SPI is not very different from I2C. To enable a slave device, we need to pull the CS pin low and after our read or write is complete, just pull the pin high again. This will disable the slave device.
Set the TAP THRESHOLD to 2.5g. To do that we need to write 40 (2.5/.0625) to the THRESH_TAP Register. This means that you need at least 2.5g acceleration in Z AXIS in order for the tap to qualify as TAP.
The ADXL345 is a complete 3-axis acceleration measurement system with a selectable measurement range of ±2 g, ±4 g, ±8 g, or ±16 g. It measures both dynamic acceleration resulting from motion or shock and static acceleration, such as gravity, which allows the device to be used as a tilt sensor. In this tutorial we are going to interface ADXL345 with STM32.