I don't know true seed count as of now. My electric drives work two ways; with a hydraulic rate controller or a rate controller I make based on an Adroid tablet.

For the first example, I have an Interface board that connects to the PWM output of a standard rate controller. It measures the PWM signal and makes the rate controller think a hydraulic drive is connected. By measuring the PWM and providing a feedback signal to the rate controller I am able to figure out how the rate controller is trying to spin a hydraulic drive. Normally a hydraulic drive spins the seed plates. So once I calculate the desired rpm needed by the rate controller based on row spacing, seed plate count, ground speed and needed population, I send the rpm number to the Control board. The Control board handles four rows individually. The slick thing is I send this data wirelessly from the Interface board to the Control board so the only connection I need between tractor and planter is power and ground.

The Interface board also connects to the 'section control' outputs. On a hydraulically driven planter farmers can use electric clutches on each row to engage/disengage the drives to minimize seed waste. I connect to these outputs to know which rows need to be on/off.

Each electric drive has an encoder that I use to measure rpm and adjust accordingly with a PID routine.

At current time, with a rate controller from another manufacturer or using my Android based rate controller, there is a 'Seed Monitor' It is connected to a seed sensor on each row of the planter. It is basically an optic sensor on the seed tube between the seed plate and the ground. It pulls low when the seed is in front of the seed sensor. Its not even close to being a 50% duty cycle.

If a farmer uses my rate controller, he is stuck with another display in his tractor that is the seed monitor. I want to integrate seed monitoring into my rate controller. I do display on my rate controller UI a population number but that is based purely from the encoder, not the seed being dropped into the ground.

The big thing in planting corn is being able to detect skips...when a seed is supposed to be dropped yet not. This is usually due to the vacuum pulling a seed against the seed plate not being correct. So I really need to be able to measure population based on seed drop from the seed sensor, display it on my Android UI and also throw up a flag on the UI when a skip is detected also.

I have started to work on the PIC32 chips but I am still running into the amount of available CCP/Input Capture pins not going up to 48 on a single processor. A 48 row planter is pretty rare but I need to be able to handle it. The majority of my customers are in the 12-16 row range.

Quote Originally Posted by EarlyBird2 View Post
You have a working system that counts each seed, works out the spread rate and adjusts the rate to meet a set value.

What sensor are you using to detect the seeds being dropped? I have used pulse counter chips as counters combine this with a clock timing of 100 ms will give spread rate seeds/second presumably tractor speed is also needed to give seed/metre.

From calculating spread rate the drill has to adjust the rate too the set rate. Will the PIC do this or is there some other control on board the tractor to do this?

I am thinking along the lines of 48 slave counters with serial connection to master controller. I can visualise what the slaves will do but can only guess at how the master will adjust the spread rate.