Nordic Semiconductor Bluetooth low energy solution reduces installation time of switches in building automation applications

Grässlin talento smart employs nRF51822 SoC for wireless programming and commissioning of digital time switches

Nordic Semiconductor today announces that Grässlin, a St Georgen, Germany-based company specializing in time-switch technology has selected Nordic’s multiple award-winning Bluetooth®low energy (previously known as Bluetooth Smart) nRF51822 System-on-Chip (SoC) for its “talento” smart digital DIN-rail time switches.

The talento smart digital time switches allow electricians to quickly and efficiently install, program, and commission electrical time switches in a range of applications such as street or window lighting, temperature and ventilation control, machinery control, as well as home and building automation. A time switch can switch equipment on and off, at a preset time or times, after a preset interval, cyclically, or even based on astronomic sunset or sunrise.

Powered by the Nordic nRF51822 SoC, talento smart provides Grässlin smartlink Bluetooth low energy wireless data transmission between the time switches and the user’s Bluetooth 4.0 (or later)-enabled device. This allows electricians to transfer and copy programs and data between their device and the time switch, even when the cabinet door is closed.

The talento smart switches are equipped with up to 800 memory spaces and can be preprogrammed, adjusted, and managed easily from a PC, tablet, or smartphone, using the Grässlin iOS or Android app or PC software. The time switches can be programmed even before arrival on site, saving time prior to the physical installation. Two modes provide fast access to the most common as well as complex time switch functions. For example, the ‘wildcard’ function allows for the easy programming of recurring events, while the ‘quick copy’ function permits electricians to rapidly transfer existing programs between their device and the time switch.

“With the [Bluetooth low energy] wireless technology, the user can program the device much easier and faster than with the existing four button keypad on the device. The programming can now be done on an external smartphone,” says Dominik Schröder, Technology at Grässlin.

The core feature of the application firmware is to calculate valid switching events for the actual day. These switching events must be calculated out of up to 80 different programs with up to 800 commands, while each program can have a date dependence and a different priority. If a timer receives a program via Bluetooth low energy, the application firmware directly starts to calculate if there are any valid switching events for that day. Meanwhile a multilanguage menu gives the user the ability to program the time switch directly from the four-button keypad.

Nordic’s nRF51822 is a powerful and flexible multiprotocol SoC ideally suited for Bluetooth low energy and 2.4GHz ultra low-power wireless applications. The nRF51822 is built around a 32-bit ARM® Cortex™ M0 CPU with 256kB/128kB flash and 32kB/16kB RAM. The embedded 2.4GHz transceiver is fully compliant with Bluetooth 4.2, the latest Bluetooth low energy specification.

“We considered NFC technology, but with NFC the user would have to cover the device with the mobile during data transmission,” says Schröder. “With Bluetooth low energy’s greater range the user can stand relaxed in front of the control cabinet and still program the time switch.

“We chose the nRF51822 chip because of the good price/performance ratio. It is our first product with a Nordic chip integrated and the support during development has been great.”

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