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SF33
Multi-beam laser sensor
6. Communicating with the serial port
The serial port is used to transmit distance readings to an embedded host processor such as the flight controller in a UAV. The
hardware interface uses 3.3 V logic levels and can be connected directly to any similar, compatible interface.
The distances measured by each of the three laser beams are sent out as a packet of binary coded bytes preceded by the header
values 0xFF, 0xFF. The format of each packet is shown below:
Data packet structure
0xFF, 0xFF, L1, H1, L2, H2, L3, H3
Setting
@ 1.00 m
@ 0.50 m
3: Serial port
@ 0.25 m
update rate
@ 0.03 m
@ Filter
4: Serial port baud rate
The "3: Serial port update rate" setting allows the output rate of the serial port to be set to any value within the limits imposed by
the snapshot resolution. Values will be rounded in order to give whole number divisors of 3052 and limited automatically if they are
too high for the resolution selected.
The "4: Serial port baud rate" selection toggles through all the standard baud rates from 9600 to 921600. If the baud rate is set too
low, there won't be enough time for the data to complete a transmission before the next result is ready. The Serial port update rate
is reduced if this situation occurs. Both the transmitted data and any received commands are at the same baud rate.
SF33 Multi-beam sensor - Product Manual - Revision 1
Product manual
Figure 6 :: Serial interface connections
Data format of each distance result
Byte_L, Byte_H
Values
10 ... 3052 / sec
Sets the rate at which new results are output from the serial port when it
is selected using "1. Active data port".
10 ... 1526 / sec
The actual value may be lower than the entered value depending on the
10 ... 763 / sec
setting "2: Snapshot resolution".
10 ... 95 / sec
Only whole number fractions of 3052 will give an exact match between
the entered and actual values.
10 ... 95 / sec
Selects the baud rate for the serial port. If the "3. Serial port update
9600 ... 921600
rate" setting is too high for the selected baud rate then a warning notice
will be displayed.
8
Conversion of each result to distance in meters
Distance = Byte_H + Byte_L / 256
Description
of
15
© LightWare Optoelectronics (Pty) Ltd, 2016
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