Grove ↔ STEMMA (classic) compatibility
Connecting Grove and STEMMA (classic) — and the reverse, STEMMA (classic) to Grove. Here's the verdict, the exact part, and the voltage catch.
Grove and STEMMA (classic) use different connectors (Grove 4-pin vs JST-PH) with no common off-the-shelf cable — bridge them with an adapter, or route both through the JST-SH (Qwiic/STEMMA QT) ecosystem.
Side by side
| Spec | Grove | STEMMA (classic) |
|---|---|---|
| Connector | Grove 4-pin | JST-PH |
| Pitch | 2 mm | 2 mm |
| Logic | varies | 3v3-5v |
Why this verdict
What actually decides Grove ↔ STEMMA (classic)
The connector. Grove uses a Grove 4-pin at 2 mm; STEMMA (classic) uses a JST-PH at 2 mm. Different housings and different pitch mean no cable mates them directly — an adapter is doing real work, not just convenience.
The pin order. Grove runs SCL → SDA → VCC → GND while STEMMA (classic) runs SCL → SDA → V+ → GND. A plug that fits mechanically but disagrees on order is the worst case: it looks right and the bus stays silent, or worse, power meets a data line. Use an adapter made for this pair — see the pinout visualizer to see the two side by side.
The voltage. Grove is varies; STEMMA (classic) is 3.3–5 V tolerant. i2c has no negotiation — whatever the host drives lands on every device. If one side is 3.3 V-only and your host is 5 V, a level shifter isn't optional, it's the difference between a working bus and a dead sensor. The compatibility checker surfaces this for any combination.
Bridged, it's still one ordinary i2c bus: unique addresses per device (conflicts have fixes), pull-ups in parallel, and a 400 pF capacitance budget. Nothing answering after you connect? Run an i2c scan — it separates a cable problem from an address problem in seconds.
Questions
Grove & STEMMA (classic) FAQ
Can you connect Grove to STEMMA (classic) directly?
Not directly — Grove (Grove 4-pin) and STEMMA (classic) (JST-PH) use different connectors, so you need an adapter. Grove and STEMMA (classic) use different connectors (Grove 4-pin vs JST-PH) with no common off-the-shelf cable — bridge them with an adapter, or route both through the JST-SH (Qwiic/STEMMA QT) ecosystem.
Do I need a level shifter between Grove and STEMMA (classic)?
Only if the logic voltages differ — typically a 5 V host with a 3.3 V-only device. Grove is varies; STEMMA (classic) is 3v3-5v. If both ends run at 3.3 V, no level shifter is needed.
Is the Grove pinout the same as STEMMA (classic)?
No. Grove is wired SCL / SDA / VCC / GND and STEMMA (classic) is SCL / SDA / V+ / GND. That difference is exactly why you can't just force a plug that seems to fit — an adapter built for this pairing re-orders the conductors for you.
Can I chain Grove and STEMMA (classic) devices on one bus?
Physically yes, once the connectors are bridged — electrically it's still one i2c bus, so the usual rules decide it. Every device needs a unique address, all the pull-up resistors sit in parallel, and total cable capacitance has a 400 pF ceiling. Mixing ecosystems doesn't change the bus; it just changes the plug.
Related pairings
Other Grove and STEMMA (classic) combinations
Every pairing is pre-answered — here are the rest involving either of these two. The verdict on each tile is the cautious one, since it assumes nothing about your host's voltage.
Or start from a standard: Grove and STEMMA (classic) each list their pinout and every ecosystem they reach. The full pairing index has all 15, and the compatibility checker does it interactively.