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Commit 2a998df5 authored by Svavar Konradsson's avatar Svavar Konradsson
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power budget

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# System integration # 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): 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%> <video controls width=100%>
<source src="images/usb_hub_test.mp4" type="video/mp4"> <source src="images/usb_hub_test.mp4" type="video/mp4">
</video> </video>
Now the whole thing works on a breadboard. Whew! Now the whole thing works on a breadboard. Whew!
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## 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
File added
...@@ -388,10 +388,48 @@ ...@@ -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"> <a href="integration.html" class="md-nav__link md-nav__link--active">
System integration System integration
</a> </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> </li>
...@@ -724,6 +762,28 @@ ...@@ -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> </nav>
</div> </div>
</div> </div>
...@@ -738,12 +798,18 @@ ...@@ -738,12 +798,18 @@
<h1 id="system-integration">System integration</h1> <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> <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%> <video controls width=100%>
<source src="images/usb_hub_test.mp4" type="video/mp4"> <source src="images/usb_hub_test.mp4" type="video/mp4">
</video> </video>
<p>Now the whole thing works on a breadboard. Whew!</p> <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>
......
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