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i: Linear analog output (0.00 m to 25.00 m = 0.00 V to 2.048 V | 0.00 m to 25.00 m = 2.048 V to 0.00 V)
Menu item <i> is used to select either an analog voltage or a digital alarm output. There are four selections, two for the analog
voltage and two for the alarm. This section describes the analog voltage output. This value may also be changed using the serial port
and I2C command set.
The two analog output selections determine the polarity of the analog voltage. This voltage can be configured to increase with
increasing distance or decrease with increasing distance. The increasing voltage option is useful for measuring the height above
ground whilst the decreasing voltage option might be used to measure the clearance to a roof above the UAV.
Figure 10 :: Altitude represented by distance (Serial / I2C) and analog voltage
Item
Analog output mode
j: Analog distance range (1.00 m ... 100.00 m)
The distance at which the analog output reaches the maximum voltage can be set by selecting menu item <j>. The output voltage
can be converted back into a distance by using the formula:
where:
d = calculated distance
v = voltage measured by the ADC of the host controller
g = 2.048 V or 3.3 V scale set by menu item h.
j = the maximum distance setting entered using menu item j.
The analog voltage output updates 20 times per second and has a 12 bit resolution. For greatest accuracy, keep the distance range to
the lowest useful value for your application. Do not use the entire measuring range if it is not needed. This value may also be
changed using the serial port and I2C command set.
Item
Analog range / alarm set point
SF11 Laser altimeter - Product manual - Revision 10
HMI
Type
read
menu item <i>
analog ... alarm
write
d = v / g * j
HMI
Type
read
menu item <j>
56.78 m
write
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© LightWare Optoelectronics (Pty) Ltd, 2021
SF11 Laser altimeter
Serial
?OM<CR><LF>
?OM 3<CR><LF>
#OM,3<CR><LF>
#OM,3 3<CR><LF>
Serial
?OD<CR><LF>
?OD 56.78<CR><LF>
distance range = (a*256+b)/100
#OD,56.78<CR><LF>
#OD,56.78 56.78<CR><LF>
b = (byte)(range*100 & 0xff)
|
Product manual
I2C
.write(16)
.read(a)
mode = a
.write(17, a)
a = 0, 1, 2 or 3
I2C
.write(12)
.read(a,b)
.write(13,a,b)
a = (byte)(range*100 >> 8)
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