Assembling the Sun Tracking / Heliostat Control Circuit: Version 2.0


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This page explains how to wire together the current Arduino Sun Harvester Electronics System.

The previous (and more up to date) versions of this system based around the Stepper Power Control Boards can be found here if you still need the documentation.

We will start by listing all of the different components that you will need to build the circuit. Depending on whether your are controlling a sun tracker or a heliostat, or if you are controlling a single or multiple machines, you may be able to leave out certain components. It will be mentioned where you are able to do this further along.

Note that this circuit is meant to be used with “medium” (about 1m^2 of collector surface area) sized sun trackers and heliostats. Larger machines can be controlled by using more powerful driver boards, stepper motors, and a larger power supply, but that is not covered here yet. (I eventually plan to develop a board that allows you to easily connect larger driver boards to the existing system, but more on that later.)

Component List

Note that the various “Sun Harvester” circuit boards required for this project are currently only available through The Cerebral Meltdown Store. Click the link to learn more about the item.

The following items are not currently available through The Cerebral Meltdown Store and must be obtained through other suppliers. We will cover these items in more detail since they don’t have the store link descriptions like the above items do.

  • Arduino Microcontroller (Arduino Mega 2560 is recommended)
  • Power Supply for Arduino
  • Wires for Stepper Motors
  • Straight through Ethernet Cable
  • Power Cable for Driver Boards

Arduino Microcontroller

I recommend the Arduino Mega 2560 for this system. Make sure you get the 2560 and not the older Mega version. The Arduino Uno also works, but you might find the amount of available programming space is constricting.

Other Arduinos can be made to work, but you might not find it worth the trouble. It is recommended that you read the Sun Harvester Shield Arduino Compatibilities page if you are considering using a different Arduino.

Make sure to purchase your board through a reputable site. Adafruit and Sparkfun are two good U.S. suppliers. There are many knockoff boards available at lower prices, but their quality is often suspect.

Arduino Power Supply

You will need a 9V power supply to power the Arduino board. Take a look at this one from Adafruit.com as an example.

Wires for Stepper Motors

In the past, I have purchased my stepper motor wire from EBay. The stuff used for CNC machines works well. Remember that it may be exposed to the elements depending on your design, so choose your wire appropriately.

Straight through Ethernet Cable

When purchasing your Ethernet cable, make sure you get a straight through Ethernet cable (as opposed to a crossover cable). You can tell that its straight through by comparing both ends and seeing if the color patterns on the small wires inside the connectors match.

Direct burial Ethernet cable is best as it is able to withstand the elements.

Power Cables for Driver Boards

Each driver board in the system will require a two wire cable to supply power from the power supply.

The cheapest, best option that I have been able to find is landscape wire. As the name implies, it is designed to be used outside and will thus hold up to the elements.

 Assembling the Circuit

Attaching the Shield to the Arduino

When attaching the shield to the Arduino, line up the header pin on the shield indicated in the picture below so that plugs into pin 0 on the Arduino. If you are using the Arduino Uno two of the pins, A6, A7, will hang over the end as they are only available on the Arduino Mega.

Shield Connection to Arduino

 

Wiring the Breakout Board to the Sun Harvester Shield

If you are controlling multiple machines, then the next step you will take is to wire a breakout board (or multiple breakout boards) to the Sun Harvester Shield. If you are controlling a single machine and don’t plan on adding more in the future, then you don’t need the breakout board and can skip this step.

Click the link below to view the wiring for this step
Connecting the Breakout Board to the Sun Harvester Shield V1.0 

Wiring a single Driver Board directly to the Sun Harvester Shield or  multiple Driver Boards to the Breakout Board

If you are only controlling a single machine, then you only need a single driver board which you can wire directly to the Sun Harvester Shield.

If you are controlling multiple machines, then you will need one driver board for each machine which are wired to one or more breakout boards.

Click the link below to view the wiring for this step
Connecting the Sun Harvester Driver Board V1.0 to the Sun Harvester Shield V1.0 or Breakout Boards

Wiring the Limit Switches

You will need two limit switches for every machine that you wish to control.

Click the link below to view the wiring for this step
Connecting the Limit Switches to the Sun Harvester Circuit

Wiring the Target Changer Potentiometer and Wind Protection Mode Switch to the Sun Harvester Shield

If you are building a sun tracker, then you don’t need the target changer potentiometer. If you are building one or more heliostats, then it is recommended that you wire the potentiometer to the shield.

The wind protection mode switch is optional. Leaving it disconnected from the circuit will only prevent you from putting the machine(s) into wind protection mode. Note that the wind protection mode switch should not be the only failsafe you implement to prevent your machine from damage.

Click the link below to view the wiring for this step
Wiring the Target Changer Potentiometer and Wind Protection Mode Switch to the Sun Harvester Shield

Wiring the Arduino Power Supply

Just to clear up any confusion, the power supply for the Arduino and the power supply for the driver boards are not the same. The Arduino power supply is typically a small 9V supply while the driver board power supply is a bit beefier.

The wiring for the Arduino’s power supply is pretty obvious. Just plug it into the Arduino. If you happen to have a supply with no plug, you can also wire it directly to the Sun Harvester Shield by connecting the wires to the screw terminal in the upper right hand corner of the shield. Positive goes to Vin, and negative goes to Gnd.

Also note that the Arduino is powered through the USB cable as well, so remember to unplug both it and the power supply when working on the circuit.

Wiring the Driver Board Power Supply

If you are only controlling a single machine, then you will wire the driver board power supply directly to the driver board. Positive goes to M+, and negative goes to GND on the driver board.

If you are controlling multiple machines, then you will wire the driver board power supply to the breakout boards instead. You can technically use any of the terminals wired M+ or GND, but I usually use the one located at the upper right hand corner of the breakout board. If using more than one breakout board, I would then use the terminal on the left side to transfer power to the next breakout board. (This is shown more clearly in the Wiring the Breakout Board to the Shield and Driver Board Wiring sections above.)

The positive wire of the supply goes to M+ and the negative wire goes to GND on the breakout board.

Wiring the Stepper Motors to the Driver Board

The wiring for the stepper motors sold in the store is as follows.

Red wire –> A+
Yellow wire –> A-
Green wire –> B+
Grey wire –> B-

This color scheme will likely be different if using a stepper motor from another source.

Relevant Forum Link

If you’re curious, the history of this circuit along with information on how it works is available at the following page on this site’s forum. Note that the topic drifts around a bit since it is just a forum thread. Also, the more recent posts are more accurate than the earliest ones.

http://cerebralmeltdown.com/forum/index.php?topic=335.0

 

This documentation is part of the Open Sun Harvesting Project.

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