ADXL345_WE

Linux library for the ADXL345 accelerometer, using spidev.

Forked from ADXL345_WE by Wolfgang (Wolle) Ewald

The changes vs the original:

• only one constructor now, taking path to the device:

  ADXL345_WE myAcc = ADXL345_WE("/dev/spidev1.1");

• all SPI functions switched to talk over spidev respectively

• converted to regular C++ from Arduino flavor (albeit retaining a bunch of Arduinisms, for example I typedef'd bool boolean, String std::string)

• Only one simple example is left. I don't have time or patience to convert the rest from Arduino sketches. Go to original repository to get them and edit to work (compare original's ADXL345_SPI_basic_data.ino with mine hADXL345_SPI_basic_data.cpp to see what needs to be done. Generally mainly switch the constructor, attach a trivial main(), switch output from Serial to console, adjust types if needed.

No changes vs the original:

• there's still a bunch of dead code regarding pins, Arduino's SPI, and original's support for I2C which is now hardcoded to be always off.
• I didn't touch what I didn't understand. Or need, in particular, so if the result is that some functions are broken or unavailable, sorry!

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This project was born from urgent need to debug ADXL345 connected to Octoprint+Klipper; it's served its purpose for me and I don't plan to develop or maintain it any longer. Also, don't expect any support regarding spidev or ADXL345, I'm not knowledgeable with them to any degree. Also, don't submit any issues, bugs, bugfixes, feature requests, features, or anything. If you can fix it yourself, just fork it and fix. If you can't - sorry, provided as-is. Find someone else to do it, not me.

Original author's message

I have tried to create a library for the ADXL345 which is easy to use for people who don't want to deal with all the registers. Therefore I have added lots example sketches which will enable you to deal even with the more complex features such as the FIFO modes. Howerever I still recommend to have a look into the data sheet to get a deeper understanding.

You can use both I2C and SPI. If you want to find out how to use SPI, look at the ADXL345_SPI_basic_data.ino.

A detailed tutorial is available:

https://wolles-elektronikkiste.de/adxl345-teil-1 (German)

https://wolles-elektronikkiste.de/en/adxl345-the-universal-accelerometer-part-1 (English)

If you are not so much experienced with the ADXL345, I recommend to work through the examples in the following order:

1. ADXL345_basic_data
2. ADXL345_SPI_basic_data
3. ADXL345_calibration
4. ADXL345_angles_orientation
5. ADXL345_pitch_roll_corrected_angles
6. ADXL345_sleep
7. ADXL345_free_fall_interrupt
8. ADXL345_data_ready_interrupt
9. ADXL345_activity_inactivity_interrupt
10. ADXL345_auto_sleep.ino
11. ADXL345_single_tap
12. ADXL345_double_tap
13. ADXL345_fifo_fifo
14. ADXL345_fifo_stream
15. ADXL345_fifo_trigger

To develop this library I have worked with a ADXL345 module. It should also work with the bare ADXL345 IC. For the module I have noticed that the power consumption is much higher than mentioned in the data sheet. I think the issue is the voltage converter on the module. You can reduce the power consumption by choosing 3.3 volts instead of 5 volts. At least this worked with my module.

If you like my library please give it a star. If you don't like it I would be happy to get feedback. And if you find bugs I will try to eliminate them as quickly as possible.

If SPI does not work

My library has implemented SPI 4-Wire. Some modules have SDO connected GND via an 0 ohm resistor. With this resistor only SPI 3-Wire would work. Your options are:

1. Remove the 0 ohm resistor connected to SDO (R4 on my module)
2. Replace the 0 ohm resistor connected to SDO by an internal or external pull-down resistor of 4.7 kohm or 10 kohm
3. Find another library which supports SPI 3-Wire