{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,27]],"date-time":"2025-10-27T21:06:28Z","timestamp":1761599188575,"version":"build-2065373602"},"reference-count":37,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2019,9,7]],"date-time":"2019-09-07T00:00:00Z","timestamp":1567814400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["TEC2015-67642-R"],"award-info":[{"award-number":["TEC2015-67642-R"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100009473","name":"Universidad de M\u00e1laga","doi-asserted-by":"publisher","award":["Plan Propio 2018"],"award-info":[{"award-number":["Plan Propio 2018"]}],"id":[{"id":"10.13039\/100009473","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A simple method to measure the resistance of a sensor and convert it into digital information in a programmable digital device is by using a direct interface circuit. This type of circuit deduces the value of the resistor based on the discharge time through it for a capacitor of a known value. Moreover, the discharge times of this capacitor should be measured through one or two resistors with known values in order to ensure that the estimate is not dependent on certain parameters that change with time, temperature, or aging. This can slow down the conversion speed, especially for high resistance values. To overcome this problem, we propose a modified process in which part of the discharge, which was previously performed through the resistive sensor only, is only conducted with the smallest calibration resistor. Two variants of this operation method, which differ in the reduction of the total time necessary for evaluation and in the uncertainty of the measurements, are presented. Experiments carried out with a field programmable gate array (FPGA); using these methodologies achieved reductions in the resistance conversion time of up to 55%. These reductions may imply an increase in the uncertainty of the measurements; however, the tests carried out show that with a suitable choice of parameters, the increases in uncertainty, and therefore errors, may be negligible compared to the direct interface circuits described in the literature.<\/jats:p>","DOI":"10.3390\/s19183871","type":"journal-article","created":{"date-parts":[[2019,9,9]],"date-time":"2019-09-09T04:12:40Z","timestamp":1568002360000},"page":"3871","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Fast Calibration Methods for Resistive Sensor Readout Based on Direct Interface Circuits"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9505-9141","authenticated-orcid":false,"given":"Jos\u00e9 A.","family":"Hidalgo-L\u00f3pez","sequence":"first","affiliation":[{"name":"Departamento de Electr\u00f3nica, Universidad de M\u00e1laga, Andaluc\u00eda Tech, Campus de Teatinos, 29071 M\u00e1laga, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jes\u00fas A.","family":"Bot\u00edn-C\u00f3rdoba","sequence":"additional","affiliation":[{"name":"Departamento de Electr\u00f3nica, Universidad de M\u00e1laga, Andaluc\u00eda Tech, Campus de Teatinos, 29071 M\u00e1laga, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8503-9593","authenticated-orcid":false,"given":"Jos\u00e9 A.","family":"S\u00e1nchez-Dur\u00e1n","sequence":"additional","affiliation":[{"name":"Departamento de Electr\u00f3nica, Universidad de M\u00e1laga, Andaluc\u00eda Tech, Campus de Teatinos, 29071 M\u00e1laga, Spain"},{"name":"Instituto de Investigaci\u00f3n Biom\u00e9dica de M\u00e1laga (IBIMA), 29010 M\u00e1laga, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1185-4864","authenticated-orcid":false,"given":"\u00d3scar","family":"Oballe-Peinado","sequence":"additional","affiliation":[{"name":"Departamento de Electr\u00f3nica, Universidad de M\u00e1laga, Andaluc\u00eda Tech, Campus de Teatinos, 29071 M\u00e1laga, Spain"},{"name":"Instituto de Investigaci\u00f3n Biom\u00e9dica de M\u00e1laga (IBIMA), 29010 M\u00e1laga, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,9,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Fraden, J. (2016). Handbook of Modern Sensors Physics, Designs, and Applications, Springer.","DOI":"10.1007\/978-3-319-19303-8"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1073","DOI":"10.1109\/JSEN.2007.895965","article-title":"A new low-cost electronic system to manage resistive sensors for gas detection","volume":"7","author":"Depari","year":"2007","journal-title":"IEEE Sens. J."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"165221","DOI":"10.1088\/0953-8984\/19\/16\/165221","article-title":"Magnetoresistive sensors","volume":"19","author":"Freitas","year":"2007","journal-title":"J. Phys. Condens. Matter"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Sifuentes, E., Gonzalez-Landaeta, R., Cota-Ruiz, J., and Reverter, F. (2017). Measuring Dynamic Signals with Direct Sensor-to-Microcontroller Interfaces Applied to a Magnetoresistive Sensor. Sensors, 17.","DOI":"10.3390\/s17051150"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Arlit, M., Schleicher, E., and Hampel, U. (2017). Thermal Anemometry Grid Sensor. Sensors, 17.","DOI":"10.3390\/s17071663"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Shiiki, Y., and Ishikuro, H. (2019). Interface with Opamp Output-Impedance Calibration Technique for a Large Integrated 2-D Resistive Sensor Array. 2019 IEEE Int. Symp. Circuits Syst., 1\u20135.","DOI":"10.1109\/ISCAS.2019.8702594"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"945","DOI":"10.1007\/s00170-009-1940-z","article-title":"A 32 \u00d7 32 temperature and tactile sensing array using PI-copper films","volume":"46","author":"Yang","year":"2010","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Hidalgo-L\u00f3pez, J.A., Oballe-Peinado, \u00d3., Castellanos-Ramos, J., S\u00e1nchez-Dur\u00e1n, J.A., Fern\u00e1ndez-Ramos, R., and Vidal-Verd\u00fa, F. (2017). High-accuracy readout electronics for piezoresistive tactile sensors. Sensors, 17.","DOI":"10.3390\/s17112513"},{"key":"ref_9","unstructured":"Sherman, D. (1993). Measure Resistance and Capacitance without an A\/D, AN449, Philips Semiconductors."},{"key":"ref_10","unstructured":"Webj\u00f6rn, A. (1993). Simple A\/D for MCUs without Built-in A\/D Converters, AN477, Freescale Semiconductor, Inc."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1016\/j.measurement.2018.05.020","article-title":"Nonlinearity compensation of DIC-based multi-sensor measurement","volume":"126","author":"Dutta","year":"2018","journal-title":"Measurement"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Reverter, F. (2018). Interfacing sensors to microcontrollers: A direct approach. Smart Sens. MEMs, 23\u201355.","DOI":"10.1016\/B978-0-08-102055-5.00002-4"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"222","DOI":"10.1109\/TIM.2015.2479105","article-title":"Low-Power Direct Resistive Sensor-to-Microcontroller Interfaces","volume":"65","author":"Casas","year":"2016","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1644","DOI":"10.1109\/19.982960","article-title":"Error analysis and reduction for a simple sensor-microcontroller interface","volume":"50","author":"Custodio","year":"2001","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_15","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_16","doi-asserted-by":"crossref","unstructured":"Oballe-Peinado, \u00d3., Vidal-Verd\u00fa, F., S\u00e1nchez-Dur\u00e1n, J., Castellanos-Ramos, J., and Hidalgo-L\u00f3pez, J. (2016). Accuracy and Resolution Analysis of a Direct Resistive Sensor Array to FPGA Interface. Sensors, 16.","DOI":"10.3390\/s16020181"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Oballe-Peinado, O., Hidalgo-Lopez, J.A., Sanchez-Duran, J.A., Castellanos-Ramos, J., and Vidal-Verdu, F. (2012, January 24\u201327). Architecture of a tactile sensor suite for artificial hands based on FPGAs. Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, Rome, Italy.","DOI":"10.1109\/BioRob.2012.6290746"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Reverter, F., and Casas, \u00d2. (2008). Direct interface circuit for capacitive humidity sensors. Sens. Actuators A Phys.","DOI":"10.1109\/IMTC.2008.4547300"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Gait\u00e1n-Pitre, J.E., Gasulla, M., and Pall\u00e0s-Areny, R. (2009). Analysis of a direct interface circuit for capacitive sensors. IEEE Trans. Instrum. Meas.","DOI":"10.1109\/TIM.2009.2016782"},{"key":"ref_20","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_21","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":"Ibanez","year":"2012","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_22","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_23","first-page":"135","article-title":"Improving the resolution in direct inductive sensor-to-microcontroller interface","volume":"9","author":"Kokolanski","year":"2015","journal-title":"Annu. J. Electron."},{"key":"ref_24","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_25","first-page":"578","article-title":"Investigation of errors in microcontroller interface circuit for mutual inductance sensor","volume":"22","author":"Anarghya","year":"2019","journal-title":"Eng. Sci. Technol. Int. J."},{"key":"ref_26","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 2015 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), Pisa, Italy.","DOI":"10.1109\/I2MTC.2015.7151256"},{"key":"ref_27","unstructured":"Reverter, F. (2005). Direct Sensor To Microcontroller Interface Circuits, Marcombo."},{"key":"ref_28","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_29","doi-asserted-by":"crossref","unstructured":"Oballe-Peinado, O., Hidalgo-Lopez, J.A., Castellanos-Ramos, J., Sanchez-Duran, J.A., Navas-Gonzalez, R., Herran, J., and Vidal-Verdu, F. (2017). FPGA-Based Tactile Sensor Suite Electronics for Real-Time Embedded Processing. IEEE Trans. Ind. Electron., 64.","DOI":"10.1109\/TIE.2017.2714137"},{"key":"ref_30","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_31","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1109\/TIM.2006.887401","article-title":"Analysis of power-supply interference effects on direct sensor-to-microcontroller interfaces","volume":"56","author":"Reverter","year":"2007","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"5106","DOI":"10.1063\/1.1818531","article-title":"Optimal two-point static calibration of measurement systems with quadratic response","volume":"75","author":"Jordana","year":"2004","journal-title":"Rev. Sci. Instrum."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"536","DOI":"10.1109\/19.492782","article-title":"A novel low-cost capacitive-sensor interface","volume":"45","author":"Meijer","year":"1996","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_34","unstructured":"ISO 1993 (1995). Guide to the Expression of Uncertainty in Measurement, International Organization for Standardization."},{"key":"ref_35","unstructured":"Xilinx Inc. (2015, October 09). Spartan-3AN FPGA Family Data Sheet. Available online: http:\/\/www.xilinx.com\/support\/documentation\/data_sheets\/ds557.pdf."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Castellanos-Ramos, J., Navas-Gonz\u00e1lez, R., MacIcior, H., Sikora, T., Ochoteco, E., and Vidal-Verd\u00fa, F. (2010). Tactile sensors based on conductive polymers. Microsystem Technologies, Springer.","DOI":"10.1117\/12.821627"},{"key":"ref_37","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"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/18\/3871\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:17:38Z","timestamp":1760188658000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/18\/3871"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,9,7]]},"references-count":37,"journal-issue":{"issue":"18","published-online":{"date-parts":[[2019,9]]}},"alternative-id":["s19183871"],"URL":"https:\/\/doi.org\/10.3390\/s19183871","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2019,9,7]]}}}