4.c. Pushbuttons

<p>The expansion PCB has designated connection points for three pushbuttons: a push-on/push-off power button connected in parallel with the power button on the 3pi base, a general-purpose pushbutton connected to mbed pin P21 on one side and ground on the other, and a general-purpose pushbutton that is not connected to anything except a set of prototyping pins on each side. This last button can be connected to an arbitrary mbed or Wixel I/O line to create a second user-interface pushbutton.</p> <table class="picture_with_caption center"><tr><td style="max-width: 250px"><a href="https://a.pololu-files.com/picture/0J3630.1200.png?6c700c454fdd72b174d350f735ba6f20" class="noscript-fallback"><img alt="" class="zoomable" data-gallery-pictures="[{&quot;id&quot;:&quot;0J3630&quot;,&quot;caption&quot;:&quot;\u003cp\u003eGeneral-purpose pushbutton on the m3pi expansion PCB.\u003c/p\u003e&quot;,&quot;url_tiny&quot;:&quot;https://a.pololu-files.com/picture/0J3630.98x98.jpg?6c700c454fdd72b174d350f735ba6f20&quot;,&quot;url_medium&quot;:&quot;https://a.pololu-files.com/picture/0J3630.600x480.jpg?6c700c454fdd72b174d350f735ba6f20&quot;,&quot;url_full&quot;:&quot;https://a.pololu-files.com/picture/0J3630.1200.png?6c700c454fdd72b174d350f735ba6f20&quot;,&quot;longest_side&quot;:600}]" data-picture-id="0J3630" data-picture-longest_side="600" src="https://a.pololu-files.com/picture/0J3630.250.jpg?6c700c454fdd72b174d350f735ba6f20" /></a></td><p></tr><tr><th style="max-width: 250px"><p>General-purpose pushbutton on the m3pi expansion PCB.</p></th></tr></table></p> <p>A ground pad is conveniently placed next to the pads connected to the right side of this general-purpose pushbutton, which makes it easy to connect one side of the button to ground.</p>