Description

One of the challenges in battery operated water meters is to continuously measure the water flow information while consuming as little energy as possible. The EVM430-FR6989 used in this design features a MSP430 FRAM-based microcontroller with 100uA/MHz active-mode current: 450nA standby-mode current with the real-time clock enabled: and integrated low-power analog and digital peripherals. Additionally: the MCU offers for near infinite write endurance: quick/low-power writes: and data flexibility. This reference design demonstrates a usage example of the integrated Extended Scan Interface (ESI) on the microcontroller to achieve ultra-low power consumption compared with the same detecting methodology using an external circuit. In water meter designs: coupled to a Giant magneto-resistive (GMR) rotation detection sensor (provided): the ESI is continuously detecting the rotation of the propeller while the rest of the microcontroller is in a low-power mode. By using the ESI integrated in the MSP430 MCU: this design automates the measurement process and reduces CPU involvement: which helps to reduce overall power consumption.