S2Duino Build Instructions

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Here are the steps for building the S2Duino. Before beginning be sure to visit the parts page (click on the button above), and verify you have all the parts and supplies.

  1. Diode
  2. Power Connectors
  3. Power Circuit Capacitors
  4. Voltage Regulator & Power Select Jumper
  5. Power LED and Resistor
  6. Test Power Circuit
  7. Pin 13 LED and Resistor
  8. FTDI Header and Reset Capacitor
  9. Reset Switch and Reset Pin Pullup Resistor
  10. IC Socket
  11. 16 MHz Crystal and Capacitors
  12. Headers
  13. Finishing up
  14. Install IC and Test
Step Photo Description


S2Duino (1-1) Diode


Let’s jump right in! Bend the wires for the 1N4001 Diode (D1) and insert into the holes. Diode’s are polarity sensitive. Be sure to match the strip on the diode to the diagram on the board.This diode guards against the use of a barrel jack with center negative polarity or the reversal of the positive and negative leads to the XH2.54 connector.

S2Duino (1-2) Diode Bend the wires out so that when the board is turned over, the diode remains in place close to the board.
S2Duino (1-3) Diode Solder the wires. I’m assuming that you know how to solder. If you are unfamiliar with soldering techniques, take some time to practice. Here are some links to soldering how-to guides. Note: there is no substitute for practice.
S2Duino (1-4) Diode Clip the wires close to the board using flush cutters.


S2Duino (2-1) Power Connectors


Install the barrel jack connector and the XH2.54 connector to the board. The keyed portion of the XH2.54 connector faces toward the barrel jack.

For future reference, the terminal positioned nearest the center of the board is ground and the terminal near the edge is positive.

It is not necessary to solder both the barrel jack connect and the XH2.54 connector. You may only wish to solder one or the other depending on how the board is going to be used.

S2Duino (2-2) Power Connectors If the connectors don’t stay in place when turned upside down, use a small piece of tape to temporarily hold in place while soldering the first terminal.

The barrel jack extends past the edge of the board so that it can be inserted into the wall of a project box or similar.

S2Duino (2-3) Power Connectors Solder the connectors. After the first terminal is soldered, double check to see that the the jacks sit close to the board. If not, it’s easier to de-solder one connection than two or three.
The barrel jack requires quite a bit of solder to completely cover the holes.
The leads to both these connections are rather short and don’t need to be clipped.


S2Duino (3-1) Power Circuit Capacitors


Insert the 47uF 25V capacitor (C2) into it’s place on the board.

Electrolytic capacitors are polarized. They have a positive and negative wire. There are a couple of ways to tell which is which. The easiest is by looking at the length of the wires. The longer of the two wires is the positive side. The other way to tell is by looking for a strip on the side of the capacitor. The strip aligns to the negative side.

S2Duino (3-2) Power Circuit Capacitors Do the same for the 100uf 6.3V capacitor (C4). Thread the longer of the two wires through the hole nearest to the plus sign and the shorter wire through the opposite hole. Bend the wires on the underside to hold the capacitor in place for soldering.
S2Duino (3-3) Power Circuit Capacitors Now find two 0.1uf capacitors marked 104 (C1,C3). These are ceramic capacitors and are not polarized. Their wires can go in either hole. Position these two capacitors and bend the wires to hold them in place.
S2Duino (3-4) Power Circuit Capacitors Capacitors store small charges. The purpose of these four capacitors is to help smooth out any fluctuations in the current that might be coming down the wire. By storing a small charge when there is current, and releasing the charge when there is a dip, they keep a constant current flowing through the circuit. We are using two capacitors on each side of the voltage regulator to ‘clean’ both high frequency and low frequency fluctuations.
S2Duino (3-5) Power Circuit Capacitors Solder and clip the wires


S2Duino (4-1) Voltage Regulator & Power Select Jumper

Voltage Regulator & Power Select Jumper

Place the Voltage regulator (IC1) in it’s place. The metal part that extends above the body is a heat sink. The heat sink needs to be positioned corresponding to the double line diagram on the board. It won’t have a snug fit. The regulator’s leads are larger near the body of the regulator so it will not touch the board. This is normal.

S2Duino (4-2) Voltage Regulator & Power Select Jumper Use tape to hold the voltage regulator in place and straight. Since the fit is not snug, the regulator will have a tendency to skew one way or another.
S2Duino (4-3) Voltage Regulator & Power Select Jumper The tape helps to make sure the regulator is straight and square.
S2Duino (4-4) Voltage Regulator & Power Select Jumper After soldering one lead, you can remove the tape and check the alignment.
S2Duino (4-5) Voltage Regulator & Power Select Jumper Finish soldering the regulator into place.
S2Duino (4-6) Voltage Regulator & Power Select Jumper Clip the leads.
S2Duino (4-7) Voltage Regulator & Power Select Jumper Place the 3 pin header power selector into it’s holes. This will have a much more snug fit. The individual leads in these headers can shift somewhat, so be sure that the leads are aligned with the majority of the lead on top and just enough of the lead extending below the holes to solder.
S2Duino (4-8) Voltage Regulator & Power Select Jumper Solder. No clipping should be necessary.
S2Duino (4-9) Voltage Regulator & Power Select Jumper Don’t forget to place the jumper on the correct pair of headers leads, otherwise the power circuit won’t work when tested. When the jumper covers the EXT and center pins, power will be routed from the power connectors. When the jumper covers the USB and center pins, power will be drawn from the FTDI connector.


S2Duino (5-1) Power LED and Resistor

Power LED and Resistor

Install the 1K resister marked Brown Black Red (R3). This resister is installed upright to conserve horizontal space. As with other components, bend back the leads to hold it in place.

S2Duino (5-2) Power LED and Resistor Install the green LED (D2).[break][break]LED’s are polarized. Like the capacitor installed earlier, the longer lead is positive. Additionally, LEDs have a flat portion on the circular body. The flat portion is on the negative side.
S2Duino (5-3) Power LED and Resistor  Bend the leads to hold the LED in place while soldering.
S2Duino v4 (5-4) Power LED and Resistor
S2Duino (5-5) Power LED and Resistor  solder the components. Clip the leads.


S2Duino (6-1) Test Power Circuit

Test Power Circuit

At this point in the build, we can test the power circuit. Apply at least 7 volts to either the barrel jack or the XH2.54 connector. On the barrel jack, center is positive. on the XH2.54 connector, positive is closer to the edge of the board. If polarity is reversed, the circuit will not work, since the diode will block the current. If the power circuit is working properly, the green LED will light.[break][break]If it does not work, troubleshoot the problem. Check that the jumper is in the correct place. Verify the power source is working and providing sufficient voltage. Verify polarity sensitive components are facing the correct direction. Double check that all the steps above were followed.[break][break]If you follow the traces on the other side of the board, you will find that the power LED is at the other side of the power circuit, even though it appears on the top to be positioned right next to it. This helps ensure that if the power LED is on, you can feel confident that the traces throughout the power circuit are not broken.


S2Duino (7-1) Pin 13 LED and Resistor

Pin 13 LED and Resistor

Now install the the Pin 13 LED (D2) and the pin 13 LED resistor [brown black red] (R2). This is added as a convenience for testing that everything is working properly. Pin 13 is used traditionally as the target of the basic ‘blink’ sketch. By having an LED built-in to the board, you can verify that the board and micro-controller is working properly without having to dig out an LED and resistor.

S2Duino (7-2) Pin 13 LED and Resistor


S2Duino (8-1) FTDI Header and Reset Capacitor

FTDI Header and Reset Capacitor

Place the 6-pin male header in the holes marked FTDI and solder in place. Install FDTI reset pin capacitor (C7).


S2Duino (9-1) Reset Switch and Reset Pin Pullup Resistor

Reset Switch and Reset Pin Pullup Resistor

Insert the reset switch (SW1) and reset pin pull-up resistor [brown black orange] (R1). Solder into place.


S2Duino (10-1) 16 MHz Crystal and Capacitors

16 MHz Crystal and Capacitors

Install the 16 Mhz cyrstal (Q1) and the 22 pf capacitors (C5, C6). These components are not polarized, so either direction works fine.


S2Duino (11-1) IC Socket

IC Socket

Install the 28 pin IC socket and solder into place. Note the direction of the socket. the notch on one of the shorts sides matches the notch graphic on the board. If you accidentally solder this in the wrong direction, it’s not a big deal. It’s just important that you remember which direction the chip is installed.


S2Duino (12-1) Headers


This is probably the hardest part of assembly. Installing the headers can be tricky to hold in place while soldering. To help, place a few male headers in a breadboard like the photo to the left shows. the number of headers is not important. I put 3 in one place 2 in the next and 3 in the next, but this was simply random based on what I had handy. 2 or more headers should be sufficient.

S2Duino (12-2) Headers Then place the headers to be soldered upside down on the before mentioned male headers.
S2Duino (12-3) Headers Then place the board on top the headers. Solder them in place, being careful to keep the headers perpendicular to the board surface. Alternatively, you can try to tape the headers in place as has been done with other components.[break]repeat this process with all the included headers. There are (3) 9 pin headers, (2) 3 pin headers and (4) 6 pin headers.


S2Duino (13-1) Finishing UP

Finishing up

Here is the finished board. A lot of solder has flux which is necessary for well formed solder pints, but can be corrosive if left on the board. It’s not a bad idea to clean the solder joints with Isopropyl alcohol or acetone and an old tooth brush to clean off the resin.


S2Duino (14-1) Install IC and Test

Install IC and Test

Now is the moment of truth. Install IC (IC2) making sure that the notch on the top of the chip matches the notch on the board.

The ATMega328P-PU included in the kit is pre-loaded with the UNO bootloader and the ‘blink’ sketch.

Plug Myduino into your power source. The green light should illuminate and the yellow light should flash in one second intervals.