Lamprey Encoder Calibration Problem

We are using the lamprey encoder for our custom swerve modules. We had problems performing a basic calibration. We powered up the encoder while holding the blue button, and the encoder entered the calibration sequence (LEDs blinked as they should, also we got an output in UART that stated that calibration started). Then we rotated the magnet slowly (3 times and even more, as manual requires) yet the status lights do not brighten accordingly. From that point the calibration does not complete after many rotations, and it is stuck in the basic calibration mode.

We also are using direct analog input straight to the roboRIO, giving the encoder vcc from it as well.

Do you have any suggestions as to how to fix this problem or what causes it?

I couldn’t get it to work either, but my button was super-hard to access. So, it may be user error :wink: Say, could you take a peek at the PWM output and tell me what it looks like over a 10-15 second span with the swerve not moving?

Solution:
We talked to the people at 221 robotic systems which provide this product and reached the conclusion that the lamprey pcb was too far away from the magnet ring, which concluded in faulty readings.

Although we placed the magnet at a distance well within the range specified in the manual (0.15" away) the signal was not strong enough and after talking to the manufacturer they said the magnet should not be father than 0.09" away.

Perhaps the people at lamprey should fix the manual to avoid future mishaps like this one.

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I had the same problem. Initially designed at .15". Had to go to .085 to .9 to get 3 lights. Also at first the top of the neo pinion was even with the bottom of the magnet. Moved the magnet and encoder up .4" and the magnetic interference went away. Be careful when calibrating that you do a quick firm button press or it will mess up. We printed out a 36 point calibration circle and tape it to the bottom. If you suffer enough and get a good calibration these seem to work. They have to work because our new swerve design relies on them. We use analog out and so far they are accurate.

I addressed this concern via email but I will add my response here as well…

Under ideal lab conditions we were able to successfully calibrate sensors with up to 0.500” of air gap…

However, the larger the gap the less usable sensor data you get and your overall resolution decreases.

We did not state this very accurately in our documentation…we will update.

In general you want to magnet as close as possible so you get access to the full strength/range of the target data.

Also, using the UART interface while calibrating is really helpful and gives you insight into the measurements.

The newest updated version of these sensor has USB which makes this step much simpler. Coming soon.

Question. When will these be available? We are about to order a bunch from AndyMark. Would prefer USB but can’t wait long.

They’re 4 weeks away unfortunately…

Shoot us a PM and we can keep you posted.

When the updated version arrives we will consider special pricing for anyone who wants to upgrade.

The new sensor is also 12-but which is a nice upgrade.