7 Unihedron Device Manager
7.11 Accessory options
Some meters can be equipped/retro-fitted with optional accessories if they include firmware feature version
≥
40.
See section 8.4 for details on the accessory commands.
The accessories tab (shown in 7.35) is available when selecting a device that has the appropriate firmware:
Figure 7.35: Accessories tab
7.11.1 Humidity accessory
There are currently two types of I
2
C humidity sensors that have been tested; HIH8120, and HYT939. The selection can
be made with the drop down combo-box on this tab.
Enabling this sensor allows the SQM-LU to poll the sensor once per second to gather a reading which can be requested
later with the A1x command.
The refresh button requests the most recent value that the SQM-LU has collected.
The Status field shows the status of the humidity sensor which is updated after the refresh button is pressed. The
status is ‘N/C’ when the sensor is not connected.
7.11.2 Display accessory
A 4-digit 7-segment I
2
C display can be attached to the SQM-LU. Currently only the Sparkfun COM-11441 has ben tested.
This display shows the brightness reading in mpsas.
The brightness of the display can be fixed at a level between 0-7 (dimmest to brightest), or can be automatically dimmed
in bright conditions (depending on the mpsas reading).
The display can be either updated periodically (1Hz) or whenever a reading request is made.
7.11.3 LED accessory
The LED indicator accessory is mainly used for troubleshooting to identify either when readings are created or requested.
The The LED blinks for 1/60th of a second.
The LED can blink either when the SQM-LU creates a reading, of when a reading is requested (using the rx command).
7.11.4 Relay accessory
The Relay accessory is mainly used for dew heater control. A 3.3V activated solid state relay can be connected directly
to pin 23 of the microcontroller (25mA drive maximum).
When in Manual mode, the relay can be turned on or off.
When in Automatic mode, the relay is turned on when the mpsas reading is above the threshold and off when the
mpsas reading is below the threshold.
Pressing the On/Off buttons while the realy is in automatic mode will switch it to manual mode.
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Unihedron SQM-LU Operator’s Manual -
20170728
Summary of Contents for SQM-LU
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