added two 10K pullup resistors since there are some Pi compatible boards that don't have them included. ![back view of the board](https://cdn-learn.adafruit.com/assets/assets/000/138/319/medium800/adafruit_products_6365-01.jpg?1752154793 ) You can use it with any Linux single board computer or microcontroller that has '2x20 Pi-compatible pinout' (there are a lot!) and then [check out Blinka, our Python interface library,](https://circuitpython.org/blinka) so [you can use our huge collection of CircuitPython libraries on SBC computers using Python](https://circuitpython.readthedocs.io/projects/bundle/en/latest/)! [Check out all our STEMMA QT offerings here, including a wide range of lengths and connectors](https://www.adafruit.com/category/1005) ![stemma qt view of the board](https://cdn-learn.adafruit.com/assets/assets/000/138/320/medium800/adafruit_products_6365-02.jpg?1752154829 ) # Adafruit Pi Stemma QT Breakout ## Pinouts ![front and back view of the breakout](https://cdn-learn.adafruit.com/assets/assets/000/138/327/medium800/adafruit_products_double.jpg?1752157541 ) ## 2x3 Header At the top edge of the breakout is a 2x3 header that connects to the power and I2C pins on your Raspberry Pi or Pi Compatible. Line up with the edge of your chosen single board computer 2x20 GPIO connector to plug it in. ## STEMMA QT Connector - **[STEMMA QT](https://learn.adafruit.com/introducing-adafruit-stemma-qt) -** This connector, on the bottom edge of the breakout, allows you to connect to sensors and breakout boards with STEMMA QT / Qwiic connectors. - **SDA/SCL** - The I2C pins for the STEMMA QT connector are connected to the default **I2C** port on the Pi (GPIO 2 and 3). - **3.3V/GND** - The power for the STEMMA QT connector is 3.3V. Ground is the common ground for power and logic. ## Power LED and Jumper - **Power LED -** To the left of the STEMMA QT port along the bottom edge of the board is the power LED. It is a green LED. - **LED jumper ** - This jumper is located on the back of the board and is outlined in white on the board silk. Cut the trace on this jumper to cut power to the power LED. # Adafruit Pi Stemma QT Breakout ## I2C Scan - Terminal To do an I2C scan on a Raspberry Pi the `i2cdetect` command is used. If not already done, be sure to enable I2C on the Raspberry Pi via `raspi-config`. If the `i2cdetect` command is not found, install it with: ```auto sudo apt-get install i2c-tools ``` And then to run a scan, use `i2cdetect` with the following command line parameters: ```auto i2cdetect -y 1 ``` On modern Raspberry Pi OS releases, you do **not** need to run the command with `sudo`. The `-y` disables interactive mode, so it just goes ahead and scans. The `1` specifies the I2C bus. ## Normal Behavior If all goes well, you should get a list of addresses for each device found. In the example below, an [Adafruit BMP280 breakout](https://www.adafruit.com/product/2651) is attached to a Raspberry Pi 4. ![](https://cdn-learn.adafruit.com/assets/assets/000/104/693/medium800/sensors_Screenshot_from_2021-09-16_10-55-46.png?1631814965) The BMP280's I2C address of `0x77` shows up as expected. ## Missing Device or Pull Ups If the device is disconnect and/or the pull up resistors are missing, the results will look like this: ![](https://cdn-learn.adafruit.com/assets/assets/000/104/695/medium800/sensors_Screenshot_from_2021-09-16_11-05-56.png?1631815818) The scan runs fine, but no addresses are shown. Keep in mind that Raspberry Pi's include pull up resistors on the SCL and SDA pins. # Adafruit Pi Stemma QT Breakout ## I2C Scan - Python with Blinka It's easy to use the **Pi Stemma QT Breakout** with Python and Blinka. To demo the I2C functionality, you can run an I2C scan with one of many STEMMA QT / Qwiic compatible boards like the AHT20 STEMMA QT breakout below. You can use this breakout with a computer that has GPIO and Python [thanks to Adafruit\_Blinka, our CircuitPython-for-Python compatibility library](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux). ### Adafruit AHT20 - Temperature & Humidity Sensor Breakout Board [Adafruit AHT20 - Temperature & Humidity Sensor Breakout Board](https://www.adafruit.com/product/4566) The AHT20 is a nice but inexpensive temperature and humidity sensor [from the same folks that brought us the DHT22](https://www.adafruit.com/product/385). You can take sensor readings as often as you like, and it uses standard I2C so its super easy to use with any Arduino or... In Stock [Buy Now](https://www.adafruit.com/product/4566) [Related Guides to the Product](https://learn.adafruit.com/products/4566/guides) ![Angled Shot of the Adafruit AHT20 Temp+Hum Sensor - Assembled PCB](https://cdn-shop.adafruit.com/640x480/4566-04.jpg) ## Python Computer Wiring Since there are _dozens_ of Linux computers/boards you can use, we will show wiring for Raspberry Pi. For other platforms, [please visit the guide for CircuitPython on Linux to see whether your platform is supported](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux). Here's the Raspberry Pi wired with the Pi Stemma QT Breakout and an AHT20 breakout: Plug the Pi Stemma QT Breakout header into the Raspberry Pi GPIO. Then, plug the AHT20 sensor into the breakout with a STEMMA QT cable. No soldering required, making it quick and easy. ![raspberry pi fritzing with pi stemma](https://cdn-learn.adafruit.com/assets/assets/000/138/418/medium640/adafruit_products_pi_bb_bb.jpg?1752588264) ## Python Usage Once you have the library `pip3` installed on your computer, copy or download the following example to your computer, and run the following, replacing **code.py** with whatever you named the file: `python3 code.py` ## Example Code The console output will appear wherever you are running Python. https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/I2C_Scanners/circuitpython/code.py First, the I2C bus is found. Then, in the loop, the connected I2C device addresses are printed to the console. The AHT20 is on address **0x38**. If you have that breakout connected, then you should see that address printed repeatedly.  If you have a different breakout, a different address specific to that board would typically be printed. ![serial console for the i2c scan](https://cdn-learn.adafruit.com/assets/assets/000/138/417/medium800/adafruit_products_20250715_09h50m03s_grim.jpg?1752588043 ) # Adafruit Pi Stemma QT Breakout ## Downloads ## Files - [EagleCAD PCB files on GitHub](https://github.com/adafruit/Adafruit-Pi-Stemma-QT-Breakout-PCB) - [3D models on GitHub](https://github.com/adafruit/Adafruit_CAD_Parts/tree/main/6365%20Pi%20STEMMA%20QT%20Breakout) - [Fritzing object in the Adafruit Fritzing Library](https://github.com/adafruit/Fritzing-Library/blob/master/parts/Adafruit%20Pi%20Stemma%20QT%20Breakout.fzpz) ## Schematic and Fab Print ![schematic](https://cdn-learn.adafruit.com/assets/assets/000/138/321/medium800/adafruit_products_schem.png?1752155312 ) ![fab print for the pcb](https://cdn-learn.adafruit.com/assets/assets/000/138/322/medium800/adafruit_products_fab.jpg?1752155488 dimensions are in inches) ![](https://cdn-learn.adafruit.com/assets/assets/000/138/331/medium800/adafruit_products_6365_Pi_STEMMA_QT_Breakout.jpg?1752171750 ) ## Primary Products ### Adafruit Pi Stemma QT Breakout for Raspberry Pi and Compatibles [Adafruit Pi Stemma QT Breakout for Raspberry Pi and Compatibles](https://www.adafruit.com/product/6365) The **Adafruit Pi Stemma** is a small, easily removable breakout that easily adds a 4-pin JST SH pin (Stemma QT or [Qwiic](https://www.adafruit.com/?q=qwiic)) connector to your Raspberry Pi. The 2x3 socket design allows you to plug securely into the Pi's I2C bus... Out of Stock [Buy Now](https://www.adafruit.com/product/6365) [Related Guides to the Product](https://learn.adafruit.com/products/6365/guides) ## Featured Products ### STEMMA QT / Qwiic JST SH 4-Pin Cable - 50mm Long [STEMMA QT / Qwiic JST SH 4-Pin Cable - 50mm Long](https://www.adafruit.com/product/4399) This 4-wire cable is 50mm / 1.9" long and fitted with JST SH female 4-pin connectors on both ends. Compared with the chunkier JST PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert and remove. Out of Stock [Buy Now](https://www.adafruit.com/product/4399) [Related Guides to the Product](https://learn.adafruit.com/products/4399/guides) ### STEMMA QT / Qwiic JST SH 4-pin Cable - 100mm Long [STEMMA QT / Qwiic JST SH 4-pin Cable - 100mm Long](https://www.adafruit.com/product/4210) This 4-wire cable is a little over 100mm / 4" long and fitted with JST-SH female 4-pin connectors on both ends. Compared with the chunkier JST-PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert and remove. Out of Stock [Buy Now](https://www.adafruit.com/product/4210) [Related Guides to the Product](https://learn.adafruit.com/products/4210/guides) ### STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable [STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable](https://www.adafruit.com/product/4209) This 4-wire cable is a little over 150mm / 6" long and fitted with JST-SH female 4-pin connectors on one end and premium Dupont male headers on the other. Compared with the chunkier JST-PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert... Out of Stock [Buy Now](https://www.adafruit.com/product/4209) [Related Guides to the Product](https://learn.adafruit.com/products/4209/guides) ### STEMMA QT / Qwiic JST SH 4-pin Cable with Premium Female Sockets [STEMMA QT / Qwiic JST SH 4-pin Cable with Premium Female Sockets](https://www.adafruit.com/product/4397) This 4-wire cable is a little over 150mm / 6" long and fitted with JST-SH female 4-pin connectors on one end and premium female headers on the other. Compared with the chunkier JST-PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert and... In Stock [Buy Now](https://www.adafruit.com/product/4397) [Related Guides to the Product](https://learn.adafruit.com/products/4397/guides) ### JST SH 4-pin Cable with Alligator Clips - STEMMA QT / Qwiic [JST SH 4-pin Cable with Alligator Clips - STEMMA QT / Qwiic](https://www.adafruit.com/product/4398) This cable will make it super easy to use our plug-and-play STEMMA QT boards with boards like Circuit Playground. On one end you get a Qwiic / STEMMA QT connector (technically known as a JST SH 4-pin plug)  into 4 individual wires with grippy alligator clips. We're carrying these to... Out of Stock [Buy Now](https://www.adafruit.com/product/4398) [Related Guides to the Product](https://learn.adafruit.com/products/4398/guides) ## Related Guides - [Interpreting Environmental Sensor Data With Local "Edge" LLMs](https://learn.adafruit.com/interpreting-environmental-sensor-data-with-llms.md) - [Adafruit SEN6x Breakout](https://learn.adafruit.com/adafruit-sen6x-breakout.md) - [AdaBox 006](https://learn.adafruit.com/adabox006.md) - [Using IFTTT with Adafruit IO to Make an IoT Door Detector](https://learn.adafruit.com/using-ifttt-with-adafruit-io.md) - [Adafruit Circuit Playground Bluefruit](https://learn.adafruit.com/adafruit-circuit-playground-bluefruit.md) - [Read-Only Raspberry Pi](https://learn.adafruit.com/read-only-raspberry-pi.md) - [Microsoft Azure Cost Monitor](https://learn.adafruit.com/azure-cost-monitor.md) - [Sparky the Blue Smoke Monster Automaton](https://learn.adafruit.com/sparky-automaton.md) - [Matrix Portal RGB Display Handbag](https://learn.adafruit.com/matrix-portal-rgb-display-handbag.md) - [Adafruit MOSFET Driver](https://learn.adafruit.com/adafruit-mosfet-driver.md) - [A Logger for CircuitPython](https://learn.adafruit.com/a-logger-for-circuitpython.md) - [Customizing USB Devices in CircuitPython](https://learn.adafruit.com/customizing-usb-devices-in-circuitpython.md) - [Adafruit ANO Rotary Encoder to I2C Adapter](https://learn.adafruit.com/adafruit-ano-rotary-navigation-encoder-to-i2c-stemma-qt-adapter.md) - [Mu Keyboard Shortcut Cheat Sheets](https://learn.adafruit.com/mu-keyboard-shortcut-cheat-sheets.md) - [MIDI Breath Controller](https://learn.adafruit.com/midi-breath-controller.md)