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DC2126A - High-Accuracy Wireless Temperature Sensor with Solar Battery Life Extender

DC2126A Exploded View

The DC2126A is a high-accuracy wireless temperature sensor, powered from ambient light, built using Linear Technology integrated circuits. A 24-bit delta-sigma ADC reads a thermistor biased from a precision voltage reference. A switching power supply harvests energy from the built-in solar panel, and automatically switches over to the internal battery when no ambient light is available.

At the core of the DC2126A is the LTP5901-IPM, SmartMesh IP wireless mote (node), which provides the ultra-low power wireless mesh connectivity with >99.999% data reliability and communicates the temperature to a central access point (manager). The LTP5901-IPM has on board an ARM Cortex-M3 processor, which can be loaded with user-developed application code using the SmartMesh IP On-Chip Software Development Kit (On-Chip SDK). In the DC2126A, custom application code controls the duty cycling of the voltage reference, samples readings from the ADC and sends the data packet through the SmartMesh IP network, as detailed in this LT Journal article.

DC2126A Block Diagram 2A wireless temperature sensor is formed by conecting a wireless radio module to an ADC, reference and thermistor. The circuit is powered by an energy harvester that can take power from a battery or solar panel.

LTC Part Number Function Benefits
LTC2484 24-bit delta-sigma ADC, reads thermistor Easy-Drive inputs allow direct hook-up of thermistor
LT6654 Low Noise Voltage Reference Bias thermistor for low noise reading of temperature
LTP5901-IPM SmartMesh IP Mote PCB Module

Automatically forms low power, reliable wireless mesh network.Built-in microprocessor manages ADC and power supplies

LTC3330 Energy Harvesting DC/DC Converter Prioritizes between solar power and battery power

 The DC2126A  can be easily added to the DC9000B SmartMesh IP Starter Kit, or any SmartMesh IP network. Temperature readings are sent through the mesh network to a demonstration PC software GUI that displays temperature, and whether the DC2126A is running on solar power or on battery.

DC2126A Software UtilitiesDC2126A Software Utilities

Additional References

DC2126A Demo Manual - step by step instructions to operate the DC2126A

DC2126A Circuit Description (from LT Journal, July 2014) - describes theory of operation of the DC2126A circuit

SmartMesh IP Starter Kits - other SmartMesh IP demo boards

SmartMesh IP On-Chip Software Development Kit - Enables users to develop application code to run on a SmartMesh IP Mote

 software utilities

Software Name Software Description Weblink
"DC2126A.exe" Demonstration GUI software that displays temperature and power source data sent wirelessly through the mesh. Runs on the user's Windows PC connected to a SmartMesh IP network manager. Part of the SmartMesh IP SDK
FTDI Driver USB-to-Serial drivers for communication with a SmartMesh IP manager (e.g. DC9001B SmartMesh IP Evaluation manager) Download VCP from ftdichip.com

 

Companion Demo Boards

DC9006A - Eterna Interface Card
DC9010B - Eterna Serial Programmer
DC9021B - SmartMesh IP Starter Kit