Our campaign page: Crowd Supply USB VSense

hackster.io review of USB VSense

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Introduction

Welcome to our build log, we would like you to join us on our journey  in designing a USB voltage indicator. You will discover the complexity involved, the many hills and sometimes, mountains we had to climb to arrive at our USBVSense. IT was a long journey, but a wonderful voyage of discovery from the very start. Welcome  and enjoy the ride

Features & Specifications

  • Fully capable of the latest USB PD EPR specifications (48 V, 5 A, 240 W)
  • A wide operational and measurement range of 4.5 V to 51 V
  • Individual color-coded indicators for each fixed voltage level:
    • 5 V (red)
    • 9 V (orange)
    • 12 V (yellow)
    • 15 V (green)
    • 20 V (lime)
    • 28 V (blue)
    • 36 V (purple)
    • 48 V (white)
  • Distinct alerts show > 5% and > 10% deviations from the fixed voltages. This feature is also helpful in approximating PPS voltages
  • Passthrough for USB 2.0 data, CC, and SBUS lines
  • Ultra-low power consumption, less than 6 mA of current drawn by the device (absolute maximum under regular operation)
  • ATtiny 406’s 10-bit ADC with 4.3 V internal voltage reference provides stable measurements of up to 22 mV resolution for voltages below 20 V and 49 mV for voltages between 20 V and 51 V
  • Stacked PCB construction with high-quality parts built to last:
    • Automotive grade LDO from Microchip (+70 V absolute max input voltage with ESD protection)
    • Kingbright low-current LEDs
    • JAE USB Type-C connectors rated for 48 V and 5 A
  • Dimensions: 56 x 18.5 x 5.6 mm (2.28 x 0.73 x 0.22 in)

The following table demonstrates the range of lights and flashing patterns and what they mean:

Voltage RangeState of Annunciators
Lower than 10% of 5 V (E.g. 4.4 V)5 V (red) rapidly blinking
Lower than 5% of 5 V but higher than 10% (E.g., 4.7 V)5 V (red) slowly blinking
Higher than 5% of 12 V but lower than 10% (E.g., 13 V)12 V (yellow) steady and 15 V (green) slowly blinking
Higher than 10% of 12 V but lower than average of 12 V and 15 V (E.g., 13.4 V)12 V (yellow) steady and 15 V (green) rapidly blinking
Within 5% of 15 V (E.g. 15.1 V)15 V (green) steady
Lower than 10% of 20 V but higher than average of 15 V and 20 V (E.g. 18.5 V)15 V (green) rapidly blinking and 20 V (lime) steady
Lower than 5% of 20 V but higher than 10% (E.g. 19.5 V)15 V (green) slowly blinking and 20 V (lime) steady
Above measuring capability (E.g. 52 V)48 V (white) rapidly blinking

Design Files: 

We intend to make USB VSense fully open-source as soon as possible, we intend on publishing all the design files, including KiCAD project files, MPLABX project files, parts list, assembly instructions, etc. (Anything that is needed to manufacture and or customize USB VSense), as soon as we are done with our Crowd Supply campaign.

Current Status

Small production run of 32 units has been completed with satisfactory results


Design Vision

The Design vision of USB VSense directly stems from the mission statement of Meticulous Technologies, which is, if we were to summarize it in one sentence, is to "Deliver top-quality electronics, which meaningfully adds value to the lives of those who use it, and freely share knowledge while in the process of doing so", thjat's why we intend all current and future projects to be fully open-source. 

Currently, there is no shortage of USB meters in the market with endless lists of features, therefore, we conceived of a device that focused on only essential features for USB power diagnostics while still being useful to most users. We stuck to the keep-it-simple design principle as much as possible throughout the design process. What we would lose in terms of features we hoped to gain in terms of ergonomics, compactness, aesthetics, manufacturability, durability, and robustness, we also aimed for the device to be as easily as possible customizable by the user.

The very first decision we made was to not use a display to display the USB voltage, instead we opted for simple color-coded LED based indicators...

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