power budget

docs/final-project/integration.md

 # System integration
 
+## USB hub communication
+
 I was unsure how to connect all the robot joints together for a while. Jake Read shows I2C communication using his OSAP library. It would make for a nicely integrated whole, but the joints that have I2C connections might react more slowly than the one in the base, which would be directly connected to the full-speed USB port. So two weeks before the final presentation I ordered a tiny USB hub from a Swiss company called Yoctopuce. When it arrived I was eager to see if it worked and whether it was able to supply enough current to two motors at the same time. So I took my bike over to Hamraborg, bought a USB-C cable, cut it in half and soldered the wires to connectors that I ordered with the USB hub. And here I am running two BLDC motors from one USB port on my laptop (note that this is a special 3A port with a battery charging logo on it):
 
 <video controls width=100%>
       <source src="images/usb_hub_test.mp4" type="video/mp4">
 </video>
 
-Now the whole thing works on a breadboard. Whew!
+Now the whole thing works on a breadboard. Whew!
\ No newline at end of file
+
+## Power budget
+
+A bit later I realized that I hadn't checked whether that one USB-C port could support all the motors and things that I wanted to put in the arm. So I bought another USB-C cable, cut it in half and connected more motors. And here I have three brushless motors and a stepper motor running on one USB-C port at the same time:
+
+<video controls width=100%>
+      <source src="images/power_budget_test.mp4" type="video/mp4">
+</video>
\ No newline at end of file

public/final-project/integration.html

@@ -388,10 +388,48 @@
         
       
       
+        <label class="md-nav__link md-nav__link--active" for="__toc">
+          System integration
+          <span class="md-nav__icon md-icon"></span>
+        </label>
+      
       <a href="integration.html" class="md-nav__link md-nav__link--active">
         System integration
       </a>
       
+        
+
+<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
+  
+  
+  
+    
+  
+  
+    <label class="md-nav__title" for="__toc">
+      <span class="md-nav__icon md-icon"></span>
+      Table of contents
+    </label>
+    <ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
+      
+        <li class="md-nav__item">
+  <a href="#usb-hub-communication" class="md-nav__link">
+    USB hub communication
+  </a>
+  
+</li>
+      
+        <li class="md-nav__item">
+  <a href="#power-budget" class="md-nav__link">
+    Power budget
+  </a>
+  
+</li>
+      
+    </ul>
+  
+</nav>
+      
     </li>
   
 
@@ -724,6 +762,28 @@
     
   
   
+    <label class="md-nav__title" for="__toc">
+      <span class="md-nav__icon md-icon"></span>
+      Table of contents
+    </label>
+    <ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
+      
+        <li class="md-nav__item">
+  <a href="#usb-hub-communication" class="md-nav__link">
+    USB hub communication
+  </a>
+  
+</li>
+      
+        <li class="md-nav__item">
+  <a href="#power-budget" class="md-nav__link">
+    Power budget
+  </a>
+  
+</li>
+      
+    </ul>
+  
 </nav>
                   </div>
                 </div>
@@ -738,12 +798,18 @@
 
 
 <h1 id="system-integration">System integration</h1>
+<h2 id="usb-hub-communication">USB hub communication</h2>
 <p>I was unsure how to connect all the robot joints together for a while. Jake Read shows I2C communication using his OSAP library. It would make for a nicely integrated whole, but the joints that have I2C connections might react more slowly than the one in the base, which would be directly connected to the full-speed USB port. So two weeks before the final presentation I ordered a tiny USB hub from a Swiss company called Yoctopuce. When it arrived I was eager to see if it worked and whether it was able to supply enough current to two motors at the same time. So I took my bike over to Hamraborg, bought a USB-C cable, cut it in half and soldered the wires to connectors that I ordered with the USB hub. And here I am running two BLDC motors from one USB port on my laptop (note that this is a special 3A port with a battery charging logo on it):</p>
 <video controls width=100%>
       <source src="images/usb_hub_test.mp4" type="video/mp4">
 </video>
 
 <p>Now the whole thing works on a breadboard. Whew!</p>
+<h2 id="power-budget">Power budget</h2>
+<p>A bit later I realized that I hadn't checked whether that one USB-C port could support all the motors and things that I wanted to put in the arm. So I bought another USB-C cable, cut it in half and connected more motors. And here I have three brushless motors and a stepper motor running on one USB-C port at the same time:</p>
+<video controls width=100%>
+      <source src="images/power_budget_test.mp4" type="video/mp4">
+</video>