Table of contents
- Table of contents
- Device Description
- Operational Modes
|Rev# 1.0: 12.09.18||as||ml|
- Node - A wireless Vicotee sensor node.
- End Point - Gateway/Server where sensor data is aggregated.
- LED - Light Emitting Diode
- Driver - A specific set of instructions used to access and read measurement data from a sensor.
- Vicotee Configuration Gateway - A Vicotee device used for post-configuration of the nodes.
- OTAA - Over The Air Activation, a method of connecting a node to a LoRaWan network.
Vicotee nodes contain a single bi-colored LED which is used to indicate various states and to provide user feedback. Green light is used to indicate states and/or state transitions which do not require user intervention, while Red light is used to indicate errors and/or states which may require user intervention.
Please refer to Operational Modes for more information.
Vicotee nodes are equipped with a single push-button which is used to turn a node on/off and for
entering configuration mode. Additionally the button can be used to trigger a message to be transmitted to the end-point when a device is in Active mode. Please note, that the functionality of the button may be overridden by application-specific driver configuration which can be uploaded to a device after production. Internally the button is designed to trigger bi-directionally (i.e. capable of detecting both activation and release) with a constant timeout value of 10 seconds.
Vicotee nodes are equipped with a magnetic reed switch which is connected in parallel with the button and thus provides exactly the same functionality as the push-button described above. The reed switch pull-in range is specified to 20..25 AT (Ampere-Turns). Please refer to Application Note for more details regarding selection of a proper magnet.
Vicotee nodes can be equipped with up to two CR123A batteries with a total capacity of 3.1Ah. Typical quiescent voltage values for lithium batteries after initial run-in is about 2.7V at 20°C and 2.4V at -30°C. Values given here assume a sample rate of 3 minutes with default sensors activated. Default sensors consist of Temperature and Humidity driver and an internal battery status driver.
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Vicotee nodes have four states, referred to as operational modes. Boot-up, configuration, active, and shutdown. Devices spend the majority of their life time in active state where they sample and transmit sensor data to a specified end-point maintaining extremely low quiescent current in-between measurements allowing the device to operate for years without the need to change batteries.
Vicotee nodes enter boot-up mode once batteries are inserted and the button is pushed and held for at least a second. The device will signal that it has booted up by turning on the green LED for one second. Following this the LED will switch from the green to red light for four seconds during which it is possible to manually enter configuration mode. If configuration mode is not entered the device will automatically transition to active mode. Note that the device will also enter configuration mode if no valid settings are found on the device or if the device receives a command to enter configuration mode from the end-point while being in active mode.
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As mentioned in the previous section, the node can, manually, be sent into configuration mode, this is achieved by pressing, the push-button immediately after the LED changes from green to red and holding it until the red LED switches from being constantly lit to blinking 3 times with 0.25 seconds interval. Unless proper configuration is transferred to the device via Vicotee Configuration Gateway the device will remain in configuration mode for 10 minutes after which it will shutdown. The device will notify that it is in Configuration mode every 5 seconds by blinking the red LED once. If proper configuration is received by the node, it will transition to active state. The node can also be forced into configuration mode remotely by issuing a specific command from the end-point while being in Active state.
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Upon entry into Active mode, the device will attempt to join a network using OTAA mode using the keys uploaded to the device either during configuration mode or during pre-configuration at an earlier stage. Upon successful join procedure the node will indicate this by blinking the green LED 3 times (1 second on, 0.5 seconds off). After join procedure is completed, the node will identify itself by transmitting configuration specific information (driver(s) loaded, firmware version, etc.), further the node will initiate all the configured drivers to the specified sample rate(s) and maintain that mode for the rest of the lifetime unless external user stimuli forces it into another operational mode.
When in active mode a node can be forced to transmit a message to the end-point by briefly pushing the push-button. This can be used for testing/debugging during deployment phase. Please note that the push-button functionality may be overridden by user-specific drivers and thus the intended response from the device may differ from the default one described here.
If the node is unable to join the specified network (could happen due to reasons like invalid keys, inability to reach network due to distance or interference) within 60 seconds of entering active mode, it will reboot into a low power mode for the next 10 minutes conserving the battery. Once the sleep period elapses, the device will reboot in order to re-attempt the join procedure.
While in Active mode, the device may be forced into shut-down mode if the push-button is pressed, and held, for at least 30 seconds (given that the push-button functionality is not overridden). Upon release of the push-button, after the 30 seconds have elapsed, the node will turn the green LED on for 5 seconds before fading. The device is now turned off and may be re-started as described in the Boot-up section above. Device shutdown can also be performed remotely by issuing a specific command from the end-point.
Please note that once the device has been turned off via the push-button, external command, or by, simply, removing the batteries, internally, the device still has some charge accumulated and thus, to avoid turning the device back on accidentally let the device rest for a minimum of two minutes before re-starting or re-inserting batteries.