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zephyr-cp: add board.STEMMA_I2C - #11640
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A stemma-qt-connector node (upstream's binding, also used for Qwiic connectors) marks a board's STEMMA QT connector. It adds no pin names. - Boards that route buses with iobroker: the connector's pins decide. With the same pins as board.I2C(), STEMMA_I2C is the same object; with other pins, it is a second board I2C bus, as on the QT Py boards in the other ports. - All-static boards: STEMMA_I2C is the instance labeled zephyr_i2c, Zephyr's label for the bus wired to such connectors, and the same object as board.I2C() when it is the same instance. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Add a stemma-qt-connector node on SCL/SDA, so board.STEMMA_I2C is board.I2C(), as in ports/nordic. The upstream board has no node for the connector. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Oct 20, 2026
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Let's minimize how much we special case this. Please merge in the other commit too. I think it's diff is still showing for me.
Instead of a special case for stemma-qt-connector nodes, give the connector a CONNECTORS entry that names its pins STEMMA_SCL and STEMMA_SDA, and find board.STEMMA_I2C's pins by those names, like board.I2C()'s SCL and SDA. Qwiic connectors use the same binding, so they get the same names. A pin prints as its first board name, so list the STEMMA names last: board.SCL still prints as board.SCL. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Note by @dhalbert. Written with Claude.
This PR was stacked on #11638, which has now merged. It needs #11638 for
board.I2C()on the Feather RP2040.Provide a mechanism for
board.STEMMA_I2Con both boards where it is shared withboard.I2C()and on other boards where it has its own pins. Motivated by Zephyr CLUE needingboard.STEMMA_I2C. On that board, it shares pins withboard.I2C().Upstream Zephyr already marks STEMMA QT connectors with a
stemma-qt-connectornode, on about 26 boards. Qwiic connectors use the same binding. Zephyr also labels the bus wired to such a connectorzephyr_i2c.stemma-qt-connectorentry inCONNECTORSnames the connector's pinsSTEMMA_SCLandSTEMMA_SDA, andSTEMMA_I2Cuses those pins. So with the same pins asboard.I2C(),STEMMA_I2Cis the same object; with other pins, it is a second board I2C bus.STEMMA_I2Cis the instance labeledzephyr_i2c, and the same object asboard.I2C()when it is the same instance.board.SCLstill prints asboard.SCL, notboard.STEMMA_SCL.board.overlay, on SCL/SDA.Testing
board.STEMMA_I2C()isboard.I2C(); scan finds the onboard sensors.STEMMA_I2Cis a second bus, usable at the same time asboard.I2C()(tested before the switch to pin names; the bus layout code didn't change).stemma_connectorandzephyr_i2c: &i2c1):board.STEMMA_I2C()isboard.I2C().board.STEMMA_SCLandboard.STEMMA_SDAareboard.SCLandboard.SDA, and all four print asboard.SCL/board.SDA.