The next generation of solar-powered sensor modules

With the STM 110 EnOcean is launching the next generation of its solar-powered sensor module for batteryless and wireless transmission of a variety of data. Now the STM 110 manages with even less light. Plus there is a 315 MHz variant STM 110C immediately obtainable for the North American market. The STM 110 is the perfect answer to needs for efficient wireless sensors, doing away with the high power requirement of a conventional radio solution and the inadequacies of a battery, such as short service life, maintenance and disposal.

The STM 110 sensor module, like its predecessor STM 100, was developed with the aim of creating a maintenance-free wireless device to transmit various kinds of sensor input. Its power comes from the accompanying solar cell, just 13 mm x 35 mm in size. An integrated energy accumulator ensures full functionality even after a number of days of complete darkness.

In addition to being battery-less, the STM 110 wireless sensor module emphasizes application flexibility. All major functions (A/D converter, microcontroller, wireless transmitter, antenna, energy management) are ready incorporated in the module. For the user that means very simple implementation of maintenance-free wireless sensors for temperature, brightness, humidity, vapor, gas, current, water and pressure, for example:

• Temperature and humidity sensors for HVAC
• Brightness sensors for illumination control
• Window and door contacts to supervise status and locking
• Industrial sensors for temperature and position

As Armin Anders, EnOcean product manager, explains: "Compared to the forerunner STM 100, the new STM 110 wireless sensor module manages with even less light. Previously the lowest operating limit was luminance of about 100 lx, but the new module works upwards of just 50 lx. This performance enhancement is the result of an improved solar cell, plus the operating range of the module, and thus the solar cell voltage was expanded to 2.2 through 5 volts." The essential differences between the STM 110 and the predecessor model are as follows:

• Improved solar cell performance (operates upwards of 50 lx)
• Expanded operating voltage range (2.2 to 5 V)
• Faster wake-up timing (from 7 ms switchover time)
• ADC inputs with configurable signal trigger thresholds
• Possibility of configurable device coding: telegram transmission of device profile and producer information
• 868 MHz (Europe) and 315 MHz (North America) frequency variants