{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T01:14:34Z","timestamp":1771550074830,"version":"3.50.1"},"reference-count":25,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2017,5,18]],"date-time":"2017-05-18T00:00:00Z","timestamp":1495065600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper evaluates the performance of direct interface circuits (DIC), where the sensor is directly connected to a microcontroller, when a resistive sensor subjected to dynamic changes is measured. The theoretical analysis provides guidelines for the selection of the components taking into account both the desired resolution and the bandwidth of the input signal. Such an analysis reveals that there is a trade-off between the sampling frequency and the resolution of the measurement, and this depends on the selected value of the capacitor that forms the RC circuit together with the sensor resistance. This performance is then experimentally proved with a DIC measuring a magnetoresistive sensor exposed to a magnetic field of different frequencies, amplitudes, and waveforms. A sinusoidal magnetic field up to 1 kHz can be monitored with a resolution of eight bits and a sampling frequency of around 10 kSa\/s. If a higher resolution is desired, the sampling frequency has to be lower, thus limiting the bandwidth of the dynamic signal under measurement. The DIC is also applied to measure an electrocardiogram-type signal and its QRS complex is well identified, which enables the estimation, for instance, of the heart rate.<\/jats:p>","DOI":"10.3390\/s17051150","type":"journal-article","created":{"date-parts":[[2017,5,23]],"date-time":"2017-05-23T01:47:33Z","timestamp":1495504053000},"page":"1150","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Measuring Dynamic Signals with Direct Sensor-to-Microcontroller Interfaces Applied to a Magnetoresistive Sensor"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1739-3317","authenticated-orcid":false,"given":"Ernesto","family":"Sifuentes","sequence":"first","affiliation":[{"name":"Department of Computer and Electrical Engineering, Universidad Aut\u00f3noma de Ciudad Ju\u00e1rez (UACJ), 32310 Ciudad Ju\u00e1rez, Mexico"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5148-4517","authenticated-orcid":false,"given":"Rafael","family":"Gonzalez-Landaeta","sequence":"additional","affiliation":[{"name":"Department of Computer and Electrical Engineering, Universidad Aut\u00f3noma de Ciudad Ju\u00e1rez (UACJ), 32310 Ciudad Ju\u00e1rez, Mexico"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3592-1198","authenticated-orcid":false,"given":"Juan","family":"Cota-Ruiz","sequence":"additional","affiliation":[{"name":"Department of Computer and Electrical Engineering, Universidad Aut\u00f3noma de Ciudad Ju\u00e1rez (UACJ), 32310 Ciudad Ju\u00e1rez, Mexico"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1653-0519","authenticated-orcid":false,"given":"Ferran","family":"Reverter","sequence":"additional","affiliation":[{"name":"e-CAT Research Group, Department of Electronic Engineering, Universitat Polit\u00e8cnica de Catalunya (UPC)\u2014BarcelonaTech, C\/Esteve Terradas 7, C4, 08860 Castelldefels, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2017,5,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1016\/j.sna.2005.01.010","article-title":"Accuracy and resolution of direct resistive sensor-to-microcontroller interfaces","volume":"121","author":"Reverter","year":"2005","journal-title":"Sens. Actuators A Phys."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3405","DOI":"10.1109\/TIM.2009.2017651","article-title":"Interfacing differential resistive sensors to microcontrollers: A direct approach","volume":"58","author":"Reverter","year":"2009","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1016\/j.sna.2008.05.023","article-title":"Direct interface circuit to linearise resistive sensor bridges","volume":"147","author":"Sifuentes","year":"2008","journal-title":"Sens. Actuators A Phys."},{"key":"ref_4","unstructured":"Ponnalagu, R.N., George, B., and Kumar, V.J. (2014, January 2\u20134). A microcontroller sensor interface suitable for resistive sensors with large lead resistance. Proceedings of the 8th International Conference Sensing Technology, Liverpool, UK."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1016\/j.sna.2007.11.018","article-title":"Direct interface circuit for capacitive humidity sensors","volume":"143","author":"Reverter","year":"2008","journal-title":"Sens. Actuators A Phys."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2763","DOI":"10.1109\/TIM.2009.2036500","article-title":"Interfacing differential capacitive sensors to microcontrollers: A direct approach","volume":"59","author":"Reverter","year":"2010","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"545","DOI":"10.1109\/TIM.2011.2164860","article-title":"Low-cost capacitive humidity sensor for application within flexible RFID labels based on microcontroller systems","volume":"61","author":"Sogorb","year":"2012","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/j.sna.2014.01.040","article-title":"A self-calibration water level measurement using an interdigital capacitive sensor","volume":"209","author":"Chetpattananondh","year":"2014","journal-title":"Sens. Actuators A Phys."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1016\/j.sna.2015.01.017","article-title":"Direct inductive sensor-to-microcontroller interface circuit","volume":"224","author":"Kokolanski","year":"2015","journal-title":"Sens. Actuators A Phys."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Ramadoss, N., and George, B. (2015, January 11\u201314). A simple microcontroller based digitizer for differential inductive sensors. Proceedings of the IEEE International Instrumentation Measurement Technology Conference, Pisa, Italy.","DOI":"10.1109\/I2MTC.2015.7151256"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1016\/j.sna.2012.02.048","article-title":"Direct analog-to-microcontroller interfacing","volume":"179","author":"Bengtsson","year":"2012","journal-title":"Sens. Actuators A Phys."},{"key":"ref_12","first-page":"38","article-title":"Microcontroller based e-nose for gas classification without using ADC","volume":"202","author":"Dutta","year":"2016","journal-title":"Sens. Transducers"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"265","DOI":"10.3390\/jlpea2040265","article-title":"The art of directly interfacing sensors to microcontrollers","volume":"2","author":"Reverter","year":"2012","journal-title":"J. Low Power Electron. Appl."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Oballe-Peinado, O., Vidal-Verd\u00fa, F., S\u00e1nchez-Dur\u00e1n, J.A., Castellanos-Ramos, J., and Hidalgo-L\u00f3pez, J.A. (2016). Accuracy and resolution analysis of a direct resistive sensor array to FPGA interface. Sensors, 16.","DOI":"10.3390\/s16020181"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"31762","DOI":"10.3390\/s151229878","article-title":"Smart capture modules for direct sensor-to-FPGA interfaces","volume":"15","year":"2015","journal-title":"Sensors"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"503","DOI":"10.1109\/TIM.2012.2216473","article-title":"Power consumption in direct interface circuits","volume":"62","author":"Reverter","year":"2013","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Henzler, S. (2010). Time-to-Digital Converters, Springer.","DOI":"10.1007\/978-90-481-8628-0"},{"key":"ref_18","unstructured":"Bengtsson, L. (2013). Embedded Measurement Systems. [Ph.D. Thesis, Department of Physics, University of Gothenburg]."},{"key":"ref_19","first-page":"1","article-title":"Respiratory rate detection by a time-based measurement system","volume":"37","author":"Sifuentes","year":"2016","journal-title":"Rev. Mex. Ing. Biom\u00e9d."},{"key":"ref_20","unstructured":"Hoeschele, D.F. (1994). Analog-To-Digital and Digital-To-Analog Conversion Techniques, John Wiley & Sons."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Westra, J.R., Verhoeven, C.J.M., and van Roermund, A.H.M. (1999). Oscillators and Oscillator Systems. Classification, Analysis and Synthesis, Kluwer Academic Publishers.","DOI":"10.1007\/978-1-4757-6117-7"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/j.sna.2004.08.027","article-title":"Analysis of power supply interference effects on quasi-digital sensors","volume":"119","author":"Reverter","year":"2005","journal-title":"Sens. Actuators A Phys."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2157","DOI":"10.1088\/0957-0233\/15\/10\/028","article-title":"Effective number of resolution bits in direct sensor-to-microcontroller interfaces","volume":"15","author":"Reverter","year":"2004","journal-title":"Meas. Sci. Technol."},{"key":"ref_24","unstructured":"ANSI\/AAMI EC13: 2002\/(R2007) (2002). Cardiac Monitors, Heart Rate Meters, and Alarms, ANSI Standard."},{"key":"ref_25","unstructured":"Webster, J. (2009). Medical Instrumentation: Application and Design, John Wiley & Sons."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/5\/1150\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:36:11Z","timestamp":1760207771000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/5\/1150"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,5,18]]},"references-count":25,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2017,5]]}},"alternative-id":["s17051150"],"URL":"https:\/\/doi.org\/10.3390\/s17051150","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,5,18]]}}}