{"id":475,"date":"2017-03-02T08:00:33","date_gmt":"2017-03-02T16:00:33","guid":{"rendered":"http:\/\/www.autodesk.com\/products\/eagle\/blog\/?p=475"},"modified":"2023-09-26T15:44:09","modified_gmt":"2023-09-26T22:44:09","slug":"schematic-basics-part-2-nets-and-values","status":"publish","type":"post","link":"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/schematic-basics-part-2-nets-and-values\/","title":{"rendered":"Schematic Basics Part 2: Nets and Values"},"content":{"rendered":"

Schematic Basics Part 2: <\/span><\/h1>\n

How to Add Nets and Values to Your Symbols in Autodesk EAGLE<\/span><\/h1>\n

Welcome back! \u00a0This is Schematic Basics Part 2. In our<\/span> previous blog<\/a>,<\/span> we covered how to create your first schematic in Autodesk EAGLE and how to place symbols. In this blog, we\u2019re going to take things a step further by learning how to add connectivity between your schematic symbols with the help of <\/span>Nets<\/i><\/b>. Then once everything is connected, we\u2019ll cover how to add values to parts. Let\u2019s get started!<\/span><\/p>\n

First Things First<\/h2>\n

Like in Schematic Basics Part 1<\/a>, there are a few details that we need to cover before soaking in some knowledge:<\/span><\/p>\n

Use Nets, Not Wires<\/h3>\n

There are two kinds of wires in Autodesk EAGLE, the standard <\/span>Wire<\/b>, and the <\/span>Net<\/b>. But which do you use when creating connections between your symbols? Here\u2019s how it works:<\/span><\/p>\n

You <\/span>don\u2019t<\/span><\/i> want to use the <\/span>Wire\u00a0\"wire-icon\" <\/b> icon when adding nets to your schematic. The only reason to use the Wire option is for adding detailed line drawings to your schematic.<\/span><\/p>\n

You <\/span>do<\/span><\/i> want to use the <\/span>Net<\/b> \"net-icon\" icon to wire up your schematic symbols. This will always be your go-to action when you need to connect your symbols together.<\/span><\/p>\n

This can be a tad confusing at first, but use the icon symbols as a\u00a0visual guide. The Net icon is a green wire representing connectivity, which is exactly its purpose. Whereas the Wire icon has a line and a pencil. <\/span>Use this feature, not the pencil for creating sketches.<\/b><\/p>\n

Junctions and Overlaps<\/h3>\n

Next, you\u2019ll need to understand the difference between <\/span>junctions<\/b> and <\/span>overlaps<\/b>. Here\u2019s an example of a junction:<\/span><\/p>\n

\"junction-point\"

Be on the lookout for a node to identify net connection points.<\/em><\/p><\/div>\n

You can always identify a junction by the large circle that connects two intersecting nets. This means that these nets are sharing an electrical connection. This is a universal symbol, so be on the lookout whenever you see it in any schematic down the road.<\/span><\/p>\n

Now, when nets aren\u2019t meant to share an electrical connection, then they will overlap. In Autodesk EAGLE, you\u2019ll know when two nets are overlapping when there is no junction point between their intersection, like this:<\/span><\/p>\n

\"overlapping-nets\"

These nets don\u2019t share an electrical connection, notice the lack of a junction point.<\/em><\/p><\/div>\n

What\u2019s so important about all of this? How you place your nets in your schematic will determine how your parts are electrically connected\u00a0and will affect your PCB layout as well. If you don\u2019t get this part right now, then your circuit won\u2019t work as intended, and that\u2019s no fun.<\/span><\/p>\n

That\u2019s it for the getting starting details. Let\u2019s begin wiring up your schematic with nets!<\/span><\/p>\n

 <\/p>\n

Step 1 – Adding Your Grid<\/h2>\n

Before you go about adding any nets, let\u2019s first add a grid to your schematic. This will make it a lot easier to see how all of our symbols are aligned and will let you easily see what course your nets will align with when placed. Follow these steps to turn on your grid<\/span><\/p>\n

 <\/p>\n

    \n
  1. Select the <\/span>Grid \"grid-icon\"\u00a0icon in the top-left corner of your interface.<\/span><\/b><\/li>\n
  2. In the <\/span>Grid Dialog<\/strong>, change the Display to <\/span>On<\/strong>.<\/span><\/li>\n
  3. All other settings can be left as is. Select <\/span>OK<\/strong> to finalize your changes. <\/span><\/li>\n<\/ol>\n

    <\/b><\/p>\n

     <\/p>\n

    Turning on your grid will make a lot more sense once you start connecting nets, and it works much better than the blank white canvas with which that you started. <\/span><\/p>\n

    \"eagle-grid-visible\"

    With the grid visible in <\/em>EAGLE, it\u2019s now easy to align and place nets.<\/em><\/p><\/div>\n

    Now that you have some structure in place with a grid let\u2019s move on to connecting your symbols with nets!<\/span><\/p>\n

    Step 2 – Connecting Your Symbols with Nets<\/h2>\n

    Connecting your symbols with nets is simple. Follow these steps to get started:<\/span><\/p>\n

     <\/p>\n

      \n
    1. Select the <\/span>Net\u00a0\"net-icon\"\u00a0icon on the left-hand side of your interface.<\/span><\/b><\/li>\n
    2. Next, left-click<\/strong> at the end of the first pin from where you would like to start your net connection.<\/span><\/li>\n
    3. T<\/span>hen, drag<\/strong> your mouse away from your first pin, and you should have a bright green net that follows your mouse along your grid lines.<\/span><\/li>\n
    4. To finish the net, left-click on the end of another pin to make the connection. Your net will turn a dark green color let you know that it\u2019s placed.<\/span><\/li>\n<\/ol>\n

      In our example shown below, we started with a simple net connection between the bottom of our R3<\/strong> resistor and the top of our R4<\/strong> resistor. Pretty easy? Now let\u2019s find out how to add some junctions.<\/p>\n

      \"net-connection-r3-r4\"

      Resistors R3 and R4 now connected with a dark green net.<\/em><\/p><\/div>\n

      Step 3 – Adding Junctions to Your Nets<\/h2>\n

      As we mentioned above, adding junctions to your schematic allows intersecting nets to share an electrical connection. To add a junction, you can do it in one of two ways:<\/span><\/p>\n

      Option 1 – Adding a Junction While Adding a Net<\/h3>\n

      We need to add a net that connects between Pin 3 on our 555 timer and our R3 and R4 resistors. This will require a junction. You can follow these steps in our example to add one:<\/span><\/p>\n

       <\/p>\n

        \n
      1. Select the <\/span>Net \"net-icon\" icon on the left-hand side of your interface.<\/span><\/b><\/li>\n
      2. Next, left-click<\/strong> on the end of Pin 3 to start your net.<\/span><\/li>\n
      3. Then left-click<\/strong> again in the middle of the R3\/R4 net to finalize the connection, which will automatically create a junction.<\/span><\/li>\n<\/ol>\n

        <\/b><\/p>\n

         <\/p>\n

        \"pin3-net-junction\"

        Pin 3 on the NE555 timer now has a junction connecting it to the net between R3 and R4 resistors.<\/em><\/p><\/div>\n

        Option 2 – Adding a Junction to an Existing Net<\/h3>\n

        Creating a junction while adding a net is easy, but what happens if you have two intersecting nets that don’t already have a junction marker? You can add one manually:<\/span><\/p>\n

         <\/p>\n

          \n
        1. Select the <\/span>Junction \"junction-icon\"\u00a0icon on the left-hand side of your interface.<\/span><\/b><\/li>\n
        2. Left-click<\/strong> on the intersecting point between two nets where you want to add a junction.<\/span><\/li>\n
        3. This will open up the Connect Net Segments Dialog<\/b>, confirming that you want to connect (merge) two nets. Select the desired net name and choose <\/span>OK<\/b>.<\/span><\/li>\n<\/ol>\n
          \"junction-net\"

          See that intersection point between our C1 capacitor and the net? It needs a junction added. Otherwise, no electrical connectivity will be shared.<\/em><\/p><\/div>\n

          Step 4 – Deleting Your Nets<\/h2>\n

          You just added both regular nets and junctions, what happens if you make a mistake? Here is how to delete a net: <\/span><\/p>\n

           <\/p>\n

            \n
          1. Select the <\/span>Delete \"delete\" icon on the left-hand side of your interface.<\/span><\/b><\/li>\n
          2. Left-click<\/strong> the segment of a net you want to delete, and it will be removed. If this net had a junction attached it will also be deleted. <\/span><\/li>\n<\/ol>\n

            <\/b><\/p>\n

             <\/p>\n

            Now you have all the basic building blocks you need to wire up your symbols. The completed schematic is below. Give it a try!<\/p>\n

            Note – <\/b>You\u2019ll notice that Pin 5 is not connected on this schematic. That\u2019s done for a very good reason, which we\u2019ll be exploring in Part 3 of this Schematic Basics series.<\/span><\/p>\n

            \"completed-circuit\"

            Our schematic circuit wired with all its nets, except Pin 5, but we\u2019ll save that for later.<\/em><\/p><\/div>\n

            Optional- Net Angles<\/h3>\n

            You might have noticed that when you select the <\/span>Net\u00a0\"net-icon\"\u00a0<\/b>icon, quite a lot of new options appear at the top of your interface. These options allow you to set a different bend radius on the net with which you’re working. By default, all of your net connections will use the <\/span>Wire bend style 0<\/b>, which is a 90-degree bend, which is fine for most schematics.<\/span><\/p>\n

            However, you may want a 45-degree bend angle for your net. To do this, select the <\/span>Wire bend style 1 <\/b>and then add your net as described in Step 2 above. You\u2019ll notice that the net will now automatically bend at your desired angle as shown below:<\/span><\/p>\n

            \"45-degree-net-bend\"

            Here\u2019s a <\/em>45-degree net made possible with Wire bend style 1.<\/em><\/p><\/div>\n

            There are a few other options in this menu, allowing you to add things like a custom radius, or even changing how the net line appears as either solid (continuous), dashed or dotted. Feel free to play around with these options to see how they make a difference. When you\u2019re ready, let\u2019s move on to the final step in today\u2019s schematic journey, adding values to your symbols.<\/span><\/p>\n

            Step 5 – Adding Values to Your Symbols<\/h2>\n

            Adding values to specific parts like your resistors, capacitors, etc. will make it easy your reference in the future. Here\u2019s how to add values to your symbols:<\/span><\/p>\n

              \n
            1. Select the <\/span>Value\u00a0\"value-icon\"\u00a0<\/b>icon on the left-hand side of your interface. <\/span><\/li>\n
            2. Left-click<\/strong> the symbol you want to add a value. In our example, we\u2019ll choose our R1 resistor. <\/span><\/li>\n
            3. In the <\/span>Value Dialog<\/b>, enter value 1k for your symbol and then select <\/span>OK<\/b>.<\/span><\/li>\n<\/ol>\n

              That\u2019s all there is to it! As you can see in the image below, our R1 resistor now has a 1k value listed below its name. If you\u2019ve been following along with our example circuit, then go ahead and add the remaining values for the three resistors and capacitor as well.<\/span><\/p>\n

              \"resistor-with-1k-value\"

              Our R1 resistor with its newly added 1k value.<\/em><\/p><\/div>\n

              Quick side note – If you also want to change the name of one of your symbols, it\u2019s almost the same process as changing the value. The only difference being that you\u2019ll select the <\/span>Name\u00a0\"name-icon\"\u00a0<\/b>icon\u00a0<\/b>instead of the <\/span>Value\u00a0\"value-icon\"\u00a0<\/b>icon.<\/span><\/p>\n

              Step 6 – Deleting or Changing Your Symbol Values<\/h2>\n

              Let\u2019s say you need to delete or change a symbol value that you just added. You might be thinking to use the <\/span>Delete <\/b>action, but this will end up removing the entire symbol and value! This is definitely not what we want, so here\u2019s the better way to do it:<\/span><\/p>\n

                \n
              1. Select the <\/span>Value \"value-icon\"<\/b> icon on the left-hand side of your interface.<\/span><\/li>\n
              2. Left-click the name of the value that you want to remove or change. <\/span><\/li>\n
              3. In the <\/span>Value Dialog<\/b> that opens, you can either delete the name to remove it or change it.<\/span><\/li>\n
              4. Once your change is made, select OK<\/b>.<\/span><\/li>\n<\/ol>\n

                Mission Accomplished<\/h2>\n

                You did it! Your schematic should now be fully wired with a set of values added for all of the parts that needed it. Here\u2019s how your schematic should look\u00a0completed:<\/span><\/p>\n

                \"completed-schematic\"

                Our completed schematic, including all needed nets and values. Don\u2019t mind Pin 5; it’s going to help us in Part 3 of Schematic Basics!<\/em><\/p><\/div>\n

                This brings us to the end of Schematic Basics Part 2, so let’s take a moment to recap the major concepts you learned today:<\/span><\/p>\n