Efficient and Accurate Analog Voltage Measurement Using a Direct Sensor-to-Digital Port Interface for...

Area of Science:

• Electrical Engineering
• Embedded Systems Design
• Sensor Technology

Background:

• Portable sensor systems often rely on microcontrollers or Field-Programmable Gate Arrays (FPGAs) with Analog-to-Digital Converters (ADCs) for sensor interfacing.
• Direct sensor interfacing to digital ports offers an alternative, especially for devices lacking integrated or sufficient ADC channels.
• Existing methods may require complex circuitry or significant memory for look-up tables.

Purpose of the Study:

• To present a technique for directly interfacing analog voltage output sensors to the digital input port of microcontrollers or FPGAs.
• To demonstrate a method that minimizes component count and memory usage in sensor systems.
• To validate the proposed technique through simulations and hardware implementation.

Main Methods:

• Developed a technique using passive components to connect analog sensors to digital input ports.
• The method relies on measuring the duty cycle of a digital square-wave signal generated in response to the analog voltage.
• Validated through LTSpice circuit simulations and implementation on a Gowin GW1NR-9 FPGA.

Main Results:

• A good linear correlation was found between the analog voltage and the measured duty cycle.
• Eliminated the need for memory-intensive look-up tables.
• Achieved a maximum accuracy of 1.09 mV at 9.75 Hz sampling rate, with higher sampling rates (up to 128.31 Hz) yielding slightly reduced accuracy (2.68 mV).

Conclusions:

• The proposed direct interfacing technique is effective for measuring analog voltages using digital ports.
• This method offers a simplified, memory-efficient solution for designing portable sensor systems.
• The technique demonstrates practical feasibility and good performance on low-cost FPGA hardware.