Toward non-CPU activity in low-power MCU-Based measurement systems

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis article evaluates the benefits of having peripheral-triggered peripherals in a microcontroller unit (MCU) intended for low-power sensor applications. In such an architecture, the functionality is moved from the central processing unit (CPU) to the peripherals so that a peripheral is able to trigger another peripheral with non-CPU intervention. For the sensor data logging application under study, both energy consumption and measuring time are reduced by a factor of 2 with respect to the case of applying an interrupt-based approach that requires the CPU intervention.Peer ReviewedPostprint (author's final draft

A microcontroller-based interface circuit for non-linear resistive sensors

This article proposes a circuit based on a microcontroller unit (MCU) for the direct measurement and linearization of non-linear resistive sensors, such as thermistors. The measurement relies on an embedded digital timer and does not require (either embedded or external) operational amplifiers or an analog-to-digital converter, thus resulting in a low-cost, low-power design solution. The circuit includes a known resistor with a twofold function: it is a reference for circuit auto-calibration purposes, and it is in parallel with the non-linear resistive sensor for linearization purposes.Postprint (updated version

Rail-to-Rail Timer-Based Demodulator for AM Sensor Signals

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper proposes a novel timer-based demodulator for low-frequency amplitude-modulated (AM) sensor signals with a rail-to-rail operating range. The demodulator extracts the amplitude of the AM signal by measuring the period of a reference signal that is altered by the AM signal itself, as already suggested in a previous paper. The rail-to-rail operation, which is the main contribution of the novel circuit, is achieved by simply but cleverly incorporating a multiplexer that enables the comparison between the two signals (reference and AM) just at the beginning and at the end of the period measurement. This new topology offers an operating range that is up to more than four times wider than that reported in the literature. The input-output characteristic in such a wider operating range is not linear, but it can be accurately modeled by a second-degree polynomial.Peer ReviewedPostprint (author's final draft

Plan Prototype Microcontroller based 30 Meter Running Speed Test Equipment

This research aims to produce a 30 meter running speed equipment product athlete North Sumatra which is microcontroller based. It is hoped that this research will be able to overcome the difficulties faced by testers which have so far been carried out manually so that they are effective and effective objectivity The results of this test still cannot be categorized as accurate. This research uses an approach of research and development with the Borg and Gall model which is divided into three stages. The research stages are; (1) Pre-development stage, which one At this stage, a needs analysis is carried out through survey level of tool requirements for users, preparation instrument and consultation to experts. (2) Development stage develop products running speed 30 meters starting from developing initial product manuscripts (manual books), designing digital tools, trials small group, stage I improvement, trials large group, phase II improvement, mass production. (3) Evaluation stage implementation of product results and dissemination product. The results of the analysis from the trial I obtained an average value implementation of Microcontroller-Based 30 Meter Running Speed ​​Test Equipment based on data obtained for the answer "Yes" with a percentage of 81.38% and "No" with a percentage of 18.62%. The results of the analysis of trial II obtained an average value implementation plan prototype digital step frequency measuring test tool based on data obtained for the answer "Yes" with a percentage of 86.08% and "No" with a percentage of 13.92%. The conclusion in this research is that the test tool developed is valid because the calculation uses a digital system

Demodulating AM square signals via a digital timer for sensor applications

This paper evaluates theoretically and experimentally the performance of a timer-based demodulator applied to low-frequency amplitude-modulated (AM) square signals coming from sensor circuits. The demodulator extracts the amplitude of the AM square signal by measuring the period of a reference triangular signal that is altered by the AM signal itself, as already suggested in a previous paper but for AM sinusoidal signals.Postprint (published version

Direct interface circuits for resistive sensors affected by lead wire resistances

This article proposes two novel circuits for the digital readout of resistive sensors with parasitic series resistances caused by the lead wire needed to connect remote sensors. Both circuits are based on so-called direct interface circuits (DICs). These circuits perform a resistance-to-time-to-digital conversion by adding some external components to a digital processors (DP). The new circuits are very simple since they only use a capacitor and two or three resistors, depending on the proposal. A single discharging of the capacitor provides two or three time measurements to estimate the resistance of the sensor, eliminating the influence of lead wire resistances. Using a single discharging process simultaneously reduces error sources, measurement time, and energy consumption. A circuit that uses an FPGA as DP to estimate resistances corresponding to several thermal sensors presents systematic errors below 0.15% or 0.12%, depending on the proposal, for a maximum measurement time of 1.09 ms.This work was supported by the Spanish Government under contract PID2021-125091OB-I00. Funding for open access charge: Universidad de Málaga / CBUA

Two proposals to simplify resistive sensor readout based on Resistance-to-Time-to-Digital conversion

Direct Interface Circuits (DICs) are simple circuits used in readouts for all types of sensors. For resistive sensors, all DICs perform a resistance-to-time-to-digital conversion using just the sensor, some calibration resistors, one or two capacitors, and a Digital Processor. These circuits require a variable number of charging and discharging cycles of a capacitor to estimate the sensor resistance, Rx, increasing both acquisition time and power consumption. This paper presents two resistive DICs capable of estimating Rx by means of a single charging-discharging process, simplifying the readout process. Furthermore, this is achieved without increasing hardware requirements. Only two time measurements are used to obtain Rx. Despite the simplicity of the new circuits, the experimental results show that relative errors of estimating Rx can be below 0.8 %, and this in a wide range of resistances of over 40 dB. Moreover, acquisition time and energy consumption can be reduced by up to 75 %.Funding for open access charge: Universidad de Málaga / CBUA. This work was supported by the Spanish Government under contract PID2021-125091OB-I0

Analysis of a direct microcontroller interface for capacitively coupled resistive sensors

© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. DOI:10.1109/TIM.2020.3034969A novel approach to directly interface a capacitively coupled resistive sensor to a microcontroller is presented in this article. The existing measurement schemes for such sensors are complex. In addition, the coupling capacitance often also holds important data. The proposed simple measurement system, for such series RC sensors, is capable of measuring both the resistance and the coupling capacitance. A detailed analysis on the effect of the nonidealities on the resistance measurement showed that it is independent of the accuracy of the charging capacitor, supply voltage, and preset threshold voltagePostprint (published version

A tutorial on thermal sensors in the 200th anniversary of the seebeck effect

Two noteworthy events associated to the physics of thermal sensors were demonstrated and announced in 1821, exactly two hundred years ago. The first event was the Seebeck effect, which led to the development of thermocouples. The second was the study of the thermal dependence of the resistivity of pure metals, which led to the design of resistance temperature detectors (RTD).Postprint (updated version