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 so we can try to help if we're able. 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

Here are links to pages for the 2024 model, 2023 model, 2022 model, 2020 model, and 2018 model. 

Firmware updates (or reload to new ESP32)

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. You can also use this page if you wish to load the firmware onto a new or misbehaving ESP32 module. 

Replaceable parts

Here are some sources and notes on replacing a few key parts.

General troubleshooting

These notes were originally written for the 2022 model/design but may have relevance to earlier models and to 2023-2024. You are welcome and encouraged to ask for further assistance or clarification: please email David at david_h_brown@uri.edu. I often make updates here when you do as well as replying directly, so that can help others as well.

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 makes its initial noise but then stops or restarts

CAUTION: The laser may intermittently be on during this failure. Always place the cap over the laser module during testing.

Possible causes we've seen include:

• Low battery (easy)

• Failed stepper driver (rare; easy to test and replace)

• Failed servo (unhappily more common; not too hard to test; more work to replace)

Battery check: Are you sure the battery has a full charge? A lead-acid 12V battery is over 13V when fully charged and will be unhappy if discharged below about 11.8V. A grower called reporting his scarecrow persistently restarting with only the warning tones repeating again and again (2022 unit). I mistakenly asked the grower to try disconnecting the servo, but that didn't help (sorry for the extra work, Carl). Turned out the battery was low; swapping with the one on a second working scarecrow "fixed" the first. Secondary symptom/clue in this case was that the arm didn't rotate during the warning tones. I suspect that the battery was enough to power the microcontroller but then when the laser/servo switched on, that load dropped the remaining voltage too low for anything, causing the microcontroller to restart (which turns the laser and servo back off) and try again... and again... and again...

Stepper driver failure/overload: we've seen this once in a 2024 unit that was returned for help with service after disconnecting the servo (below) didn't help. Confusingly, when set to an operating mode, it repeatedly played the tilt sound while drawing more power than it should (0.8A vs. about 0.23A). However, in test mode, the tilt sensor proved to be fine. In test mode the arm barely rotated in a very jerky manner. Replacing the stepper driver worked. I also noticed some dust or grit in one of the socket pins when I put the new one in (there was a lot inside the scarecrow), so there's conceivably a chance that was the problem, but I don't believe the grower had any reason to take out the original stepper driver and allow dirt in.

To test whether this could be the cause, power off the scarecrow, set the jumper to test mode, and remove the stepper driver at the right hand side of the board by pulling it straight up from the sides. It's next to where the 4-wire cable [blue/red/black/green] connects the motor to the main board. The arm won't rotate, but if test mode works otherwise, this is a likely source of the problem. (If you still have a problem, put it back.)

Servo failure/overload: We started seeing more servo failures than before in 2023 units and mostly solved the problem for 2024 by reducing the speed at which the servo moves. It's also possible to cause this sort of failure if the laser is forced too high or too low, jamming the servo. I've seen jammed servos that got so hot the plastic gears melted!

A failed servo can draw too much current and trip one of the self-resetting fuses on the circuit boards. This cuts power to the microcontroller, turning everything else off (including the servo), allowing the fuse to reset so the scarecrow tries to start again (and fails again).

This failure 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. 

 Easier first check: 

The servo, laser, and tape sensor will all be disconnected if you carefully unplug the 8-wire "Slip Ring" connector located on the side of the board away from the key switch. There is a ridge going all around the plug that you will need to pull straight up -- one end then the other rocking back and forth is okay; just don't pull on the teeny wires. 

With the cap on the laser(s), start up the scarecrow. If the problem has gone away, it's one of these, but not necessarily the servo. (If the problem doesn't go away, it's probably not one of these.)

 To verify the servo is the problem, disconnect the servo connector only (inside the rotating arm in 2022 and 2023 models; see assembly guide; for 2024 models and 2025 Berry Prototype, see below). 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; see the page where we list replaceable parts. 

2024 and 2025 Berry Prototype servo connections

The servo connector is a black rectangular plug with three wires near a white rectangular plug with two wires (for the laser). To disconnect a servo, just pull the plug straight back out the side of the cap that is over the small circuit board that's on top of the rotating arm. They are held by the friction of the pins (and the cap). 

To reconnect, make sure you align the darkest wire to the outside (black or brown); lightest wire to the inside (white or yellow) as you push the tip of the plug back through the opening in the cap. The three shiny points you can see about ½" (13mm) in from the edge of the board are for the right-angle pins you are trying to push the plug back onto. It can be tricky; try tilting the tip of the plug up so it slides along the bottom of the circuit board until it is stopped by the pins hitting the plug housing. Then back off just the tiniest bit, level the plug, and push it onto the pins.

These photos show the scarecrow upside-down as it’s easier to work on the scarecrow that way: 

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

This sounds like your scarecrow is in self-test mode. Please take a look at... 

• section 7.3 in the 2022 Operation Manual, 

• section 5 in the 2023 Operation manual, or

• section 8.5 in the 2024 Operating 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

2023-2025: If water gets into a RJ45 connector, this can short-circuit the 12V power supply to the 3.3V control lines that go directly to the microcontroller and cause it to fail. Typically the light on the control board will be on, but the power LED on the microcontroller will be off and a part on the microcontroller can get very hot. This can require replacing multiple parts.

2022: 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).

2022-2024: 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; instructions are at https://davidhbrown.github.io/laserscarecrow-firmware/. 

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. More information has been added about these possibilities above. (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) 

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). 

Want to dive deeper?

Some Advanced component testing notes are available.