The wireless transformation of water meter faces three constraints:the battery can not be replaced,the signal coverage is unstable and the circuit board space is tight.In this scenario,the low-power Bluetooth(BLE)MCU needs to solve the problems of measurement and sampling,low-power operation,local copy and display drive at the same time,which is the core of the whole scheme.
1.Overview of the MCU scheme of BLE domestic Bluetooth single chip microcomputer
The main control is selected according to the project requirements:CH582M provides 4 UART and 40 GPIO,and the sleep current is about 3μA,which is suitable for the whole machine with rich IO resources and more peripherals;CH592X provides 4 UART's and 24 GPIO's,the sleep current is about 2.6μA,and the average power consumption is lower,which is more suitable for the model with long battery life as the primary goal.However,the LCD of CH579M consumes a lot of power,so it is not suitable for the constant display water meter,and there will be a pin to pin model to replace it in the future.
On the software level,the main control of domestic Bluetooth single chip microcomputer takes RTC timing wake-up and long sleep as the main beat,and RF and metering sampling are processed in a centralized way according to the window to compress the RF start-up time;The water quantity data is accumulated and stored locally,reported in batches by BLE during meter reading,and uploaded by concentrator via NB-IoT or LoRa.
2.The advantages of domestic Bluetooth microcontroller Bluetooth water meter scheme
The volume of water meter body is limited,and the integration directly determines the feasibility of the scheme.After BLE,LCD driver and metering interface are integrated into a single chip,the external display driver and coprocessor can be omitted,the pressure of board layout can be relieved,and the static power consumption of the whole machine can be reduced.
The compatibility of measurement interface is also the key:the peripheral devices such as Hall sampling,ultrasonic serial port,infrared and 125 kHz smart card have different shapes,and the master controller of domestic Bluetooth single chip microcomputer needs to cover different types with enough GPIO and UART resources,so that the same platform can be reused for mechanical watches and ultrasonic meters to reduce repeated development.
3.The scheme selection of domestic Bluetooth microcontroller Bluetooth water meter
The scheme of battery-powered water meter should take the dormant current,average power consumption and starting voltage as the primary indicators,and then check whether the power consumption of LCD display,the number of UART and the size of GPIO cover Hall or ultrasonic interface and select communication peripherals;If the normal display scheme is adopted,it is necessary to evaluate the occupation of LCD driving current on the six-year life budget.If you need to know more about water meter scheme details and product selection information,please call us.
Keywords:Bluetooth single chip microcomputer
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