In this chapter we are going to cover assembling the Arduino Board. This will require soldering and the first thing you will need is a decent soldering iron. You will need one with a relatively small tip. You will also want one that controls the temperature of the tip by controlling the power delivered. I am fond of Weller soldering stations, but there are a number of other good choices.
Lets start with the parts you are going to need:
The first thing we are going to do is solder the 2×20 pin female connector that is used to connect the Arduino Board to the Raspberry Pi. Now this connector is soldered to the 2×20 hole array, but needs to be positions on the bottom of the board since this board will sit on top of the Rasberry Pi. Position the connector on the board as shown below and solder the one pin shown. It is important that you apply solder to that one pin only. Once you have soldered more than one pin of the connector it will be very difficult to adjust it’s position and we want to make sure that it is seated properly before we solder the rest of the pins.
When making the solder connection, touch the soldering iron tip to both the pin sticking through the board and the pad to which you are soldering it. It is also important to heat the connection sufficiently so that the solder flows smoothly and does not clump up.
After you have soldered the first pin, pick up the board and you will probably find that the connector is crooked:
This is why we told you to solder only one pin. To fix this, pick up the board and put your finger on the connector. You can then heat the connection you just made to melt the solder which will allow you to re-position the connector as shown below:
Once you have the connector on straight, go ahead and solder the remaining 39 pins.
Next we are going to solder in the two capacitors. You need a 0.1uf capacitor (which is marked 104) and a 0.33uf capacitor (which is marked 334). Insert the capacitors into the corresponding places on the board and then cover them with a piece of tape to hold them in place while you solder them:
Once you have the capacitors soldered in place, remove the tape and cut of the excess leads.
Next we are going to attach the Arduino. Rather than soldering the Arduino directly to the board, we are going to use a couple of female headers to act as a socket so we can easily remove it if needed. We start by taking one of the 1×40 female headers and counting 15 pins from one end and then pulling out the 16th pin as shown below:
Then, using a hacksaw, cut the connector at the position of the missing pin. Then repeat the process to create a second 15 pin connector:
Now take the connectors for the Arduino, and insert them into the 15 pin connectors and then assemble the connectors and the Arduino on the board as shown below. Note, that at this point we have not soldered any of the connections.
Now solder the upper right and lower left pins of the Arduino as shown below:
Now turn the board over and solder the two corner pins on the underside as shown below:
Now make sure that the connector and Arduino are seated correctly and adjust the position by heating the pins as shown below:
Once you have the Arduino seated properly solder the remaining pins on the top and bottom. Once the solder has cooled, carefully remove the Arduino from the board. You may need to use a small screwdriver to pry the Arduino out as the fit is quite tight.
Now we will attach the six 2×3 headers on one side of the Arduino. Place the headers on the board and tape them in place as shown below:
Then turn the board over and solder only one pin of each of the 6 connectors as shown below:
If we turn the board over we will now probably discover that the connectors are, once again, not properly seated. With your finger on the connectors, heat each of the soldered pins so that you can seat the connector properly:
Once all of the six headers are seated properly, solder all of the remaining pins.
Now using the same technique install the other four headers on the other side of the Arduino as shown below. Also, cut a short piece of wire, bend it into a ‘u’ shape and solder it in the position circled below. This will supply 5v to the top 4 connectors on the right, which we will need for some of our sensors.
Next we will install a 1×2 pin male connector a jprx jumper position. First tape the connector into position as shown below:
Then turn the board over and solder only one of the pins. You can then make sure that the jumper is seated properly by holding the pin that is not soldered with your finger while you heat the other pin. This will allow you to adjust it’s position. Make sure that you are not touching the pin you are heating, however, or you will burn your finger.
We will now assemble the level shifter in a manner we used to mount the Arduino. From your 1×40 pin header stock, cut off two 6 pin pieces. Then insert the connectors that came with the level shifter into the two headers you just cut and assemble it on the board along with the level shifter module like you did for the Arduino:
Next assemble the voltage regulator by screwing it to the heat sink as shown below:
Now solder the voltage regulator onto the board at the position shown below. As before only solder one of the leads before you make sure that the voltage regulator is seated properly:
Finally we solder the screw terminal to it’s position on the board as shown below. As before only solder one of the pins until you have made sure that the heat sink is properly seated.
Now insert the Arduino and level shifter back into their sockets. Make sure the the Arduino is pointing the right way and that the orientation of the level shifter is correct with the the ‘low‘ and ‘high‘ sides matching the board. Also add the jumper to the jprx header. This will allow communication between the Raspberry Pi and the Arduino.