Reference Designs

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 LC 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.