Understanding Smart Sensors - Nomads.usp

Using MCUs/DSPs to Increase Sensor IQ 111MPX2100AP3 24 1MC7HC4053MC3076−++−V1V2R fR gR fV DD+5 VVRHCH1VMC68HC05B6PCH2VR V SS0VFigure 5.9 Calibration-free pressure sensor system.not require any calibration procedure. For a ±1% measurement, the full-scaleoutput is set at 25°C.5.5.4 DiagnosticsOne of the more valuable contributions that the MCU can make to the sensor’sfunctionality is the ability to self-test, analyze status, diagnose, and report problemsto an operator or other systems that use the sensor’s output. The problemcould be as simple as a warning for maintenance or calibration or an indicationof catastrophic failure that would not allow the system to function whenrequired. For example, an automotive air bag system may operate for yearswithout requiring deployment. However, knowing that the sensor is capable ofproviding the signal to indicate a crash event is part of the safety the systemroutinely provides the driver and passengers. In the air bag system, a dash indicatorlamp is activated by the MCU to indicate that it has performed a systemreadyanalysis.5.5.5 Reducing Electromagnetic Compatibility and Radio FrequencyInterferenceRadiated RFI and electromagnetic interference (EMI), both the transmittingand receiving of unwanted signals or EMC, of a device are becoming an importantdesign consideration with increasingly higher levels of system integrationand higher processing bandwidths. These problems can be reduced at the componentlevel with smaller radiation loops and a smaller number of signal lines.Power management in the MCU can also eliminate some self-induced effects