Hi, this is Wayne again with a topic “Projects with Ryan Slaugh: Making Your Own Proto Shield”.
One of the great things about arduino is the many ways you can connect sensors in different io to them via their shields, and these days there’s just about any shield you need. However, sometimes you do need a customized shield in this article. I’Ll show you how to make your own customized protoshield. The first thing you want to do in making your own shield kit is to look up the components you need and get data sheets on them in these data sheets.
You want to make sure that their operating voltages are going to be around what you already have available. For instance, in this case arduino having 5 volts, the interfaces i needed were to use 5 volts for their operating voltage. You also want to look at the interface voltage between digital i o and analog.
I o in this case since arduino uses zero to five volts. I wanted logic that uses zero to five volts. The circuits that i needed were a counter: a digital potentiometer and a digital to analog converter natively. The arduino can give you analog output on some of its digital pins by using pulse width modulation.
This allows you 8 bit resolution or 256 counts per full scale. So, if 5 volts is your full scale which it is on the arduino, then you get roughly 20 millivolts per count. However, i needed more resolution. Therefore, i chose a 12 bit digital to analog converter that gave you 4096 counts per full scale.
So, with 5 volts you have roughly 1 millivolt per count, often for digital to analog converters. You feed them in a parallel fashion, meaning you connect as many bits as it needs to convert up to your processor. In this case, 12, bits parallel, so you’d be using 12 outputs. You clock all of the inputs in at the same time, in a binary sequence, giving it how many counts. Therefore, how many volts you need. However, that uses a lot of digital.
I o to use fewer pins. I can use a serial input dac on pin 3 of this device. I can clock each bit one at a time using the falling edge of clock applied to pin 2. pin 1 controls the flow of data, whether the chip will accept or not and pin 4 can clear the data completely returning the output to 0.
a lot of Parts nowadays are surface mount. Therefore, i use a surfboard in order to solder them down and then put them into my project. These little boards have pads for many of the different devices, whether they be eight pin 16 14. Whatever i start by putting a little solder on one of the corner, pins or outside pins grabbing, my helpful tweezers and putting the component in place using the solder that i just placed down, this helps hold it in place. While i solder the opposite corner, pin the soldering tip i’m using here is called a mini wave. It allows me to pull the solder up onto the pins and pads and then the tip itself will pull all the excess solder away, leaving a nice clean solder joint. The component i’m working with might be surface mount, however, the protoboard itself is actually through hole so on the edge of the surfboard i’ll use, some old leads bend them into shape and solder them on effectively making this surfboard a through-hole component that will fit on the Protoshield from here, i’m going to take it to my breadboard just to do some tests, so i wire it up, hooking the inputs and the outputs to the arduino, making sure i have all the pins aligned correctly and then i’ll write a simple sketch to test it Out digital potentiometers are very handy when you need that variable resistance, that’s controllable from your arduino or any other processor. I’Ve chosen the ds 1868 for my needs.
It actually has two potentiometers, both 10k. It can be fed much like the serial input dac in that i actually clock in the data serially one bit at a time for this particular model. It takes 17 bits, total eight, each for the potentiometers and one bit to tell the system whether it’s stacked configuration both potentiometers in series or individual. The digital potentiometer is actually a through-hole part already, so i drop it into my breadboard.
I connect all the wires inputs and outputs write that simple, sketch and test the part. The last part i needed for this proto board was a counter. What a counter does is every time the clock changes state on the input in this case from high to low the count advances so, for instance, on the first drop falling edge, qa output would go high on the second falling edge, qa would go low and qb Would go high and would propagate through the system through all 12 bits. These devices can be helpful in frequency division or, in my case, for counting events that i don’t want the arduino to be counting every single event, but a multiple of events.
For instance, i can have it just looking at the 12th output, thereby counting every 12th event since we’re using another surface mount part in this counter. I get another surfboard get the part. Prepped grab my handy tweezers and use my mini wave tip to solder the part down making sure to clean up any large solder bridges from there. I go to my breadboard, connect the clock, input and the clear input and just one output.
I don’t really need to worry about any of the others. I just want to make sure that one is responding next, it’s time to start populating the actual protoboard itself. First, i start by placing the components that came with the protoboard few leds: resistors a reset switch and a switch for general use. Next come the header pin connectors.
I actually place them first in the arduino then place the protoshield on top of it that actu this actually helps keep things straight. So the soldering goes a lot easier than trying to do it. Freehand once they’re all soldered in i can remove the arduino from the protoshield from there it’s placing my ics finding the best layout orientation, where all the components will fit. The next step is to wire the entire protoboard up to match this schematic you’ll notice in the lower right hand corner another component has been added.
This is an analog temperature sensor. I work its output into the analog input of the arduino start. This process, one connection at a time taking wires point to point each time, taking care that no wires are shorted and that the connections are secure. After i’m done with that, i like to do a quick check to make sure that the 5 volt rail and 3.3 volt rail are not shorted to ground, so i quickly check it with my own meter.
Finally, i can download a sketch and test the board. I wrote a simple sketch that has a menu driven selection to where i can exercise each component. It’S included with this video. I can test the potentiometer value, which it cycles from low to high through all the combinations.
I can also test the analog out. In the same manner, it just sends the bit stream taking it from low to high and back again from there. I test the analog input now right now. This is just raw counts, but i can convert these for fahrenheit celsius or kelvin to look at the counter output. I use a logic analyzer. I clip it to the first eight bits, the first one being the clock.
Then i run it through the analyzer. As you can see here, my channel zero is my clock going from high to low repeatedly and then channel one through seven are the counter outputs counting up digitally there’s a large selection of ics out there that you can match with your arduino. To give you a multitude of input and output abilities, taking a good look at each one’s data sheet, you can form a good, solid design and with a little work with wiring, you can come up with infinite possibilities of things to control, with your arduino and your Own custom protoshield happy building. You .