BioHarness Bluetooth Developer Kit User Manual
Page 30
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This document has been prepared by Zephyr Technology Ltd and is not to be distributed, copied or reproduced without permission.
9700.0026 © Zephyr Technology 2010 2010-06-02
6. Device Worn detection
The BioHarness BT has worn detection circuitry. If the device detects insufficient resistance
across the uppermost pair of snaps, then it can respond to a request and send a ‘Not Worn’
indication. See the BioHarness Bluetooth Comms Link Specification document for details on the
message and response to determine this.
Using this information, it is possible to configure the device to NOT respond to a button press on
the front of the device if it detects it is being worn. This is to prevent accidental powering off of the
device in the field.
If this setting is enabled, then the device must be removed from its strap before being powered
off. Care must be taken to avoid contacting both upper snaps simultaneously with fingers as you
grasp the device to power off, as the resistance detected may prevent device power-off.
The device may not detect it is being worn if there is a poor conductive path while it is actually
being worn. This is typically caused by insufficient moisture, either in the sensor pads, or on the
subject’s skin. Moisten the sensor pads with water if this is observed.
The device may also detect it is worn when the strap is not on a subject, if there is sufficient
moisture within the strap itself to create a conductive path – i.e. if the strap itself is saturated.
Users should be aware of this possibility.
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