Here is our USB cable tester board.

USB Cable Tester – User’s Manual

🧭 Introduction

The USB Cable Tester is a diagnostic tool designed to verify internal wiring of various USB cables with minimum length of 12 inches or 30 centimeters. This manual provides instructions for use of the tester.

🔍 Overview

Power Source: CR2032 Lithium Cell (3V).

Purpose: Test pin continuity and identify passive USB cables.

🔌 Connector combinations supported:

A-side:

• Type-C
• Type-A / Type-A Super Speed

B-Side:

• Type-C
• Type-B / Type-B Super Speed
• Micro-B / Micro-B Super Speed
• Mini-B
• Lightning

It passively illuminates LEDs showing which signals (power, data, configuration, shield) are connected between the cable ends.

Board Layout

– Pin mapping LED matrices
– Label overlays for signal identification

– Test points for a USB cable pin to pin continuity tests

⚠️ WARNING: Before continuity tests with a multimeter the battery (CR2032) must be removed!

⚠️ Safety Warnings

• Use only with unpowered cables! DO NOT connect this tester to a USB charger, PC, or live USB host. Connecting the tester to a charger or active USB port may damage the device or cause injury.
• Keep out of reach of children. It is not a toy.
• Handle with Care: Avoid short-circuiting pins or exposing the board to moisture.
• The board is not designed to carry power or signals – it’s a passive tester.

📐 How to Use and Interpret Results

1. Ensure the tester is powered by the CR2032 battery.
2. Testing a Cable:
3. Select the appropriate USB ports on the tester matching your cable type (e.g., Type-C to Type-C).
4. Connect one end of the cable to a port on Side A.
5. Connect the other end to the corresponding port on Side B.
6. Interpreting Results:
7. Visually inspect the LED indicators. Check for consistent pin connections (e.g., Power: VBUS, GND. Data: D+, D-…).
8. Use the reference matrix (the tester board bottom side) to identify the cable.
9. Once testing is complete, unplug both ends of the USB cable to preserve battery life.

💡 Understanding LED Indicators

• Each LED indicates the presence of a connected signal path through the cable, except for the configuration lines CC1 and CC2.
  • LED ON = continuity exists on that line
  • LED OFF = no connection on that line
• The CC1 and CC2 LEDs indicate the presence of pull-up resistors (Rp) built into the cable on the Downstream Facing Port (DFP) – typically the host:
  • 56 kΩ (USB 2.0: 500mA, USB 3.x: 900mA)
  • 22 kΩ (1.5A)
  • 10 kΩ (3.0A)

The Rp resistor defines the advertised current to the Upstream Facing Port (UFP) – typically the device – which uses a 5.1 kΩ pull-down resistor (Rd). This combination forms voltage levels of approximately 0.66 V, 1.1 V or 1.7 V from a 5 V DC source.

• CC1 and CC2 connections in the Type-C to Type-C cables, as well as pin to pin shorts are not indicated by LEDs. These can be tested using a multimeter in continuity test mode.

⚠️ Refer to the battery removal warning mentioned above before testing.

📘 Signal Reference Guide

Signal	Description
VBUS	Bus power line
GND	Ground for power return
D+, D-	USB 2.0 data lines (One – unshielded twisted pair)
TX1+/-, RX1+/-, TX2+/-, RX2+/-	USB 3.x SuperSpeed lines (Four – shielded differential pairs)
CC1 / CC2	Configuration channels (USB-PD)
SBU1 / SBU2	Sideband use (USB-C)
Shield	Cable external braid

The USB Type-C connector supports multiple standards, each with distinct signal configurations. Use the tester to verify the following essential signals:

USB 2.0 Data Cable:

Essential Signals: D+/- (Data +/-), VBUS (Power), GND (Ground).

Description: Supports data transfer up to 480 Mbps and power delivery up to 3A. Only uses two differential data pairs (D+ and D-).

USB 3.x Data Cable:

Essential Signals: USB 2.0 data cable signals plus TX+/-, RX+/- (SuperSpeed pairs).

Description: Supports data transfer up to 10 Gbps (USB 3.2 Gen 2) with additional SuperSpeed differential pairs.

USB-PD (Power Delivery) Cable:

Essential Signals: VBUS, GND, CC1/CC2 (Configuration Channels).

Description: Designed for power delivery up to 100W (20V, 5A) with dynamic voltage negotiation.

USB4 / Thunderbolt Cable:

Essential Signals: USB 3.x cable signals plus USB-PD signals plus TX1+/-, RX1+/-, TX2+/-, RX2+/- (Thunderbolt lanes), SBU1/2 (Sideband use).

Description: Supports data transfer up to 80 Gbps, video output, and power delivery. Verify all high-speed pairs and power lines.

📝 Notes

– Cables without shielding may still work but may fail EMC/EMI compliance requirements.
– Not all USB-C cables support all signals

🛠️ Troubleshooting

Issue	Possible Cause	Solution
No LEDs light up	Battery dead or reversed	Replace or flip the battery
Some expected LEDs are off	Cable missing lines or is defective	Try a known-good cable
LEDs dim or flickering	Bad a USB port contacts	Try a known-good cable

📊 Technical Specifications

– Power Source: CR2032 coin cell battery

– Maximum Battery Current: 8 mA
– Compatibility: USB-A/B/C, Micro/Mini-B, Lightning
– Test method: Passive continuity via LED
– Minimum Supported Cable Length: 25 cm

– Dimensions: 100mm x 100mm