Support

The USDA grant that funded the grower trials of the scarecrow ends in April 2024 and our ability to offer support will necessarily be reduced. Nevertheless, we are interested in your continued success in using these devices and would like to hear from you in case there's an easy fix. For questions about how to use the scarecrow to protect your crop, contact Dr. Rebecca Brown: brownreb@uri.edu. For more technical questions (mechanical, electrical), please contact David Brown: david_h_brown@uri.edu. 

Documentation for each model

The development of the 2024 model is still in process. Here are links to pages for the 2023 model, 2022 model, 2020 model, and 2018 model. 

Firmware updates

There are a few small but potentially useful updates to the behavior of the 2022 and 2023 scarecrow models that can be installed using a computer and a standard USB micro cable. Visit https://davidhbrown.github.io/laserscarecrow-firmware.

General troubleshooting

These notes are based primarily on the 2022 model/design but may have relevance to earlier models and to 2023 which mostly just changed the controls. You are welcome and encouraged to ask for further assistance or clarification. Please email David at david_h_brown@uri.edu 

Something broke

Please let us know (email to david_h_brown@uri.edu is good). We may be able to replace it or suggest a workaround.

The scarecrow is making all sorts of beeps and the laser only flashes briefly

This sounds like the self-test mode. Please take a look at section 7.3 in the 2022 Operation Manual or section 5 in the 2023 Operation manual to decide how best to configure the tape mode jumper for your deployment.

The scarecrow doesn't turn off at night or even if I cover the light sensor

In 2023 we have had several instances where the outer shrink tubing on the sensor pulled the light sensor leads so tightly together that they connected and tricked the scarecrow into perceiving full daylight. An in-the-field fix takes about 5 minutes with a small knife and a piece of electrical tape. Here's a video. We'd also be happy to send you a replacement light sensor.

Scarecrow has power but won't do anything

If the red LED on the circuit board is on but the scarecrow isn't moving or making any sound, check the LED on the the controls (inside the gray box) -- see section 7.2 in the Operation Manual. It should be off to start reliably. Press the blue push-button and make sure it is out (and the LED off when powered).

We saw one unit returned to us doing this where what was wrong was that the program stored in the microcontroller's flash memory had somehow changed (stray cosmic ray?) so it wouldn't boot. Reprogramming the microcontroller worked and is possible with free software but is technically a bit challenging. Let's talk if you think this might be happening to yours.

Laser rotates in only one direction, not randomly

This sounds like the settings mode is enabled; it will show you the maximum speed (and vertical sweep) currently set -- see section 7.2 in the Operation Manual. Check the controls inside the gray box. If the LED is on, the blue push-button is in ("on"). Press the blue push-button again so it pops out; this will save the settings and return to normal operation.

Scarecrow restarts unexpectedly or just stops

Generally, the scarecrow appears to restart when power is briefly lost and then is reconnected. If the restarts are more-or-less random, make sure the green plug is pushed all the way down into the socket on the board and ensure that your power supply is secure. Spring ("alligator") clips can be sensitive to vibration and a millisecond or two interruption in power is enough to restart the microcontroller. I much prefer power connections that screw down. 

If the restart happens at exactly the same point in the start-up sequence each time, it's possible that a flawed component is drawing too much power. (I saw this happen once with a laser module.) The question is which component. All of the laser module, stepper motor, servo, and tape sensor start up at about the same time in self-test mode (about 5 seconds after the pre-laser warning tone finishes) which makes diagnosis difficult. If you set the tape mode to ignore, the stepper will come on as part of the pre-laser warning and the tape sensor won't ever turn on. If you suspect the stepper motor, If you set the tape mode to any of the tape sensing modes, the stepper will come on first (to home), then the tape sensor will turn on for scanning. The laser and servo are enabled at the same time in any mode, so you'll probably need to pull their connectors back out of the rotating arm (see section 2.10 in the Assembly Guide) 

In 2023, we started seeing some units where it appears that a failed servo is causing this misbehavior. CAUTION: The laser may be on during this failure. This is easiest to observe in "ignore" mode -- jumper connecting the middle pins -- where the scarecrow stops after the pre-laser warning. The following video shows this. Notice how after the first pre-laser warning, the motor shudders to a stop and the power LED on the microcontroller flickers. The microcontroller did restart once, repeating the pre-laser warning, though the second time the LED did not flicker and it just stayed stuck. To verify this problem, disconnect the servo connector only (inside the rotating arm). If the scarecrow can then operate normally (except of course that the laser won't tilt up and down), the servo will need to be replaced. (Search for "Futaba S3107"... we may be able to provide a replacement during 2023 while the grant is still active.)

Laser module doesn't tilt up and down (servo issues)

⚠ Warning: you're going to be looking at the laser module while figuring this out, so please put the cap on it to block the laser emission.

If the scarecrow is set to one of its operating modes (using the tape mode jumper) It possible to set the controls so the servo won't move, so a good first check would be to enable the controls and slowly slide the middle slider up and down to see whether the servo/laser module tilt follows.

If it never worked, revisit step 2.10.5 in the Assembly Guide to check that the slip ring  cable is connected to the servo cable correctly: orange-to-white; red-to-red; brown-to-black. It is difficult but not impossible to reverse this. Check that the orange/red/brown pins from the slip ring cable are fully inserted into their housing and unbroken. Check the same color wires on the 8-position slip ring plug on the main circuit board. Contact us if you find broken wires (david_h_brown@uri.edu). 


Magnet sensor LED is always on

Most likely the magnet sensor has been damaged. It is susceptible to electrostatic discharge; a static electric shock you can feel would very probably damage it. Mechanically, you can check that the bare leads between the rectangular circuit board and the tiny sensor itself were not pushed together and shorted. If they are, try separating them (while power is off) with a thin tool. 

The 2024 model uses a surface-mount Hall-effect sensor on the magnet sensor, so no leads to bend.

Also check the magnet sensor cable (below)

Magnet sensor LED never comes on

The easiest fix would be if the magnet on the rotating arm is not correctly positioned. It should be as near the bucket wall as possible and at the top of the arm, at the same level as the black square component that extends from the magnet sensor. 

If the magnet has been lost, it definitely won't work! Contact us to see if we can send out a spare, but any decently strong rare-earth cylinder magnet 1/4" diameter by 1/2" long should work. Polarity does not matter.

Also check the magnet sensor cable, below.

I'm not sure how useful this would be, but you can use the stepper motor as a test magnet for the sensor. See picture to the right. You would need to separate the bucket top and bottom to remove the tape holding the sensor in position.

Check the magnet sensor cable

Disconnect the two ends of the magnet sensor cable and check that the color sequence of the wires in each end is the same. The tiny metal spring flaps that hold the wires in place should be visible through the slots. These should should resist a gentle tug on the wires.

If a wire pulls out without breaking, you may be able to use a thin knife blade to raise the flap and reinsert it. If one or more wires breaks, contact us for replacement or if you don't want to wait, the connectors are the standard "JST-XH" style easily found online (e.g., on our Amazon list).

You should be able to measure low resistance (continuity) between each metal end of the same color using a multimeter.

Bent leads (above) can cause malfunction. It may be possible to straighten them (below).

The stepper motor's magnet can trigger the magnet sensor, FWIW.

The magnet sensor cable (above) should have the same color sequence on either end, the metal ends should be visible in the slots, and the wires should stay in place against a gentle tug.

Want to dive deeper?

Some Advanced component testing notes are available.