Saboten means “cactus” in Japanese and was designed from the ground up as a ruggedized wireless sensor device for environmental monitoring. It comes with an IP65 waterproof, weatherproof enclosure to protect the circuitry and internals from exposure to harsh outdoor conditions as well as water, insects, and dust. Saboten is the culmination of many outdoor environmental monitoring projects performed by members of FreakLabs. These projects have taken us from measureing water levels in the mountains of the Himalayas to radiation monitoring in the deserts of Egypt with many places in between. From the experiences from these projects, we’ve built up an expertise in outdoor environmental monitoring and what constitutes a good, ruggedized, outdoor wireless sensor device. The Saboten has been used by organizations such as the World Bank, UNESCO, Qatar Foundation, International Atomic Energy Agency, and many more.
- Long range 900 MHz radio with up to 500 mW output power
- ATMega1284P Arduino compatible microcontroller with 16 kB RAM and 128 kB flash (8x RAM and 4x flash of standard Arduino)
- Solar powered Lithium-ion charging circuit
- Power optimized system under 0.2 mA of current in deep sleep mode (>1 year on single battery charge)
- Battery backed, temperature compensated real time clock and calendar with two alarm outputs
- Ruggedized IP65 waterproof, weatherproof enclosure
- External standard antenna connector with wide choice of antennas
- On board temperature sensor to monitor internal enclosure temperature
- Circuitry to monitor battery voltage
- Circuitry to monitor solar panel voltage
In wireless sensor networks, the number one feature is power consumption. Saboten was designed and optimized to be an extremely power efficient device to survive as long as possible in whatever environment it’s put into. The circuitry has been painstakingly optimized to minimize stray currents and in deep sleep mode consumes only 0.2 mA of current. This equates to over one year of life on a single battery charge using a typical 2000 mA-Hr battery. But we didn’t stop there. We also added a solar powered charging circuit that can power the system and the battery. With this setup along with the low power properties of the system, the device can run indefinitely.
The wireless radio that comes with Saboten uses the IEEE 802.15.4 wireless sensor data protocol, an open standard, and comes in either 2.4 GHz or 900 MHz versions. On the Saboten 900, the radio has been optimized and tuned for long range and consists of the base 900 MHz wireless circuit and amplifiers on both the transmitter and receiver. The transmitter is powered by a 500 mW amplifier, a 50x boost compared to the stock radio. On the receiver, the received signal is boosted by up to 10x to improve receiver sensitivity. The modulation can also be switched for further improvements in sensitivity, often providing an additional 10x improvement or more in performance at the cost of a slower bitrate. On top of that, the system has an external antenna connector that can be connected to standard antennas or high gain antennas. With a properly optimized system, its possible to transmit data over long distances measured in kilometers rather than meters.
The Saboten was designed for rapid prototyping and to be accessible to a large audience that might not be specialists in programming microcontroller based embedded systems. Because of that, we chose to maintain as much compatibility with the Arduino environment as possible and its multitudes of libraries and drivers. The microcontroller used on the Saboten is completely compatible with the Arduino environment and can use the standard Arduino IDE and libraries. However Saboten uses an ATMega1284P, an upgraded version of the standard Arduino microcontroller, with 16 kB of RAM and 128 kB of flash. This is 8x the RAM and 16x the flash of the standard Arduino Uno and allows you to implement much more fully featured applications without worrying about running out of RAM or flash storage.
Real Time Clock
Saboten also comes with a temperature compensated real time clock. One of the most important features of a real time clock is having an external battery backup. If the device ever fully loses power, the clock will lose time and calendar data which is considered a catastrophic failure in many instances of data collection due to timestamping. Having an external backup battery allows the device to run all the way down to zero battery and still maintain knowledge of the current time and date. That way, once power is restored, via solar panel or other means, it can start performing as if nothing happened. Also, the real time clock has an internal temperature sensor which allows it to compensate for temperature. Temperature variation has a drastic affect on timing accuracy which is why many outdoor clocks quickly fall out of sync quickly. With temperature compensation, this effect can be minimized and the clock can maintain accurate timing when located outdoors, even under varying temperature conditions.
Finally, the real time clock can be programmed with two alarm outputs which can issue an interrupt to the processor. These interrupts can be used to wake the processor up and specific times every minute, hour, day, or even day of the month. This is extremely useful when you need to run with very little power and are just monitoring something that changes slowly, such as temperature. In this case, you can use the real time clock to wake up the controller and sample, log, and transmit the temperature data once every hour, then immediately go back to sleep again. Using a method like this, the Saboten can survive over six months on a single charge with proper power management and optimization.
The Saboten 900 also comes with a micro SD card slot for storing large amounts of data. Using the micro SD card slot, you can turn the Saboten into an offline data logger as well as a wireless sensor device. You can store offline backups of the data you transmit as well as diagnostic data that can later be used to diagnose any problems that may be experienced in the field.
There is also circuitry on the Saboten board to monitor and transmit system parameters. At FreakLabs, we know what it’s like to set up wireless sensor networks and the kinds of information you need to know to be able to monitor and maintain them. We’ve added circuitry to monitor the battery voltage and solar panel voltage which allows you to see if the charging system is functioning correctly and also when the system is about to run out of power. There is also an on-board temperature sensor which allows you to monitor the internal enclosure temperature to make sure its within the operating parameters of the system.
One of the most useful features of the Saboten is the IP65 waterproof, weatherproof enclosure. This allows it to be used outdoors with no worries of insects or water getting in, typical failure modes for many outdoor environmental monitoring devices. The enclosure maintains a gasket seal around the main cover and any cables that enter or leave can do so using optional gasketed cable glands. The enclosure also has mounting ears to make it easy to mount to flat surfaces with no additional mounting hardware. Mounting the monitoring devices is often a big headache that people forget about when designing outdoor environmental monitoring systems.
Saboten is the distillation of all the experience we’ve had working on outdoor environmental monitoring projects in harsh environments. It contains our wishlist of product features that we wanted when working on remote environmental monitoring projects. It’s the most affordable product on the market targeted specifically at outdoor environmental monitoring for research scientists, citizen scientists, and people that just want to monitor their outdoor sensors. We hope you give it a try and find it useful. We’d also love to hear what kind of project you’re working on.