Technology
globally and extensively used by Wi-Fi and Bluetooth devices. ISM |
hacking. |
spectrum is also available in sub-1-GHz bands— a common destination for IoT applications. The sub-1-GHz band is centered at 868 MHz in Europe and 915 MHz in the U. S. |
Regardless of the mechanism, it is imperative that microcontrollers are equipped with the necessary integrity features to identify when a device has been corrupted. Once |
A challenge arises when multiple devices located in close |
identified, the microcontroller can either correct the error or shut |
proximity share the same ISM band. Transmitting devices can |
the device down, ensuring that the security of the wider system is |
interfere with nearby receiving devices, such as in public hospitals |
not breached. |
that have multiple machines within the same ISM band. A radio’ s |
ability to function properly in the presence of such interferers is |
measured by the blocking specification. |
However, the challenge extends beyond devices operating within the ISM band. Without sufficient blocking capability, mobile phones or tablets operating nearby could cause a loss of communication in the system. In military and aerospace applications, very costly components are incorporated to mitigate the effect of interferers. Radios being used for mission-critical data, such as the applications mentioned, must achieve similar performance to military and aerospace without incurring the high cost of additional external components. Such radios will continue to receive messages with multiple interferers operating nearby.
Environmental Effects Degrade Performance
Radio transceivers are built on processes prone to performance variations that depend on their surrounding environment. Such variations include temperature changes, voltage-supply reductions as batteries discharge, and silicon manufacturing variations across devices. These real-life events can cause changes in the device’ s operating stability.
device. System designers must ensure that the components selected for the sensing and communication system are robust over changing environmental conditions.
Corrupted Memory Can Lead to Unexpected Outcomes
Designing for Reliability
Analog Devices’ ADF7030-1 radio transceiver and ADuCM3029 Cortex-M3 microcontroller both help overcome the aforementioned challenges. They target performance levels and functionality features that lead to more robust communication links.
Let’ s look at an event-sensing emergency-response system operating on a street light. Cold winter temperatures could cause the output power of a device to vary or the receiver sensitivity to degrade, resulting in a loss of communication. While less of a concern for a consumer device— which is rarely used in such extreme conditions— it would be unacceptable for an emergency- response system. At best, the cost is reputational damage to the end product, ending up in a service call to replace the faulty
In many cases, the ADF7030-1 will be able to receive radio signals that are 3 dB lower than other similar radios. And with blocking numbers in excess of 100 dB, the ADF7030-1 can achieve a level of interference resilience comparable to military and aerospace equipment— without the need for additional costly external components. This ultimately lowers overall cost while ensuring communication is maintained in the noisiest RF environments.
Through generations of collaboration with leading industrial manufacturers, Analog Devices has developed methods for coping with real-life environmental effects on radio transceivers. As an example, the output power transmitted by a device using the ADF7030-1 varies by less than 0.2 dB over the full operating temperature range. Competing radios, on the other hand, often vary by up to 2 dB.
The ADuCM3029 is designed with flash and error-correction-code( ECC) parity checks to ensure errors caused by memory corruption are identified and corrected where possible. The microcontroller also comes with battery-monitoring capability in sleep mode. This ensures that unexpected drops in voltage are detected, and that the processor is in turn alerted to a possible malicious threat or power-supply malfunction. The end device can then take appropriate action, either by alerting an administrator or entering a safe mode to ensure the wider system is not compromised.
Reliability is also a concern for the communications microcontroller. Although extremely reliable, both flash and non- volatile memory can occasionally become corrupted. This may occur as a result of unintended effects caused by the operating environment, or intentionally through malicious hardware
Technologies developed by Analog Devices inhabit every stage of the IoT signal chain, from sensing and measuring to interpreting and connecting the data. Ensuring the quality and integrity of the information created through this chain is a core design principle, and a fundamental requirement to fulfill the true potential of the IoT.
ELE Times | 26 | March, 2017