Global Sources
EE Times-Asia
Stay in touch with EE Times Asia
EE Times-Asia > Controls/MCUs

Enabling utility transactions with NFC

Posted: 22 Nov 2012 ?? ?Print Version ?Bookmark and Share

Keywords:prepaid meters? smart card? Near Field Communication?

There is an upcoming trend in the area of power metering, especially in some regions. Utilities require a more sophisticated payment infrastructure to facilitate the payment process for energy. This process also reflects the recent trends in improving the security in these systems, including theft prevention. There is an appreciable trend to transition from a fixed-rate billing to a time-of-use billing. Secure prepaid meters may be used for this purpose. These types of electricity meters give the customer a greater control over their electricity bills. The target regions for using the prepaid meters are mainly the UK, Eastern Europe, Latin America, South Africa and Asia. These types of meters are suitable for installation in landlords' flats, in shops, stores and sporting facilities, etc.

The basic and common principle of prepayment in energy meters is to buy energy credit in advance and to inform the prepaid meter in some manner. This means that customers decide how much energy they need and want to consume. This solution gives the customer greater control over their energy usage. After the prepaid amount of electricity is consumed, the user is automatically disconnected from the mains unless he/she makes a further prepayment for electricity. This is the main difference in comparison to traditional power meters (based on fixed-rate billing transactions), where the customer consumes electricity continuously.

Figure: An illustration of how the secure prepaid meter works in a real application.

For the prepaid metering market, there is the need to build that payment infrastructure. Generally, a bank account, an ATM, vending stations or shops are required to reload the energy credit. The main parts of the typical prepaid meter are: the metering part that measures the accumulated energy, a contactor used for disconnecting the meter (consumer) from the mains, and a prepaid sensing element which is used for loading the energy balance onto the meter itself. According to the prepaid sensing element, we may differentiate several types of prepaid meter solutions:

???Based on an electromechanical system C prepayment is done simply by coins
???Using a meter's integrated keypad C users buy energy credit at the vendor company which generates a unique PIN which is assigned to the meter through the keypad
???Using a tokenplastic key or magnetic strip card (may be obtained from a vending machine)
???Using a memory card which is refreshed at a vending station and finally put into the prepaid meter by the user
???Using a smart card which offers the same behaviour as memory cards, but with improved security (mutual authentication, etc.)these smart cards may be contact or contactless
???Wirelessly (using a mobile phone) C mostly based on GPRS, ZigBee or NFC communicationthese technologies may be used not only for loading the energy balance, but also for wirelessly reading the smart meters' data or valuable information by authorised utilities in real-time
The following text is focused on describing in detail the prepayment solution based on the Near Field Communication technology (NFC). NFC is a special, low range (a few centimeters), wireless technology that enables devices such as smartphones to securely connect with other NFC-enabled devices, such as prepaid meters. This technology has already been proven in the banking industry, combining it with a secure microcontroller. A typical prepaid meter reference design, based on this technology, has been jointly introduced by two companies, Freescale Semiconductor (U.S.) and Inside Secure (France). This reference design, which has been developed thanks to the cooperation between both companies, provides the NFC-based prepaid meter with the ability to securely reload energy balances. This reference design uses three key parts: the Freescale MK30X microcontroller (MCU), a part of the recently introduced Kinetis series, and the secure element, the ATVaultIC460, together with the NFC (Microread 3.4) chipset, both from the Freescale partner company, Inside Secure.

The meter is driven by the Freescale MK30X256 32bit MCU, which is the heart of the metering engine. This MCU is built on the popular Cortex-M4 core. The main function of this MCU, coupled with an?ARM integrated analogue front-end (AFE), is to periodically read data from external voltage and current sensors and compute other values consecutively, mainly the powers and accumulated energies. As the main computing technique is based on the Fast Fourier Transform (FFT), the meter can measure energy precisely in all four quadrants (import/export energy, active/reactive energy). Thanks to this, the meter can perform a complete frequency analysis of the mains. The next MCU function is to communicate with on-board AMR communication interfaces, such as an optically-isolated RS232 interface, energy LEDs pulse output interface, an infrared IEC1107 interface, and an I2C/SPI interface for communication with RF/ZigBee daughter cards. The MCU also cooperates with on-board human-machine interfaces (HMI), such as an LCD, which is used for showing the demand values, and with a built-in push-button used for menu item selection.

1???2?Next Page?Last Page

Article Comments - Enabling utility transactions with N...
*? You can enter [0] more charecters.
*Verify code:


Visit Asia Webinars to learn about the latest in technology and get practical design tips.

Back to Top