i2c connector pinout visualizer
Switch between standards and hover any pin to see its role — SDA, SCL, power, ground and the interrupt line where a standard has one.
JST-SH · 4-pin · 1 mm pitch · 3v3
Why pin order matters
Why i2c pinout order matters: a plug that fits can still be wrong
The failure this tool exists to prevent: two connectors that mate mechanically but disagree about which conductor carries which signal. i2c gives you no warning — there's no handshake, no negotiation, no error. Best case SDA lands on SCL and the bus just goes quiet, so you spend an evening blaming the sensor. Worst case a power pin meets a data line and something stops working permanently.
This is why Qwiic and STEMMA QT interchange freely — not because both use a 4-pin JST-SH, but because both wire it GND → 3V3 → SDA → SCL in that order. Same plug, same order, so cables cross over with nothing in between. Other ecosystems chose differently, and an adapter for those pairs is physically re-ordering conductors, not just changing the housing.
Two things this diagram deliberately doesn't tell you: the voltage each standard expects (a 3.3 V-only chain on a 5 V host needs a level shifter regardless of pinout), and whether a given pairing needs an adapter at all — that's the compatibility checker, or the pre-answered pairing pages.
Go deeper
Each standard has its own reference page with a static pinout, full specs and compatibility — browse the connector standards. If you're starting a project rather than debugging one, which connector? narrows it down in two questions, and what is i2c covers the bus itself.