Designing gas and water meters with Atmel MCUs

Gas and water meters – deployed by utility companies to measure usage stats – are typically designed to display data on a small segment LCD screen. Unlike standard electricity meters, gas and water meters are usually battery-operated, so power efficiency is clearly a key requirement.

RF communication has also become a critical feature for gas and water meters due to the advent of AMI architecture – with the Smart Electricity Meter often acting as the gateway to a utility for meter reading. In addition, an increasing number of gas and water meters are tapping into home area networks, requiring optimized security to protect data communications between devices.

The microcontrollers used in gas and water meters are generally 8- or 16-bit MCUs with ultra-low power features, often with integrated LCD segment drive capability. As such, selecting Atmel’s extensive MCU portfolio to design water and gas meters offers engineers a number of advantages.

“These include potentially best-in-class embedded 12-bit ADC and analog comparators to provide analog peripheral support, 1 µA watchdog and brown-out (monitor), picoPower to extend battery life, an event system to facilitate measurement whilst CPU is in SLEEP modes, 1.6V operation and lowest power 32 kHz crystal oscillator (650nA RTC),” an Atmel engineering rep told Bits & Pieces.

“There is also an option for embedded display controller, with high EMC performance reducing the need for external protection. Meanwhile, ±1% internal oscillators enable communications to run from internal oscillator (RC), as hardware authentication products with ultra-low standby current coupled with onboard microcontroller encryption enhances security for networked applications. In terms of transceivers, Atmel RF Transceivers offers best-in-class power consumption, while our single-chip Atmel ATmega128RFA1 combines a microcontroller and RF transceiver for efficient BOM.”

Unlike electricity measurement (voltage/current), notes the engineering rep, gas and water meters utilize a variety of parameters and techniques for flow metering. Examples include turbine and pelton wheel, optical acoustic doppler, thermal mass, vortex, magnetic, ultrasonic and coriolis flow meters (see the metrology sensor, shown in the block diagram above).

Analog-to-Digital Converters (ADC) and Digital-to-Analog (DAC) can also be useful peripherals to embed in the microcontroller, as they help facilitate flow measurement. Remember, flow meters are battery-powered, requiring power-efficient solutions capable of supporting up to 20 years of operation.

“Of course, LCD support is an important requirement. This capability can be driven serially with chip on glass, but must often be integrated into the microcontroller. Essential peripherals include serial communications and, frequently, security through encryption,” the engineering rep added.

“Dual clock input for high accuracy main clock (often used for timings in metrology) and second clock input for 32KHz for RTC. For Smart Meter and Smart Grid implementations, RF is the communication medium of choice to connect to the HAN to support AMR.”

Interested in learning more about using Atmel MCUs to design gas and water meters? Be sure to check out our extensive portfolio of MCUs that can be used to power such designs.

Putting Atmel AVR MCUs in your refrigerator

Power efficiency is an obvious, yet critical element of refrigeration design. To meet current green energy requirements, refrigerators and freezers are required to include support for global efficiency standards, as well as advanced communication capabilities for smart metering.

AVR MCUs can be used to provide flexible connectivity options and power efficient architectures that make them an excellent fit for refrigeration applications. Indeed, a variety of 8- and 32-bit Atmel microcontrollers are specifically optimized for motor control – providing full support for BLDC motors, AC motors and switched reluctance motors. As an added bonus, Atmel solutions meet energy efficiency requirements such as Energy Star and European regulations to deliver maximum efficiency.

“Atmel AVR 32-bit microcontrollers feature a multi-layer databus and DMA controller that make them a perfect fit for HMI applications where high bandwidth is required,” an engineering rep told Bits & Pieces.

“Robust touch sensor technology, featuring the Atmel QTouch library, allows designers to easily add capacitive touch buttons, wheels and sliders at no additional cost. Meanwhile, native 5 volts support is available on the Atmel megaAVR and Atmel tinyAVR microcontrollers, with node authentication capability supporting smart meter infrastructure connections. And last, but certainly not least, ZigBee Pro compatibility enables standards-compliant connectivity and smart metering.”

Refrigerators are an N1 energy consumer – understandably requiring power-efficient technology. In short, Atmel microcontrollers and wireless products are a perfect fit to help engineers design related products with granular energy control and optimized efficiency.

Interested in learning more? Additional information about the use of Atmel MCUs in refrigeration design can be found here.

The Peripheral Event System in Atmel’s SAM4L ARM Cortex-M4 based Microcontroller

Atmel’s SAM4L ARM Cortex-M4 based MCU has inherently low current consumption for such a powerful chip. But it also has a Peripheral Event System that allows you to service interrupts or external conditions without waking up the core processor.

Periphereal Event-System for Atmel’s SAM4L Cortex-M4

Keeping your microcontroller unit in sleep mode will reduce system power consumption. Increasing the throughput will reduce the time spent in active mode. Atmel’s Peripheral Event System allows peripherals to communicate directly with each other without involving the CPU (central processing unit). It is a routing network independent of traditional data paths such as system buses. Peripherals can trigger events such as data transfer to another peripheral or the copying of a message directly to the MCU internal memory. All this can happen while the processor is asleep. You spare the CPU from the time-consuming handling of interrupts since the Peripheral Event System is doing these repetitive tasks. This will free up more time for the MCU to handle other tasks in the application, or allow the MCU to remain in sleep mode for a longer time. The Peripheral Event System lowers power consumption and increases performance.

You can read more about conserving power in an Atmel white paper: Redefining the power benchmark.