54A0059_V1.1_EN / LeddarSteer DBSD Evaluation Board
–
User Guide
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9.
First Measurements
Once the starter kit’s firmware has been updated and an operating mode has been selected, the first
measurements can be performed. As mentioned above, the serial terminal can still be used independently
of the selected operating mode. The section below will provide a quick overview of the different functions
that can be used in the serial terminal to trigger the different sub-components present in the DBSD.
To actively monitor the DBSD, simply enter the relevant commands void of any argument. Examples will be
provided in the next sub-section. For more information on the individual commands, see
section “
”
9.1.
Power Supplies
Before driving the liquid crystal cells or the ITO heaters, it is important to make sure that both the 30 V and
24 V power supplies are enabled. To do so, simply use the
“30v” and “24v”
commands and use the argument
“
1
”
to enable them. The power supplies are enabled at boot-up but using the
“
30v,
”
“
24v,
” and
“
sv
”
commands
can ensure that the DBSD is powered correctly.
9.2.
Driving Liquid Crystal Cells
The first step after having verified that the power supplies are enabled is to set the number of cells in the
DBSD. Unless otherwise specified, the DBSD will always have 8 cells. As such, use the
“
cn
”
command and
give
“
8
”
as the argument. The DC balance frequency must also be set to 2000 Hz. The
“
f
”
command must
also be used with the argument
“
2000.
”
Alongside the physical hardware, a lookup table, as well as pre-calibrated voltages, should be provided with
the evaluation kit. In fact, to allow the DBSD to steer light at a given angle with the minimum amount of
leakage, all of the low-voltage liquid crystal cells must be calibrated for every given tile. See
section “
for the laboratory setup required to complete an in-house calibration.
The most important commands to take into consideration when completing a calibration are the voltage
associated with eac
h cell for any given state ID. The “st”
command allows changing those values by simply
providing the desired state ID and the subsequent voltage per cell. To fine-tune the voltage value of every
individual cell, use the
“
cv
”
command along with the
“
s
” comm
and to allow for the modification of individual
cells in a given state ID.
The duty cycle of individual cells can also be monitored and modified through the “cdc” command.
Once the voltages have been set, the LC cell voltages can be sampled by using the
“wt” and the “wsp”
commands, which provide the waveform sampling period. The results can be seen using the “wp” command.
9.3.
Driving ITO Heaters
The DBSD performances are contingent on it being at a temperature that is higher than room temperature.
Therefore, ITO heaters are necessary to bring the DBSD to a higher temperature.
The first command should be
“
ctn 4,
”
since there are a total of four temperature sensors on the DBSD.
To automatically drive the ITO heaters from the temperature controller, use the “tc 1” command to enable
temperature control, then the operating temperature can be set through the “tcs” command. Alternatively,
the ITO heaters can be driven manually by first disabling temperature control with the
“
tc 0
” command,
then
using the
“
ito
”
command to set the power level of each heater.
To monitor the temperature from the temperature sensors
, simply use the “ct” command.