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OpenSprinkler v1.4u Build Instructions

(Note: all images below are ‘clickable’, in order for you to see the full-resolution details. )


To Begin: Parts Check
The kit includes all components you need to build OpenSprinkler v1.4u. The part list can be found on this page. As the picture shows, the kit includes the PCB, bags of components, LCD, and project enclosure.

Warning: electronic components are small and easy to lose. Before soldering, carefully put the components in a container, box, or mint tin. Sometimes a couple of components may get stuck on the sticker. DO NOT throw away the plastic bags until you are done with soldering.

Additionally, you need a sprinkler valve transformer (rated at 24VAC) and one or more sprinkler valves. These are not included in the kit. You need to purchase them separately. If you have set up a watering or irrigation system in your garden, you should already have these parts installed; if not, you can purchase them online or at local retail stores. They are available in many brands (Orbit, Hunter, Rainbird…) and a variety of places (Lowes, Home Depot, Amazon…). Check the F.A.Q. page for some additional information.
To give you a heads up, here are two high resolution images of the assembled board (front and back). Click the images to see them in full resolution.

Oct 2012 PCB Update version:

Part 1: Soldering
To begin, place the PCB onto a a vise, and turn on the soldering iron. (Optional: use a fume extractor to help remove solder fumes).

Remember: all images are ‘clickable’.




Start with the four 49.9 ohm resistors (taped together) and five 0.1uF ceramic capacitors (on a strip). These correspond to R2, R3, R4, R5 and C4, C5, CR, C7, C8. Click the image on the left to see where they are located on the PCB. These components are non-polar, so it doesn’t matter which direction you insert them.

To solder a resistor, bend its two leads as close as possible to the resistor body, then insert it to the PCB holes. To increase productivity, I usually insert multiple components at once, and use painter’s tape to fix them in place (see image on the left). You can use as many pieces of tapes as you need. Then flip the PCB and solder all leads. This way you can reduce the total number of times to flip the PCB. However, avoid inserting too many components such that the back of the PCB will be too crowded to get your soldering iron around.

After soldering, use a diagonal cutter to clip the leads just above the end of the solder joints.
(Oct 2012 PCB Update: X1 has been removed as the mcu is now programmed to use internal clock).

Next, solder three two crystal oscillators: X1 (8MHz, blue colored, three pins), X2 (25MHz, oval, two pins), and X3 (32.768KHz, small cylinder shaped, two pins). Click the image on the left to see where they are located. These components are non-polar.

Solder three ceramic capacitors: CT (220pF), CX1 and CX2 (18pF, on a strip of two or taped together). These three capacitors look very similar, but using a magnifying glass, you will see that CT is labeled 221, while the other two are labeled 180.

Also solder L2, a ferrite bead. It’s cylinder shaped, and non-polar.

Now you will solder a bunch of resistors. They are listed below:

  • RB, RRST, R1, RCL, RDA: five 10K resistors. Ring colors: Brown-Black-Orange. These come on a strip.
  • R8, R9: two 1K resistors. Ring colors: Brown-Black-Red. These two resistors come together on a strip.
  • RD+, RD-: two 47 ohm resistors. Ring colors: Yellow-Violet-Black. Again, they come together on a strip.
  • R6: 2.32K. Ring colors: Red-Orange-Red.
  • RT: 30K. Ring colors: Orange-Black-Orange.
  • R7: 1.5K. Ring colors: Brown-Green-Red.

Click the image on the left to see where they are located.

Next, solder Rsc, a 1 ohm resistor located on the left side of the PCB. The kit contains a strip of two 1 ohm resistors. The ring colors are Brown-Black-Gold. This is a current limiting resistor. It needs to be positioned upright. So bend one lead 180 degrees down, and solder it.

(Oct 2012 PCB Update: this is an optional step: if you want to power a WiFi adapter through OpenSprinkler’s USB port, solder the second 1 ohm resistor to the two holes below Rsc. This helps increase the current output of the +5V line).
(Oct 2012 PCB Update: solder RLED, a 100 ohm resistor located at the top of the PCB.)

The other 1 ohm resistor goes to RLED, located at the top of the PCB.

Above RLED is D4. It’s marked as a diode but is now replaced by a 100 ohm resistor. The ring colors are Brown-Black-Brown. So ignore the PCB silkscreen and solder the 100 ohm resistor here.

(Oct 2012 PCB Update: D1 is now replaced by a R3000 diode.)

Now solder three diodes: D1 (1N4001), D2 (1N5819), and D3 (1N4148). They are all located on the right of the USB connector.

To solder a diode, use pliers to gently bend the two leads to 90 degrees. Important: diodes have polarity, allowing current to flow only in one direction. Identify the end with a white stripe (the negative lead). This stripe should match the silkscreen on the PCB. Compare yours with the image on the left.

Next, solder IC2, an MCP1700-33 linear regulator from the IC bag. It has 3 pins and is shaped like a half cylinder, similar to a transistor. Note: be careful not to confuse it with the triacs from the screw terminal bag. Align it such that the semi-circle matches the PCB silkscreen. Then solder the three leads at the back of the PCB.
Next, solder L1, a 220uH (or 270uH) inductor. The label should read 221 (or 271). Inductors are non-polar.

Moving on, now solder C1, a 100uF electrolytic capacitor. It’s a relatively large component. Electrolytic capacitors are polarized: make sure the longer (positive) lead goes into the hole marked with +. To double check, there is a white stripe on capacitor body which points to the negative lead.


Similarly, solder C2 and C3, two identical 220uF electrolytic capacitors. They look similar to a 10uF capacitor that you will solder next. So please read the label on each capacitor to tell them apart. Again, pay attention to the polarity and remember the longer lead goes into to + hole. Don’t take things for granted: especially note that C2 and C3 have opposing positions on the PCB. Compare yours with the image on the left.

Now solder C6, a 10uF electrolytic capacitor located at the upper right corner of the PCB.


In the next step, solder three resistor arrays: RN1 (one 470 ohm, or depending on your package, it may be 680 or 220), RN2 and RN3 (two 330 ohm). Each resistor array has eight pins and consists of four identical isolated resistors. It is symmetric so you can insert it in any direction. You can identify the resistor array by reading its label. For example, 470 ohm resistor array should have ‘471’ in its label, 220 ohm array should read ‘221’, and 330 ohm array should read ‘331’.

After you are done with the resistor arrays, solder three right-angle pushbuttons: B1, B2, B3, as well as the RJ45 Ethernet connector. These are located on the right edge of the PCB. When inserting the RJ45 connector, be careful not to bend the pins.
Now move to the left side of the PCB, and solder the USB connector, as well as the PTC fuse. The PTC fuse is a yellow disc-shaped component. Use pliers to straighten the legs, then insert it to the PCB holes.
Next, solder the slide switch.


Now solder the coin battery holder. To begin, use a small amount of solder to tin the PCB pad. This is important to ensure the battery has good contact with the pad.
 
 
 
The image on the left shows the result of tinning. It should be a very thin layer.
 
 
 
 
 
Now go ahead and solder the battery holder.
Next, solder the 2×4 Extension Board Connector, located below L2.

Solder all IC sockets (from the IC bag). Be careful when inserting the IC sockets: make sure all socket pins go into the PCB holes correctly, and no pin is left out.

Every socket has a small notch (see the picture on the left) to help identify the orientation. This notch should match up with the silkscreen on the PCB.

Next, solder the 1×16 female pin header for the LCD. This pin header is located at the top of the PCB.
Now take out the LCD and the 1×16 male header. Solder the male header onto the LCD. The easiest way to do so is by making use of a breadboard to hold the pin header during soldering.
Next, solder the eight triacs (MAC97) T1-T8. Use your hand to bend the middle pin slightly backward, so that you can easily insert it to the PCB holes. Watch out the orientation of the triac.


 The last step of soldering is the screw terminals. Take them out from the screw terminal bag. Solder the AC In, COM, station terminals S1-S8, and the Rain Sensor terminal. Note that each terminal consists of two pieces. You can solder the board piece (with right-angle pins) first, then plug in the terminal piece.

Now you are all set with the soldering part! Check your circuit board with the image on the left.

Part 2: Testing
In this section, you will test the circuit and make sure it’s functioning. Start by inserting the CR1220 coin battery.
Now insert IC1 into its socket. This is a MC34063 switching regulator. Bend its pins slightly inward on a hard flat surface. While inserting, make sure no pins are left out or twisted. Make sure that its notch matches the notch on the socket. Refer to the image on the left.

Double check that you have inserted MC34063, not the other two ICs (DS1307 or ATtiny45). At this point, you should only have IC1 inserted. Leave the other ICs out. This can help reduce the possibility of damage in case something goes wrong with your power supply circuitry.



You will test power supply section now. First, slide up the power switch to turn it off.
 
 
Then, insert the two wires from your 24VAC sprinkler transformer to the AC In screw terminal on the left. AC power has no polarity, so it doesn’t matter which wire goes to which terminal. Tighten the terminal screws.

Important: use a multimeter to measure the AC voltage between the two transformer wires. Make sure it’s no more than 28VAC.
 
Now, slide down the power switch to turn it on. Important: (although this is unlikely) if anything burns or smokes, immediately turn off power. Check to see if there is any component visibly damaged. If you can’t figure out the problem, post a message in the forum and we will help you.


Voltage check: use a multimeter, measure the DC voltage between VIN and GND (+5V). These two pins are located in the 2×4 pinout area on the right of IC5 (shift register). Click the image to see where they are located.. The reading should be around 5.0 (it can range from 4.9 to 5.1).

Next, measure the DC voltage between VCC and GND, should be around 3.3.

It is crucial to check and ensure these voltage readings are correct, otherwise your controller may malfunction or get damaged.

After testing the voltages, power off the controller and unplug the AC IN terminal.

Now you can populate all ICs to their sockets: IC3 (DS1307) is an RTC, IC4 (ATmega328) is the MCU, IC5 (74HC595) is a shift register, IC6 (ENC28J60) is the Ethernet controller, and IC7 (ATtiny45) is a pre-programmed USBtiny ISP.

To insert an IC, bend its pins slightly inward on a hard flat surface. While inserting, make sure no pins are left out or twisted. Finally, check your PCB with the photo on the left to make sure all ICs are inserted to the correct position. You are all set! Take a moment to appreciate your work!

Part 3: Project Case
Now you can assemble the project case. First, check the case, including the top, bottom, four case screws (long, #4 3/8″) and four PCB screws (short, #4-40 3/16″).
Fix the PCB to the case bottom using the four short screws. Insert the LCD to the 1×16 female header on the PCB. Now you can install the plastic cover. Slide the cover from the right-hand side, because the holes on the right-hand side have to go through the pushbuttons and the Ethernet jack. Then press the cover down and make sure it is in good contact with the bottom.
Use a screw driver to carefully insert the case screws from the bottom of the case.
That’s it! Now you have installed the controller to the case. Note that the back panel of the case is wall mountable.

Some notes about using the controller:

  • You can pull the screw terminal blocks out, install wires and insert them back in. This allows you to easily change wires or temporarily disconnect the controller with wires.
  • Important: the case is not waterproof. While it can protect the circuit from accidental water splashes, it is by no means meant for outdoor use. DO NOT leave it outside unprotected. It should be placed in a garage or shelter that won’t catch rain or flood. If you must place it outdoors, enclose the circuit completely inside a waterproof sprinkler timer box (which you can get from local home improvement stores).

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