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USB Connector Comparison

Run the USB Connector Comparison MicroSim fullscreen

About This MicroSim

Two connectors, three differences that show up on a club bench.

Which way up. Press Flip the USB-A and watch the plug turn over: the contacts move from the bottom of the shell to the top, and now they do not line up with the socket. The tongue inside a USB-A socket is on one side only, and the matching gap in the plug has to face it. Flip the USB-C and nothing changes — the shell is symmetrical and the contacts are mirrored top and bottom, so there is no wrong way up.

That sounds like a small convenience and is not. On a bench with twenty students plugging things in, "it's upside down" is a whole category of failure that simply disappears with USB-C.

Which end of the cable. A USB-A plug is nearly always the host end — the computer or the hub. USB-C turns up at both ends, and which one is the host is negotiated electrically rather than fixed by the shape.

How much power. A plain USB-A port gives 5 V and somewhere between half an amp and a couple of amps: fine for a Pico or a sensor board, not enough for motors. USB-C can carry up to 5 A, and with Power Delivery can negotiate higher voltages entirely. One caution worth passing on: a cheap USB-C cable may only be rated for the basic 3 A and looks identical to one that is not.

How to Use

  • Press Flip the USB-A. Watch the gold contacts move from the bottom of the shell to the top — that is the asymmetry, and it is why the plug no longer fits.
  • Press Flip the USB-C and compare. Nothing moves that matters.
  • Click any numbered point on either connector for that difference in detail.
  • Reset puts both plugs the right way up and clears the selection.

Lesson Plan

Bloom level: Analyze (L4) -- differentiate

Learning objective: Given a USB-A and a USB-C connector drawn side by side, the learner differentiates the two by shape, orientation, and typical power/data capability.

Before the sim (5 min). Empty the club's cable box onto a table and ask people to sort it. The sorting criteria they invent are usually about the shape, which is the right instinct.

With the sim (10 min). Run both flips. Then go back to the cable pile and have people predict, for each cable, which end goes into the laptop.

After the sim (15 min). Make the purchasing decision as a group: what does the club buy next, and why? "USB-C because nobody can plug it in wrong" is a real argument with a real time cost attached to the alternative.

Check for understanding. Ask: "Why can't you charge a laptop from a USB-A port?" Not enough power — 5 V at a couple of amps is around 10 watts against the 60 watts a laptop wants, which is what Power Delivery over USB-C exists to supply.

Embedding This MicroSim

Paste this into any page of the book, adjusting the relative path to docs/sims/ for the page's depth:

<iframe src="../../sims/usb-connector-comparison/main.html" width="100%" height="542" scrolling="no"></iframe>

Specification

The full specification below is extracted from Chapter 18: Robots, USB Basics, and Electronics Workshop Skills.

Type: infographic
**sim-id:** usb-connector-comparison<br/>
**Library:** p5.js<br/>
**Status:** Specified

Purpose: Let a learner compare the two connector shapes side by side and click each labeled feature to see why it matters for a club's day-to-day cable choices.

Bloom Taxonomy: Analyze (L4)
Bloom Taxonomy Verb: differentiate

Learning objective: Given a USB-A and a USB-C connector drawn side by side, the learner differentiates the two by shape, orientation, and typical power/data capability.

Visual elements: Two large scale drawings side by side — a rectangular USB-A plug on the left, an oval USB-C plug on the right — each with 3 labeled callout points (shape/orientation, typical host device, typical power delivery).

Interactive controls: Click any callout point on either connector to open an infobox with that feature's explanation; a "Flip It" button under each drawing that visually rotates the plug 180 degrees to show whether it still fits.

Default parameters: Both connectors shown unselected, right-side up.

Behavior: Clicking a callout (e.g., "Reversible") opens an infobox pulling its definition from the chapter glossary; clicking "Flip It" animates the rotation and displays a green checkmark (USB-C, always fits) or a red X (USB-A, only fits one way).

Implementation notes: p5.js canvas with two vector-drawn connector shapes; click-region detection for callouts; a simple rotation animation triggered by the Flip It buttons; canvas resizes responsively to container width.

References