3.6. Expansion areas

<p>The Romi 32U4 Control Board has several expansion areas (primarily in three groups near the front left and middle and back right edges) that break out all of the general-purpose I/O lines from the ATmega32U4 microcontroller and the Raspberry Pi. The board also provides access to various power inputs, outputs, and control pins, and it makes a few stand-alone buses available to help you make connections. The following diagrams identify the locations of these pins and the hardware associated with them; they are also available as a <a href="/file/0J1261/romi-32u4-control-board-pinout-power.pdf">printable PDF</a> (1MB pdf). For more information about the ATmega32U4 microcontroller and its peripherals, see Atmel&#8217;s ATmega32U4 documentation.</p> <table class="picture_with_caption center wide"><tr><td style="max-width: 600px"><a href="https://a.pololu-files.com/picture/0J7534.1200.jpg?6806f467dc5a7a688274943df76a28d0" class="noscript-fallback"><img alt="" class="wide zoomable" data-gallery-pictures="[{&quot;id&quot;:&quot;0J7534&quot;,&quot;caption&quot;:&quot;\u003cp\u003ePinout diagram of the Romi 32U4 Control Board (ATmega32U4 pinout, peripherals, and board power control).\u003c/p\u003e&quot;,&quot;url_tiny&quot;:&quot;https://a.pololu-files.com/picture/0J7534.98x98.jpg?6806f467dc5a7a688274943df76a28d0&quot;,&quot;url_medium&quot;:&quot;https://a.pololu-files.com/picture/0J7534.600x480.jpg?6806f467dc5a7a688274943df76a28d0&quot;,&quot;url_full&quot;:&quot;https://a.pololu-files.com/picture/0J7534.1200.jpg?6806f467dc5a7a688274943df76a28d0&quot;,&quot;longest_side&quot;:2325}]" data-picture-id="0J7534" data-picture-longest_side="2325" src="https://a.pololu-files.com/picture/0J7534.600.jpg?6806f467dc5a7a688274943df76a28d0" /></a></td><p></tr><tr><th style="max-width: 600px"><p>Pinout diagram of the Romi 32U4 Control Board (ATmega32U4 pinout, peripherals, and board power control).</p></th></tr></table></p> <table class="picture_with_caption center wide"><tr><td style="max-width: 600px"><a href="https://a.pololu-files.com/picture/0J7535.1200.jpg?7eefc37dc5f50c1a281cf469d79ed0a4" class="noscript-fallback"><img alt="" class="wide zoomable" data-gallery-pictures="[{&quot;id&quot;:&quot;0J7535&quot;,&quot;caption&quot;:&quot;\u003cp\u003ePinout diagram of the Romi 32U4 Control Board (Raspberry Pi pinout, peripherals, and level shifters).\u003c/p\u003e&quot;,&quot;url_tiny&quot;:&quot;https://a.pololu-files.com/picture/0J7535.98x98.jpg?7eefc37dc5f50c1a281cf469d79ed0a4&quot;,&quot;url_medium&quot;:&quot;https://a.pololu-files.com/picture/0J7535.600x480.jpg?7eefc37dc5f50c1a281cf469d79ed0a4&quot;,&quot;url_full&quot;:&quot;https://a.pololu-files.com/picture/0J7535.1200.jpg?7eefc37dc5f50c1a281cf469d79ed0a4&quot;,&quot;longest_side&quot;:2430}]" data-picture-id="0J7535" data-picture-longest_side="2430" src="https://a.pololu-files.com/picture/0J7535.600.jpg?7eefc37dc5f50c1a281cf469d79ed0a4" /></a></td><p></tr><tr><th style="max-width: 600px"><p>Pinout diagram of the Romi 32U4 Control Board (Raspberry Pi pinout, peripherals, and level shifters).</p></th></tr></table></p> <table class="picture_with_caption center wide"><tr><td style="max-width: 600px"><a href="https://a.pololu-files.com/picture/0J7536.1200.jpg?2be5c68b31db96f42bbbd2c3384fe754" class="noscript-fallback"><img alt="" class="wide zoomable" data-gallery-pictures="[{&quot;id&quot;:&quot;0J7536&quot;,&quot;caption&quot;:&quot;\u003cp\u003ePower distribution diagram of the Romi 32U4 Control Board.\u003c/p\u003e&quot;,&quot;url_tiny&quot;:&quot;https://a.pololu-files.com/picture/0J7536.98x98.jpg?2be5c68b31db96f42bbbd2c3384fe754&quot;,&quot;url_medium&quot;:&quot;https://a.pololu-files.com/picture/0J7536.600x480.jpg?2be5c68b31db96f42bbbd2c3384fe754&quot;,&quot;url_full&quot;:&quot;https://a.pololu-files.com/picture/0J7536.1200.jpg?2be5c68b31db96f42bbbd2c3384fe754&quot;,&quot;longest_side&quot;:1440}]" data-picture-id="0J7536" data-picture-longest_side="1440" src="https://a.pololu-files.com/picture/0J7536.600.jpg?2be5c68b31db96f42bbbd2c3384fe754" /></a></td><p></tr><tr><th style="max-width: 600px"><p>Power distribution diagram of the Romi 32U4 Control Board.</p></th></tr></table></p>