MMA8451Q Accelerometer

The MMA8451Q is a three-axis accelerometer with 14-bit resolution, read over I2C. Tilt it in the simulator and firmware reads the new orientation from the same registers it would on real hardware.

Datasheet

The MMA8451Q datasheet documents the register map, the mode state machine, and the interrupt sources.

Pins

The breakout has a single 8-pin header. Names below are the silkscreen, left to right:

Pin	Simulator name	Description
VIN	VDD	Supply
GND	GND	Ground
3Vo	VDDIO	I/O rail
I2	INT2	Interrupt 2
I1	INT1	Interrupt 1
SCL	SCL	I2C clock
SDA	SDA	I2C data
A	SA0	Address select

SA0 chooses the I2C address: 0x1C when low, 0x1D when high. Leave it unwired to take the default.

Behaviour

Feature	Support	Notes
I2C register interface	✅
3-axis acceleration	✅	X, Y, Z in g
Mode state machine	✅	Standby / wake / sleep, gated the way the part gates it
Address select (SA0)	✅
Interrupt outputs	⚠️	Pins exist; interrupt sources are not driven
Orientation / tap / freefall detection	❌	Not modelled

• ✅ Fully supported ⚠️ Partial / stub ❌ Not supported

The part will not acknowledge on the bus until it is powered and has finished booting — the same gate real silicon applies, so firmware that probes too early sees the same NACK it would on a bench.

Controlling it

Drag the 3D control in the editor to tilt the sensor, and firmware reads the change immediately. From the SDK, the current reading is a sample channel:

run.stream("accel1").subscribe(({ value }) => {
  console.log(value); // { acceleration_x_g, acceleration_y_g, acceleration_z_g, mode }
});

Limitations

• INT1/INT2 are wirable but never asserted
• No tap, orientation, freefall or transient detection
• No FIFO