avsa242 / lis3dh-spin

Parallax P8X32A/Propeller, P2X8C4M64P/Propeller 2 driver object for the ST LIS3DH 3DoF Accelerometer

lis3dh-spin

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This is a P8X32A/Propeller, P2X8C4M64P/Propeller 2 driver object for the ST LIS3DH 3DoF accelerometer

IMPORTANT: This software is meant to be used with the spin-standard-library (P8X32A) or p2-spin-standard-library (P2X8C4M64P). Please install the applicable library first before attempting to use this code, otherwise you will be missing several files required to build the project.

Salient Features

• I2C connection at up to 400kHz (P1, P2)
• SPI connection (3w, 4w) at ~4MHz (P1), up to 5MHz (P2)
• Read raw or scaled accelerometer data output
• Set output data rate
• Set full-scale range
• Enable per-axis output
• Flags to indicate data is ready, or has overrun
• Set calibration offsets
• FIFO control and flag reading (empty, full, number of unread samples)
• Set interrupt sources by mask, set threshold level, read interrupt flags
• Single and double-click detection
• Free-fall detection

Requirements

P1/SPIN1:

• spin-standard-library
• 1 extra core/cog for the PASM I2C or SPI engine (none, if bytecode engine is used)
• sensor.accel.common.spinh (provided by spin-standard-library)

P2/SPIN2:

• p2-spin-standard-library
• sensor.accel.common.spin2h (provided by p2-spin-standard-library)

Compiler Compatibility

Processor	Language	Compiler	Backend	Status
P1	SPIN1	FlexSpin (6.9.4)	Bytecode	OK
P1	SPIN1	FlexSpin (6.9.4)	Native/PASM	OK
P2	SPIN2	FlexSpin (6.9.4)	NuCode	Some runtime issues
P2	SPIN2	FlexSpin (6.9.4)	Native/PASM2	OK

(other versions or toolchains not listed are not supported, and may or may not work)

Limitations

• TBD

lis3dh-spin's Issues

Add support for int2

Currently only the int1 pin is supported.

Add free-fall detection

The chip has the ability to detect free-falls and generate an interrupt.

P2/NuCode: Driver doesn't start when built for SPI mode

The P2/SPIN2 driver won't start in SPI mode when built with the NuCode backend even at slow speeds (~100kHz).
I2C is fine. PASM2 backend is fine.

Add 3-wire SPI support

Add support for 3-wire SPI connection (currently I2C and 4-wire SPI are supported)

Add support for on-chip temperature sensor

The chip has a temperature sensor on-die used for compensation for drift, but it can also be read by the user.

Calculate timestep and store in a global var

Currently, every method that needs it (clicklatency(), clicktime(), doubleclickwindow(), freefalltime(), int1duration()) duplicates the code to calculate it, and also calls acceldatarate() to do so, which adds unnecessary bus traffic.

Instead, calculate it ahead of time in acceldatarate() and store it in a global var that can just be read any time it's needed.

A note might also need to be added to affected methods that acceldatarate() must have been called once prior in order for them to work correctly. Either that or the variable will need to be set to the POR