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Cable Diagnostic System Hero Image
Electronics + Product Development
A compact electronic diagnostic system developed to provide a user-friendly way to test different cable standards through an integrated touchscreen interface.
Type
Cable Diagnostic System
Period
High School
Controller
ATmega2560
Interface
2.8" TFT Colour LCD
Development
Electronics + PCB
CAD + Embedded Software
Project Context
Completed during high school as part of the Advanced Computer Engineering School program at Royal St. George's College. The project began as two separate devices before development shifted toward a single compact cable diagnostic system.
References
01
The project was developed to create a user-friendly way to test different cables within one compact electronic device.
The main focal point of the system is a 2.8-inch TFT colour LCD display used to create a clean and minimal user interface. An ATmega2560 breakout board was selected for its pin-to-form-factor ratio and provides the controller for the device.
Prototyping was completed in three stages: breadboard assembly, PCB development, and CAD. These stages brought the cable-testing electronics, interface, battery system, connector breakout boards, and enclosure into one system.
02
The diagnostic system tests continuity from one end of a cable to the other, allowing the connections within Ethernet and USB cables to be displayed through the interface.
01 / Ethernet
Ethernet cables use RJ45 connectors and contain eight conductors crimped to a specific pinout. The Cable Diagnostic System displays continuity from end to end across the cable.
02 / USB
USB cables use four primary connections: VBUS, GBUS, D+, and D-. The system tests continuity across these connections to determine how the cable is configured.
03 / Cable Type
A functioning USB data cable displays four connected lines between the ports. A power-delivery-only cable displays two, allowing otherwise unmarked cables to be identified.
Control Electronics
Qty.
Rugged Metal Pushbutton
1
ATmega2560 Breakout Board
1
2.8" TFT Colour LCD Display
1
RJ45 Breakout Board
2
USB 3.0 Breakout Board
1
USB B Breakout Board
1
Mini USB Breakout Board
1
USB C Breakout Board
2
3.7 V 1200mAh LIPO
2
LIPO Battery Charger
1
Battery Management System
2
Inductive Charging Coil
2
Custom PCB
1
Pin Headers
Assorted
Wires
Assorted
03
A 2.8-inch TFT colour LCD with a resistive touchscreen forms the central interface of the diagnostic system.
The display contains 76,800 pixels and a four-LED white backlight. An integrated controller with RAM buffering reduces the processing load placed on the microcontroller. The display operates in 8-bit mode using eight digital data lines, five control lines, and four touch lines.
The resistive touchscreen was calibrated using X and Y offsets. Custom graphics were created for each connector, allowing the touchscreen to function as the primary user-facing interface for the cable tester.
Touchscreen Interface + Connector Graphics
TFT interface, touchscreen calibration, and custom graphics
Cable Diagnostic System
04
The electronics were developed around an ATmega2560 breakout board, battery-management hardware, connector breakout boards, and an inductive charging system.
Controller
The ATmega2560 breakout board was selected to reduce PCB complexity while maintaining a high pin-to-form-factor ratio. The board provides capabilities similar to a traditional Arduino Mega within a smaller form factor.
Power System
The system uses two 3.7 V 1200mAh LiPo batteries, a LiPo battery charger, and two battery-management systems. Battery and power operation was tested during the breadboard stage.
Inductive Charging
Two inductive charging coils transfer power through a magnetic field between the transmitter and receiver. The coils are limited to a maximum of 5 V at 0.5 A depending on input power.
Programming
LEDs and the serial programming chip were removed from the PCB to reduce unnecessary power consumption. An external ribbon cable connector was added for ICSP programming.
Breadboard Assembly
Initial electronics and power-system prototype
Integrated Electronics
Controller, connector interfaces, and charging electronics
05
Development progressed from a breadboard prototype through two PCB revisions as the electronics were reduced into a compact system.
Breadboard
Breakout boards were soldered to jumper wires and connected to an Arduino Mega. The battery and power system were also tested before development moved to the PCB.
PCB V1
Due to ATmega2560 availability and pricing, the first PCB revision attempted to transfer the MCU and USB-B port from donor boards. Damage to the MCU corner pins made this approach unusable.
PCB V2
The second revision used a more compact form factor and an ATmega2560 breakout board to reduce the number of supporting components required on the PCB.
Screen Backpack
The second PCB was manufactured to the exact dimensions of the screen, creating a compact backpack with a direct fit behind the display.
PCB Development — Breadboard / V1 / V2
Development from breadboard assembly to compact screen-mounted PCB
Cable Diagnostic System
06
The CAD was divided into four sections: the top, middle, bottom, and wireless charging base.
Top
The top lid houses the screen, PCB, MCU, and supporting components. Heated inserts secure the screen and PCB using standoffs.
Middle
The middle section secures the ports and rear power button. It also incorporates cable management and support for the battery-management system.
Bottom
The bottom section houses the inductive charging coil, charging driver, and two LiPo batteries.
Charging Base
The fourth section is the wireless charging base. It houses the transmitter inductive coil and a USB-C breakout board for power input.
Enclosure Development
Top, middle, and bottom enclosure sections
Wireless Charging Base
Integrated inductive charging base
07
The enclosure components were designed around the tightly packaged electronics and 3D printed in PLA on a Creality Ender 3-Pro.
All four parts were printed in PLA. The enclosure sections use a ledge design that allows the parts to snap together, creating a screwless appearance from the outside.
The internal design was developed around extremely compact component placement. In some areas, only 0.5 mm of tolerance remained between breakout boards in order to reduce the overall size of the device.
08
The completed Cable Diagnostic System combined custom electronics, PCB development, embedded programming, touchscreen interaction, battery power, and a compact 3D-printed enclosure.
The final system uses custom graphics for each connector and touchscreen input to create a user-friendly interface for testing cables. The project also developed register level programming and touchscreen calibration skills.
The finished cable tester continued to be used after the project, particularly when identifying USB power-delivery cables for charging electronics.
Final Cable Diagnostic System
Completed cable tester and wireless charging system
Cable Diagnostic System