NEC Yamanashi MR and Renesas MCU Smart Water Meter Solution

The development of water meters has a history of nearly 200 years. In the early stage, water meters from countries such as Britain, France, Japan and Germany have always occupied the Chinese water meter industry for a long time. With the development of urban water supply, China's water meter industry has also developed accordingly. Since the 1990s, various intelligent water meters, water meter reading systems and other products have also begun to emerge.

Although the domestic water meter market is still dominated by mechanical meters, from a development perspective, intelligence is an inevitable trend, which can save labor, improve the accuracy of meter reading, and realize tiered charging, and effectively utilize limited water resources.

The power supply of the water meter is generally supplied by the water meter itself, which puts forward stringent requirements on the power consumption of the water meter. According to international regulations, the static current of the intelligent water meter should be less than 30μA. In practice, water meter manufacturers control this indicator within 10μA (when using a reed switch sensor) and ensure that the working time is more than 6 years to be qualified. NEC's 8-bit microcontroller with LCD control function has become a high-quality choice for water meter microcontrollers due to its advantages such as low power consumption and high performance.

NEC Yamanashi MR and Renesas MCU water meter solution:

The working principle of this solution is: a magnet is installed on the impeller, and the magnetic field sensor (MR Sensor) senses the rotation of the impeller. The magnetic field sensor (MR Sensor) converts the magnetic field signal into an electrical signal, and then the microcontroller performs the addition or subtraction operation of the measurement, and the operation value is displayed on the LCD or output to the outside.


The scheme structure diagram is as follows:

Renesas MCU——78K0/Lx3 microcontroller introduction

Renesas Electronics 78K0/Lx3 microcontroller is a high-performance 8-bit general-purpose microcontroller, using the original NEC Electronics 78K0 core, with 48Pin~80Pin multiple packages, built-in 4Com/8Com mode LCD driver, can drive up to 288 LCD segments.

LCD driver

Maximum 36*8 segment control can be achieved, a total of 6 display modes to choose from, internal/external group voltage.

CSI communication module 1~2

can communicate with IC card receiver, short-range wireless transceiver, ultrasonic flow sensor

Rich comparison/trigger timer

Collect flow sensor signals and accurately calculate the flow

EEPROM simulation function

Store important data through flash data burning and special management methods instead of EEPROM Oscillator

circuit

78K0/Lx3 microcontroller has a built-in high-precision 8MHz oscillation circuit, and the speed of the internal oscillation circuit can be controlled through registers. For water meters that do not require a real-time clock, it can save costs and speed up software development. If you need to use RTC, you need to connect an external 32.768kHz oscillator, which can easily realize the stepped multi-rate water fee. The static power

consumption

of 78K0/Lx3 is less than 1μA, which can effectively extend the battery life and help improve the stability and anti-interference of the system. The operating voltage of 1.8V~5.5V can maximize the use of battery energy. The built-in 16-level LVI module eliminates the worries of customers and monitors the battery voltage at any time. Once the battery voltage drops beyond the limit, it will immediately notify the user and store key data. The NEC electronic water meter solution is a card meter solution that supports a variety of reader-writer cards and communicates with the microcontroller through the card holder using the IIC protocol. The microcontroller uses 78K0/Lx3 with LCD display control function. In terms of power consumption, through various power-saving measures, the whole machine achieves an ultra-low power consumption of 3.8μA.

[page]

NEC Yamanashi MR sensor

NEC Yamanashi's MR magnetic sensor is a magnetic switch device that uses the principle of magnetoresistance reaction to evaporate a strong magnetic metal alloy film on the IC circuit. Its characteristics are:

high sensitivity, high precision - the consistency of sensitivity can reach up to 6 gauss.

High reliability - built-in temperature protection circuit, greatly improving the stability of temperature characteristics.

Low power consumption - working current 1.5mA, working in pulse mode, the average power consumption can be reduced to 0.45uA.

Low cost.

Small package.

Compared with various different sensing devices:

NEC Yamanashi MR sensor application in water meter

Magnetic sensors are suitable for speed-type water meters, which can be divided into rotor type and propeller type. Different magnetic field distributions have corresponding magnetic sensors.

Case 1: Horizontal direction detection

Case 2: Vertical direction detection

Functions and features of NEC Yamanashi MR and Renesas MCU water meter solution:

Instantaneous flow indication

Water leakage detection alarm function

Excessive flow detection alarm function

Backflow detection

Zero flow detection

NEC Yamanashi authorized agent Shiqiang Telecom will provide high-performance products and technical support for this solution. Please call Shiqiang Telecom directly.