Direct sensor-to-microcontroller is a simple approach for direct interface of passive modulating sensors to a microcontroller without any active components in between the sensor and the microcontroller and without an analog to digital converter. The metrological performances of such interface circuits are limited by certain microcontroller parameters which are predetermined by the manufacturing technology. These limitations can be improved by specific hardware-related techniques and can improve the accuracy, speed and resolution of the measurements. Such hardware solutions as well as proper selection of the electrical components are addressed in this paper. It has been shown that employment of only a few MOSFET transistors can reduce the maximal relative error of single point calibration more than fifteen times and can increase the measuring speed around 30 % in all calibration techniques in the measurement range of PT1000 resistive temperature sensors. Moreover, the effective number of resolution bits increases by more than 1.3 bits when using an external comparator.
 Reverter, F., Areny, R. P. (2005), Direct sensor to microcontroller interface circuits, Barcelona: Marcombo S.A.
 Bengtsson, L. E. (2012), Analysis of direct sensor-to-embedded systems interfacing, International Journal of Intelligent Mechatronics and Robotics, (2), 41−56.
 Pelegri-Sebastia, J., Garcia-Breijo, E., Ibanez, J., Sogorb, T., Laguarda-Miro, N., Garrigues, J. (2012), Lowcost capacitive humidity sensor for application within flexible RFID labels based on microcontroller systems, IEEE Trans. Instrum. Meas., (61), 545-553.
 Sifuentes, E., Casas, O., Pallàs-Areny, R. (2011), Wireless magnetic sensor node for vehicle detection with optical wake-up”, IEEE Sens. J., (11), 1669−1676.
 Costodio, A., Areny, R. P., Bragos, R. (2001) Error analysis and reduction for a simple sensormicrocontroller interface”, IEEE Trans. Instrum. Meas., (50), 1644−1647.
 Van der Goes, F. M. L. (1996), Low-Cost Smart Sensor Interfacing”, Delft Univ. of Technol., Ph. D dissertation.
 Lira, H., Wogel, W. (1997), The evaluation of standard uncertainty in presence of limited resolution of indicating devices, Meas. Sci. Technol., (8), 441−443.
 Reverter, F., Areny, R. P. (2004), Effective number of resolution bits in direct sensor-to-microcontroller interfaces”, Meas. Sci. Technol., (15), 2157−2162.
 Areny, R. P., Jordana, J., Casas, O. (2004), Optimal two-point static calibration of measurement systems with quadratic response”, Rev. Sci. Instrum., 75(12), 5016−5111.
 Reverter, F., Gasulla, M., Pallas-Areny, R. (2007), Analysis of power supply interference effects on direct sensor-to-microcontroller interfaces”, IEEE Trans. Instrum. Meas., (56), 171−177.
 Zaworski, L., Chaberski, D., Kowalski, M., Zielinski, M. (2012), Quantization Error in Time-to-Digital Converters”, Metrol. Meas. Syst., 12(1), 115−122.
 PIC16F87X CMOS Flash Microcontroller, Datasheet for Microchip. ww1.microchip.com/downloads/en/devicedoc/30292c.pdf. (2001)
 IRF7311 Power MOSFET, Datasheet for International Rectifier, www.irf.com/productinfo/datasheets/data/irf7311.pdf. (2001 November).