Ultrasonic Water Meter Solution

The E703.15 launched by ELMOS for ultrasonic flow meter applications offers high integration, high accuracy and low power consumption, making it suitable for ultrasonic water meters, ultrasonic heat meters, ultrasonic gas meters and similar applications. Built around the E703.15, we have developed a complete ultrasonic water meter solution featuring flow measurement, flow data storage, LCD display, M-BUS wired meter reading and LoRa wireless meter reading. It helps customers evaluate quickly and accelerates the path from development to mass production.

Solution Overview

Built around the E703.15, we have developed a complete ultrasonic water meter solution featuring flow measurement, data storage, LCD display and M-BUS meter reading.

Recommended MCU

• ELMOS: E703.15: 16-bit 430 core; 5kB RAM / 32kB Flash; low power consumption; integrated hardware floating-point unit; built-in two-stage amplifier; supports common basic peripherals

Core Components

• Main chip: E703.15 (ELMOS)
• LCD driver: PCF8551 (NXP)
• Card reader IC: FM17520 (Fudan Micro)
• EEPROM: FM24C02 (Fudan Micro)
• M-BUS transceiver: NCN5150 (onsemi)

Key Advantages

• Highly integrated: the E703.15 embeds a 16-bit MCU together with ultrasonic measurement peripherals, a high-precision floating-point unit and the common basic peripherals.
• Accurate first-wave detection: the E703.15 includes an internal voltage comparator that can detect three voltage levels — High Level, Low Level and Trigger Level — each independently configurable. Detecting across these three levels allows the position of the first wave to be captured precisely.
• Automatic gain control: the E703.15 contains a two-stage amplifier. The first stage has a minimum gain of 1.76 and a maximum gain of 104.5, the second stage a minimum gain of 0.64 and a maximum gain of 65.3, giving a combined gain range of 1.13 to 6824. Hardware high-pass and low-pass filters are also included. The internal gain can be adjusted automatically in software based on the first-wave detection voltage.

Reference Design Flow Meter

• Wide turndown ratio (400:1)
• Low start-up flow rate
• High accuracy at low cost
• Flow sensor under-voltage alarm, empty-pipe indication and drip/leak warning
• Built-in lithium battery supply ensures a service life of more than (6+1) years
• Choice of M-BUS or wireless communication interface