Trouble interfacing ADXL345/375 accelerometer

[AvionicsMaster1]

Are you using internal oscillator?

[achilles03]

It's using an external crystal with the "HS" oscillator setting.

After adding some caps, the output is much better and it's clearly exporting acceleration data correctly. Flipping it around on all axes show the expected +/-1g change. The offsets are rather large (+3g in some axis), but that can be adjusted/calibrated.