1 Introduction

Applications for weight, force, torque, and pressure measurement frequently use resistive full-bridge sensors. Most of the bridge sensors require a high excitation voltage (typically in the 10-V range) and output a low full-scale differential voltage in the range of 2-mV/V excitation voltage. The output from the sensor is typically amplified by an instrumentation amplifier. After signal conditioning, the signal is digitized by a high-resolution ADC. Typically, such high-resolution ADCs are not integrated in conventional microcontrollers (MCUs). A general-purpose MCU is then used for further processing and display.

The conventional approach of using a bridge sensor excitation voltage of 10 V and an Instrumentation amplifier to achieve a full-scale ADC input voltage increases chip count and complexity of power management with high power consumption. An energy-efficient and cost-effective solution is to use a microcontroller with an integrated high-resolution ADC and an integrated programmable gain amplifier (PGA). The entire application can then be powered from a 3-V battery. The MSP430F427A microcontroller (MCU) has integrated 16-bit sigma delta ADCs with differential inputs and PGA with gain up to 32. This device offers a single-chip solution for this application that includes not only high-resolution ADCs with PGA but also an LCD driver and brownout protection.