Inspired by all the cool projects I have seen on here, I thought I would try my hand at my own project. This past winter I built my own planter down force monitor. I put precision planting weight pins on a couple rows on the planter. I then designed my own pcb to mount an ESP32 and an HX711 load cell amplifier on the tool bar ahead of each row. The ESP samples the load cell several times a second and created a 100 value array. It then finds the median value of the array, the lowest value of the array and calculates the ground contact percentage. (I have the ground contact threshold set at 20 lbs. Values under 20 lbs it counts as lost ground contact)
The ESP 32 for each row with a weight pin sends the values median, lowest and ground contact to another ESP 32 in the tractor cab. The receiver ESP 32 then averages the values from the row modules and displays them on an LCD display in the cab.
I have been running it all spring. The data seems stable and useful. I am using the data to make decisions about how to set my manual downforce springs. I put relays for future development on the display pcb in the cab thinking in the future code could be written to automatically control down force air bags on the corn planter.
I think the most likely outcome is I will add air bags and a manual pressure control in the cab for next season and make adjustments from the cab myself.
If there is any interest in this project I can get more details later.
Really nice little project.
How do the planter mounted boards communicate with the cab? Wired or wireless?
And same for the cab mounted board, is it just I2c to the LCD?
Yes, it’s wireless. The progression of the project was, I noticed the wires were color coded the same on a weight pin as most other load cells, so that got me thinking. I then connected a hx711 to an Arduino Nano and bought a weight pin. I then found I could read the weight pin. Next I added an I2C LCD display and thought I would just run wires to the cab until I learned I2C would not work beyond 3-4’. Next I started to look into Bluetooth modules for communication, but while I was doing that I stumbled on to ESP Now communication protocol. It is a proprietary wireless communication for multiple ESP 32 boards to send small data packets on a network. It was just what I needed to send sensor data to the tractor. Then with Chat GPT I was able to put together some code to make it all work.
Here is a picture of the board in the cab display box. All it is is really just a spot to mount the ESP 32 with a power supply and a connector to connect the I2C LCD display. There are two relays I put on the board as well for future use if I would ever try to automate the downforce control.
We are about 80% done with planting it you, Pat or anyone else is interested I can give more details about the project in the future.
This is an awesome project! Well done! Definitely something I’d like to try.
I’m curious if you find yourself adjusting your springs any during the course of having a full hopper of seed to being 1/2 full or nearly empty? I usually set mine with full hoppers and plant away but have often thought there could be 80lbs or more of difference from start to finish.
There is not much to the planter wiring. The smart pin has 4 wires. Red, black, green and white. They hook to the 4 pin block on the pcb which are directly connected to 4 pins on the green hx711 load cell amplifier. The other 2 wires on the other block are just power and ground 12v. When you look at the picture you see red, black, white and yellow. Those were the colors on the 4 strand wire I had. The yellow is connected to the green of the load cell.
It is sensitive enough to notice 80 lbs. When I go up a notch on my downforce springs I see about a 50 lb change. I usually run on the heavy side as some of the down force on farm research generally says error on the heavy side. One thing I have noticed is I plant headlands last now that I have RTK autosteer. Usually I loose ground contact when planting headlands. Even in good conditions I often go down to 80-90% ground contact planting headlands even when I was running 100% ground contact with 75 lbs of margin in the field.
The protocol is called ESP Now, it is Expressif’s proprietary language for wireless communication between their ESP line of boards. It works quite well, I never had any problems with communication.
This link is to a tutorial on how to use ESP 32. His sample code is part of the basis for the code I used chat GPT to write for the downforce monitor
