Optotune Lens Driver 4 User manual
Manual: Lens Driver 4
Date: 28.06.2019
Copyright © 2019 Optotune
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Electrical Lens Driver 4
Lens Driver Manual
Manual: Lens Driver 4
Date: 28.06.2019
Copyright © 2019 Optotune
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as to the reliability, completeness or accuracy of this paper.
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Table of Contents
1. Overview...................................................................................................................................................3
1.1 Integration Into OEM Systems.......................................................................................................... 3
1.2 System requirements .......................................................................................................................4
2. Hardware Operation ................................................................................................................................. 4
2.1 Connecting to a lens with FPC cable.................................................................................................. 4
2.2 Connecting the with an extension cable ........................................................................................... 4
2.3 Using the driver as current source only............................................................................................. 4
2.4 Connecting industrial-style lenses to the Lens Driver 4i..................................................................... 5
2.5 Open and Close Housing of Lens Driver 4i......................................................................................... 5
2.6 Connector Pinout............................................................................................................................. 6
3. Lens Driver Controller Software.................................................................................................................7
3.1 Software Installation ........................................................................................................................ 7
3.2 Installation of the Windows driver in Windows 7, Windows 8.1 and Windows 10..............................7
4. Preparing Lens Driver 4 ............................................................................................................................. 7
5. Operating Lens Driver Controller ............................................................................................................... 7
Controls........................................................................................................................................................ 8
5.1 Limiting the Maximum Current.........................................................................................................8
5.2 Temperature Compensation.............................................................................................................9
5.3 Achievable Range of Focal Power ..................................................................................................... 9
5.4 Drift Compensation........................................................................................................................ 10
5.5 Autofocus ...................................................................................................................................... 11
5.6 Trigger Output Signal ..................................................................................................................... 13
5.7 Lens Control by Analog Signal......................................................................................................... 13
5.8 Sensor Control ............................................................................................................................... 15
6. Communication Protocol......................................................................................................................... 15
6.1 Current Set Commands .................................................................................................................. 16
6.2 Focal Power Set Command............................................................................................................. 17
6.3 Mode Commands........................................................................................................................... 18
6.4 Calibration Commands................................................................................................................... 19
6.5 Temperature Reading..................................................................................................................... 19
6.6 CRC Algorithm................................................................................................................................ 20
6.7 Checking for Communication Error................................................................................................. 20
6.8 Adding a CRC Checksum to a Data Array......................................................................................... 20
7. UART Communication (only Applicable for EL-10-30-C Firmware Type A)................................................. 22
Manual: Lens Driver 4
Date: 28.06.2019
Copyright © 2019 Optotune
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1. Overview
The Electrical Lens Driver offers a simple yet precise way to control Optotune’s electrical lenses. There are two
types of lens drivers available. The Electrical Lens Driver 4 is used to drive Optotune’s OEM-type lenses with 6-
pin FPC cables and comes in a plastic housing. The second Lens Driver 4i is suited to drive the industrial ver-
sions with 6-pin Hirose connectors and is contained in a steel housing. The main features are:
•Current control range up to -290 to +290 mA with 12 bit precision
•Drive frequencies from 0.2 to 2000 Hz (rectangular, triangular or sinusoidal)
•I2C sensor read-out e.g. for temperature compensation
•USB powered
•Driver software in Windows 7 and Windows 8
•Available with or without housing
Mechanical specifications
Lens Driver 4
Lens Driver 4i
Dimensions (L x W x H)
77 x 19 x 13
99.05 x 19 x 13.5
mm
Weight
11
41
g
Interface to lens
0.5mm pitch 6 way FPC connector
6-pin Hirose connector
Interface to PC
USB Type A
Electrical specifications
Lens Driver 4
Lens Driver 4i
Maximum output current
-290 to 290 mA depending on resistance (see Figure 8)
Maximum output update frequency
>100
kHz
USB input voltage
5
V
Power consumption
50-1100
mW
Digital to analog converter
12 bit Analog Devices ADN8810
Microcontroller
8-bit, 16 MHz with 32 KB Flash (Atmel ATmega32U4)
Connector
6-way FPC (Molex 503480-0600)
6-way Hirose HR 10 G
Maximum cable length
3 meters 1
Thermal specifications
Lens Driver 4
Lens Driver 4i
Operating temperature
-20 to +65
°C
Storage temperature
-40 to +85
°C
1.1 Integration Into OEM Systems
Both Lens Drivers are easily integrated into OEM systems. The microcontroller that is used offers serial inter-
faces over USB and 5V UART (which can be translated to RS-232 using a MAX232 or MAX3232 chip). Also, ana-
log input from 0-5V is available on the driver PCB. Schematics and part list of the Lens Drivers are available on
request. Documentation of the firmware is presented at the end of this document. For more information
please contact sales@optotune.com.
1
5 m have been successfully tested, however the capacitance is 550 pF (I2C specification 400 pF max).
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1.2 System requirements
•Windows 7 or Windows 8.1, 32/64 bit
•Lens driver: USB 2.0 port
•uEye camera: USB 2.0 port (preferably 3.0)
2. Hardware Operation
2.1 Connecting to a lens with FPC cable
The Molex flex cable can be plugged directly into the connector of the lens driver. The copper side of the cable
has to be upwards and the black clamp has to be closed.
Figure 1: Connecting the EL-10-30-C directly to the lens driver.
2.2 Connecting the with an extension cable
If a larger distance is required, the easiest way is to use an USB extension cable for the lens driver. If a larger
distance in between the lens and the driver is required, an extension as described in Figure 2 can be built. For
large distances, shielded cables are recommended to ensure interference-free performance of the I2C bus. The
butterfly connector and the 5cm long transition cable are provided with the lens driver.
Figure 2: Connecting the EL-10-30-C with an extension cable to the lens driver.
2.3 Using the driver as current source only
On the side of the PCB, two pads are available to connect lenses without temperature sensor.
Figure 3: Connecting the compact EL-10-30 to the lens driver by soldering the plus and minus poles.
transition cable
butterfly connector
+
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2.4 Connecting industrial-style lenses to the Lens Driver 4i
The connection of the industrial EL-10-30-Ci to the Lens Driver 4i is straight forward. Simply connect the cable
to the plug, the position of the pins is unambiguous.
2.5 Open and Close Housing of Lens Driver 4i
To open the housing use the gaps on the side to spread the cover side-walls with an appropriate flat head
screw driver. Hold the enclosure base and lift the cover to open the casing:
In order to close the housing, place the cover on top of the enclosure base (a) and move it towards the USB
stick (b) until the front side clips fit in the openings of the cover. Then push the cover at the back downwards
(c) until the back side clips snap into the square holes (d). If the clips do not snap in, gently apply pressure from
the top/bottom/side to move the cover forward/backward or up/down relative to the base unit.
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2.6 Connector Pinout
Figure 4: Connector pinout of the Lens Driver 4 (left) and Lens Driver 4i (right).
Lens Driver 4
Lens Driver 4i
Position
Function
Position
Function
1
I2C Gnd
1
Lens (+ pole)
2
Lens (- pole)
2
Lens (- pole)
3
Lens (+ pole)
3
I2C Gnd
4
I2C SDA
4
I2C Vcc 3.3V
5
I2C SCL
5
I2C SCL
6
I2C Vcc 3.3V
6
I2C SDA
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3. Lens Driver Controller Software
3.1 Software Installation
•Run Setup.exe
•Follow the installation wizard
3.2 Installation of the Windows driver in Windows 7, Windows 8.1 and Windows 10
Please follow the instructions below to install the Windows driver for the Optotune Lens Driver
•IMPORTANT: Please disconnect any lenses from the Lens Driver hardware!
•Connect Lens Driver to a free USB port on your PC.
•Windows will now try to install a driver. This process won't succeed because of a missing driver soft-
ware. This can be ignored.
•Open Windows "Device Manager”.
•Windows 7, 8, 8.1
In "Device Manager" navigate to the category "Other devices", right click on the device "Optotune LD"
and select "Update Driver Software...".
Windows 10
In "Device Manager" navigate to the category "Ports (COM & LPT)", right click on the device "USB Seri-
al Device (COMX)" and select "Update Driver Software...".
•Select "Browse my computer for driver software".
•Click on "Browse" and navigate to the directory where you installed the Lens Driver Controller applica-
tion (usually C:\Program Files (x86)\Optotune AG\Lens Driver Controller). Confirm the folder choice by
clicking "OK".
•Make sure "Include subfolders" is checked and click "Next".
•Click "Next" in the "Update Driver Software" window.
•The installation proceeds and installs the Windows driver.
•The Windows driver is successfully installed if you see a device called "Optotune Lens Driver powered
by atmel" in the section "Ports (COM & LPT)" within the "Device Manager".
4. Preparing Lens Driver 4
In order for the Lens Driver 4 to operate correctly, a product specific firmware needs to flashed. Please refer to
the manual of the Lens Driver Flash Utility on how to flash the firmware. The following list gives an overview of
the different firmware types.
Firmware Type
Compatible Lens
A
EL-10-30-C series
F
EL-10-30-TC series, EL-16-40 series
5. Operating Lens Driver Controller
Launch Optotune Lens Driver Controller and click on Connect. This will establish the hardware connection and
open the main window with the current control and the temperature readout.
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Controls
Figure 5 shows the main window. The output current can be changed, either by shifting the arrow or by using
the +/- buttons. Using the +/- buttons together with the Shift key increases the step size. Alternatively, the
desired value can be written in the gray box.
Figure 5: Screenshot of the main window of the Lens Driver software with the current control.
The drive signal can be chosen to be a DC, sinusoidal, rectangular or triangular
2
signal with the possibility to set
the upper and the lower signal level as well as the driving frequency. This is indicated in Figure 6.
Figure 6: The drive signal can be chosen to be a DC, sinusoidal, rectangular or triangular2signal.
5.1 Limiting the Maximum Current
The limits for the current are set in the Hardware tab, shown in Figure 7.
Figure 7: Setting the current limits.
2
FW Type A only
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The maximum current of the driver is limited to either 290mA, see Figure 8, or 2.8V divided by the resistance
applied.
Figure 8: Dependence of maximum current on coil resistance.
5.2 Temperature Compensation
When heating up the lens, the fluid expands in volume and therefore, the focal length of the lens decreases.
The focal length decreases linearly by approximately 0.2 to 0.7 diopters per 10°C temperature increase, de-
pending on the lens model. This temperature effect is systematic and reproducible and is therefore accurately
compensated via a temperature sensor SE97B with an I2C sensor read-out, integrated in the lens (except in the
EL-3-10). This allows controlling the focal power directly.
In Focal Power mode, see drop down menu in Figure 6, temperature independent lens operation is ensured.
Depending on the present temperature, the current applied to the lens is adjusted for compensation of the
temperature drift. A look-up table with the calibration data for the temperature compensation are stored di-
rectly on the EEPROM of each individual lens. With the temperature compensation enabled, the absolute re-
producibility achieved over an operating temperature range of 10 to 50°C amounts to typically 0.05 or 0.1 diop-
ters for the EL-16-40-TC and EL-10-30-TC series, respectively.
5.3 Achievable Range of Focal Power
If the focal power is outside the guaranteed diopter range then a warning message will appear in yellow “warn-
ing focal power outside guaranteed range” and the panel has a yellow background, see Figure 9. The user can
then change the focal power until the displayed focal power no longer has a yellow color and is within the
guaranteed diopter range.
Figure 9: On the left, the focal power is outside the guaranteed range and the panel is yellow. On the right, the
focal power is within the range.
The limits for the range of focal power are determined by the temperature limits and the maximum and mini-
mum current. The maximum diopter limit is located at highest encoded temperature limit and maximum cur-
0.0
50.0
100.0
150.0
200.0
250.0
300.0
0 5 10 15 20 25 30
Maximum current
Coil resistance
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rent and the minimum diopter limit is located at the lowest encoded temperature and the minimum current.
This is explained in Figure 10. The highest and lowest temperature define a sector for the linear relation of focal
power versus current, indicated by the light and dark gray line. The values are adjustable in File →Options
under Temperature Settings. The colored line represents the diopter range at the current temperature be-
tween the highest and lowest temperature, with the colors representing the following states:
•Green: Focal power can successfully be maintained at predefined temperatures limits in this range.
•Yellow: Focal power can be maintained at the current temperature and/or current drift state.
•Red: Focal power cannot be maintained at the current temperature and/or drift state.
The minimum green/yellow limit is determined by the diopter value at the highest temperature and minimum
current. The maximum green/yellow limit is determined by the diopter value at the lowest temperature and
maximum current. Both limits are indicated by the dashed horizontal lines in Figure 10. The closer together the
minimum and maximum temperature limits are, the larger the guaranteed range (green) will be. In addition,
the yellow/red limits are determined by the diopter values at min/max current at the current temperature.
Figure 10: Illustration of the achievable range of focal power (vertical axis) versus current (horizontal axis). The
guaranteed range (green line) also depends on the highest and lowest temperature, indicated by the gray lines.
5.4 Drift Compensation
When set to a certain focal power the lens shows a tiny drift over timescales of about 5min. If a highly stable
focus position over long times is required, using the implemented drift compensation is recommended. To do
so the Drift Compensation Gain, found under Hardware (see Figure 7) has to be set by the user to a finite value,
typically 1, otherwise no compensation is taking place. Higher values increase the gain up to a maximum value
of 5. Internally, two parameters Driftmax and Driftcurrent are affected by the Drift Compensation Gain, as dis-
cussed in the following.
When finite drift compensation is set it also scales the achievable diopter range. Figure 11 illustrates the effect
that drift compensation will have on the achievable diopter range. First, compared to Figure 10, the yellow/red
boundaries in Figure 11 are shifted upwards due to a finite current drift (Driftcurrent). As a consequence the
achievable diopter range is also shifted upwards by a small amount. Second, the maximum drift Driftmax set by
the drift compensation is added to the minimum guaranteed diopter limit, which is represented by the lower
Focal Power (m-1)
Current (mA)
Highest Temperature
Lowest Temperature
Currentmin
Dioptermax
Dioptermin
Currentmax
Diopter Range
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yellow/green boundary, and therefore slightly reduces the guaranteed diopter range. The maximum drift is
determined by the gain variable and a larger gain variable will result in a larger maximum drift.
For lenses with a small focal range the effect of increasing the gain variable to high values (e.g. 3 or higher) can
be that the achievable diopter range is too small such that focal power cannot anymore be changed by the
user. In that case the gain variable has to be reduced.
A visual representation of the overall achievable focal power range as shown on the focal power scroll bar in
the software can be found in Figure 12.
Figure 11: Illustration how drift compensation affects the achievable range of focal power.
Figure 12: Overall achievable diopter range as shown on the focal power scroll bar.
5.5 Autofocus
Focal Power (m-1)
Current (mA)
Highest Temperature
Lowest Temperature
Currentmin
Diopter
max
Currentmax
Diopter Range
Driftmax
Dioptermin
Driftcurrent
Driftcurrent
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When using the Lens Driver in combination with a uEye camera, it also offers an autofocus feature. Please note
that this feature is for testing purposes only and Optotune does not offer support for this part of the software.
The autofocus software is only tested yet with the camera model IDS UI-3580CP-C-HQ. To use the autofocus, go
to Extras → uEye Viewer. The uEye viewer window will open.
Settings:
In Lens driver →Auto Focus Settings, the settings can be adjusted to optimize the autofocusing. The parameter
shown in Figure 13 are standard values that work for most applications. In order to optimize e.g. the time it
takes to autofocus one may set the thresholds for coarse, mid and fine scanning closer to 1, but the values
have to be Coarse < Mid < Fine. The check box to enable auto switch to focal power acts only if a lens with
stored calibration data on the lens’s EEPROM is used. Camera settings like frame rate and exposure time can be
changed in Camera →Settings. Autofocus only works reliably if the image is bright enough.
Figure 13: Settings for the Auto Focus option in combination with a uEye camera.
For autofocus, click on the image in an area that contains structures with reasonable contrast. The current
applied to the lens is then automatically adjusted and the image is in focus, as in Figure 14.
Figure 14: Autofocus is achieved by clicking on the image
Options:
Pixel-to-pixel modus: in the ‘pixel-to-pixel’ modus, the resolution is chosen in the way that one pixel of the
image corresponds to one pixel of the screen.
Switch modus: In this modus, the driver switches between two current values with a rectangular driving signal.
The lower and upper current level can be determined in the following way. First perform autofocusing for the
lower level (click on the part of the image which should be in focus) and afterwards click on the lower limit
auto exposure
auto whitebalance
enables maximal camera resolution
switch modus
zoom
pixel-to-pixel
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button (arrow with an underline). Repeat the steps for the upper limit (arrow with an over line). If you than
enable the button with the two arrows, the current will switch between the two values. The frequency is
changed in the Controls window.
5.6 Trigger Output Signal
For sinusoidal, triangular and rectangular drive signals, hardware pin A (see Figure 15) outputs a trigger signal
which can be used to synchronize the lens driver to another hardware component. The synchronization output
signal toggles between 0 V and 5 V and provides a maximum of 15 mA. Please note that the pin “Analog In A”
has been re-configured from an analog input to a digital output (trigger output).
Figure 15: Hardware pin A for trigger output signal.
The relation between the trigger output signal and the corresponding output signal of the Lens Driver for dif-
ferent drive signals are shown in Figure 16:
Figure 16: Relation between trigger and output signal for different drive signals.
5.7 Lens Control by Analog Signal
The lens current can be controlled by the analog signal reading feature, which is built into the firmware. The
analog voltage applied on hardware pin B (see Figure 17) must be between 0 V and 5 V. The ADC has a resolu-
tion of 10 bit and therefore the digital signal value lies between 0 and 1023. The applied voltage and therefore
the 10 bit value is then linearly mapped in firmware to the range defined by the lower and upper software
limits in the Hardware Configuration (see Figure 18) tab of Lens Driver Controller. These limits are persisted in
the firmware configuration and are reloaded when the lens driver is powered up (Lens Driver Controller is not
required to run for this). In analog mode (see Figure 19), the Lens Driver autonomously and continuously maps
the analog value to the corresponding current value applied to the lens.
Note that in this stand-alone analog mode the analog value is only mapped to current and thus no automatic
temperature compensation is possible. The next section explains how the analog value can be mapped to opti-
cal power by going through the Lens Controller Software.
Figure 17: Hardware pin B for analog input signal.
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Figure 18: Hardware Configuration (example shows mapping between -100mA and 150mA)
Figure 19: Analog mode enabled in Lens Driver Controller
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5.8 Sensor Control
Through an analog signal that is read by the lens driver, an ex-
ternal voltage from an analog sensor can be used to control the
focal power of the lens. Sensor control can be used in either
Current or Focal Power mode, and is enabled under Services ->
Sensor Control.
To enable this functionality, a set of calibration points must first
be inputted. A calibration point consists of an analog input value
set by a sensor and a desired current/focal power value. If sensor
control is enabled, the software will linearly interpolate between
the configured points, and set the current/focal power according
to the analog input. It is important to note that sensor control
will only be enabled if at least two calibration points have been
defined. Calibration points can be stored using the sensor control
configuration form found under Extras -> Sensor Control Config-
uration. The points are stored in a modifiable table, and are
saved in the software for future use. The screenshot below rep-
resents the sensor configuration form in Current mode.
Button Functions:
•Record Entry: Store the latest analog input and current/focal power value as a calibration point.
•Add Row: Create an empty row in the configuration table to manually input a calibration point.
•Delete Row: Every row with a highlighted cell will be removed from the table.
•Save Table: Save the configuration table. Note that sensor control will only work if at least two calibra-
tion points have been saved.
•Quit: Exit the sensor control configuration form. Users will be prompted to save any unsaved data.
6. Communication Protocol
This section describes the protocol used to control the lens driver in case customized software is written. The
protocol can be implemented using any programming language. An example for the CRC calculation is only
given in C.
The documentation shows commands sent out by user software (i.e. PC) and the answer to be expected as a
response from the driver as well as the action that is taken by the driver as a result of the command. Com-
mands in quotes (“) have to be sent as a string (or char array) with each letter representing one byte except for
“\r” meaning “carriage return”, “\n” meaning “new line” and are represented by a single byte (ASCII code).
Letters in red are sent as ASCII characters and letters in blue are coded as binary bytes.
While this section describes the protocol for the main commands used to control the lens driver, detailed in-
formation on other commands can be found in the command protocol file which is available on request.
Connection:
The Microcontroller used runs a virtual com port driver provided by Atmel. The connection settings are:
•Baudrate: 115200 (others may also work since the port is virtual)
•Parity: None
•Stop Bits: One
•Data Bits: 8
Handshake:
The handshake command is used to check if the hardware is ready and running. It can also be used as a reset
function as it will reset the current to zero. Other commands are also valid without sending this command after
initialization, it is optional.
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PC sends
Driver answer
Driver action
Comment
"Start"
"Ready\r\n"
reset current to zero, flush input buffer
optional command
6.1 Current Set Commands
A current set command sets a new output current for a channel. A current set command is constructed as
AwxxLH. It always starts with the channel identifier "A" for channel A
3
, and the write identifier char “w”. The
current sent out (io) is coded as a 12bit value (xi) that is mapped to the maximum hardware current range (ic).
The maximum hardware current range (calibration value ic) can be read and written from the driver, see sec-
tion about calibration commands. By default, ic =293mA. The formula to calculate the value xifor a certain
current is:
xi= io/ ic* 4096
Example for a current of 50mA for a calibration value of 293mA:
50mA / 293mA * 4096 = 699
Commands to set current are sent as one char selecting the channel, followed by two bytes containing the
16bit signed current value xi[-4096 to 4096], followed by two bytes for the CRC16 checksum which is calculat-
ed over all the preceding data bytes (see CRC16 code section on how to implement it) with the low byte of the
CRC sent first: “LH” means ‘Low Byte’, ‘High Byte’. If a value is out of boundaries (i.e. 5000) it is limited to 4096
by the firmware, no overflow will occur. If the software current limit is set lower than 4096 (i.e. 3000, see cali-
bration commands), current requests bigger than the software limit will be reduced down to the limit (i.e.
3000). The driver does not reply to correctly received current commands to make the possible update rate as
fast as possible. Invalid commands (i.e. incorrect CRC) will be answered with “N\r\n”.
Char coding for the current set command:
"A"
Channel A
“w”
Write Identifier
PC sends
Driver answer
Driver action
Comment
"AwxxLH"
none
set channel A
current to xx
xx is a signed 16bit integer with a value between -4096 and 4096, high
byte sent first
"AwxxLf"
”E1”<crc>“\r\n”
none
Here we simulate an error, passing a wrong CRC value. f = error in CRC
byte, this line applies for all detected CRC errors. For all the error codes
refer to the structure protocol.
Exemplary current set command
Command type: Set current
Channel: A
Current value: 1202
Resulting command:
Byte 0: 0x41 (corresponds to ASCII "A")
Byte 1: 0x77 (corresponds to ASCII "w")
Byte 2: 0x04 (high current byte) / 0b00000100
Byte 3: 0xb2 (low current byte) / 0b10110010 -> with byte 2 the total current bits are
0b0000010010110010 which equals to 1202 dec
Byte 4: 0x26 (low CRC byte)
Byte 5: 0x93 (high CRC byte)
3
Currently, the Lens Driver only hosts one channel. In future, a second channel might be added to control two lenses simultaneously.
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Optotune AG | Bernstrasse 388 |CH-8953 Dietikon |Switzerland
For verification of the command, the CRC checksum (see details below) over the whole 6 bytes of the command
can be calculated which should be zero.
6.2 Focal Power Set Command
A focal power set command sets the focal power of the lens. The command starts with the prefix “P”, followed
by the write identifier “w”, the coding char “D”, and the channel identifier “A”. The command then includes 2
bytes for the desired focal power value and 2 dummy bytes. The focal power value has a firmware type specific
encoding.
Firmware type A (EL-10-30):
xi= (fp +5) *200
Firmware type F (EL-16-40):
xi= fp *200
Example for setting a focal power of 5 diopters in type A firmware:
(5 + 5) * 200 = 2000
Similar to current set commands, the command is finished by a 16bit CRC calculated from the eight command
bytes. The low byte of the CRC is sent first. It is important to note that this command will only work in con-
trolled mode (see Mode Commands below).
Char coding for the focal power set command:
"P"
Prefix
“w”
Write Identifier
“D”
Coding
"A"
Channel A
PC sends
Driver answer
Driver action
Comment
"PwDAxxYYLH"
none
set focal power of
lens through
channel A
xx is a signed 16bit integer, high byte sent first. YY are 16 dummy bits.
For the usable limits of the signed 16bit integer please refer to reply
command that is sent when setting Focal Power Mode
"PwDAxxYYLf "
”E1”<crc>”\r\n”
none
Here we simulate an error, passing a wrong CRC value. f = error in CRC
byte, this line applies for all detected CRC errors. For all the error codes
refer to the structure protocol.
Exemplary focal power set command
Command type: Set focal power
Channel: A
Focal power value: 2000 (5 diopters)
Resulting command:
Byte 0: 0x50 (corresponds to ASCII "P")
Byte 1: 0x77 (corresponds to ASCII "w")
Byte 2: 0x44 (corresponds to ASCII "D")
Byte 3: 0x41 (corresponds to ASCII "A")
Byte 4: 0x07 (high focal power byte) / 0b00000111
Byte 5: 0xd0 (low focal power byte) / 0b11010000 -> with byte 1 the total current bits are 0b
0000011111010000 which equals to 2000 dec
Byte 6: 0x00 (required dummy byte)
Byte 7: 0x00 (required dummy byte)
Manual: Lens Driver 4
Date: 28.06.2019
Copyright © 2019 Optotune
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Byte 8: 0x31 (low CRC byte)
Byte 9: 0xfd (high CRC byte)
6.3 Mode Commands
Mode commands allow to access frequency modes (see table). A mode change command always starts with
"M", followed by a "w" to write the command. Reading commands back is by sending an “r” instead of a “w” is
possible but not tested and recommended. The “w” is followed by a char identifier that selects the mode type
(“S”, “Q”, “T”,”C” or “D”, see table) and finally a char selecting the channel (“A”). The command is finished by a
16bit CRC calculated from the four command bytes. The low byte of the CRC is sent first.
To set the property of the selected mode (i.e. frequency and currents) a signal property change command is
used. This command starts with a “P” followed by a “w” to write the command. Again, reading commands back
is by sending an “r” instead of a “w” is possible but not tested and recommended. The “w” is followed by a char
identifier that selects the property to be changed (“U”, “L” or “F”, see table). Next a char selecting the channel
(“A”) is sent. The next four bytes sent represent the data for the command. It is a 32-bit unsigned integer for
the frequency or a 16bit signed integer followed by two dummy bytes for the current. The frequency needs to
be multiplied by 1000 (fixed comma representation). Example: For a frequency of 12Hz the integer sent out
needs to be 12000 (0x00002EE0 as a 32bit hex). The bytes to be sent out (in this order) are: 0x00, 0x00, 0x2E,
0xE0. The command is finished by a 16bit CRC calculated from the eight command bytes. The low byte of the
CRC is sent first.
The mode “C”, or Controlled Mode, allows the driver to maintain the focal power of a connected lens. This
mode must be enabled in order to use focal power set commands.
Char coding for the mode change command:
"A"
Channel A
“w”
Write Identifier
"S"
Sinusoidal signal
"Q"
Square signal
"D"
DC signal
"T"
Triangular signal
“C”
Controlled Mode
Char coding for the signal property change command:
"U"
upper swing current [-4095 to 4095]
"L"
lower swing current [-4095 to 4095]
"F"
Frequency (in ‘value in [mHz] = value in [Hz] *1000’ )
Mode command examples:
PC sends
Driver answer
Driver action
“MwSALH”
"MSALH\r\n"
set channel A to sinusoidal waveform
“MwCALH”
"MCAsBBCCLH\r\n"
set channel A to focal power controlled mode. The byte s is a
status byte #1 (refer to “Communication Protocol” Excel file), BB
is a 16bit signed integer max focal power, and CC is a 16bit
signed integer min focal power. The focal power values fp can be
calculated from the sent integers xiby using the following formu-
la (depending on firmware type):
Firmware type A (EL-10-30):
fp = xi/200 - 5
Manual: Lens Driver 4
Date: 28.06.2019
Copyright © 2019 Optotune
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as to the reliability, completeness or accuracy of this paper.
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Firmware type F (EL-16-40):
fp = xi/200
„PwFAyyyyLH“
nothing
set channel A frequency to yyyy (in mHz, 32bit value)
„PwUAyyddLH“
nothing
set channel A upper signal current to yy (12 bit value)
(dd are two dummy stuffing bytes and can be 0)
Setting focal power mode sends a command back containing the usable limits for the focal power values.
6.4 Calibration Commands
Calibration commands are used to set and read calibration values and software current limits. These values are
stored in the EEPROM, a non-volatile memory, and are kept there for years.
Software current limits can be set to protect a lens from overcurrent or to fix the maximum focal power. Limits
also apply in analog input mode.
Note: in analog input mode the input voltage 0-5V is mapped to [-4095 to 4095] in a 10bit resolution.
Software current limits apply.
A calibration command always starts with "C" followed by "r" to road or "w" to write the command value. The
next byte determines the type of value. It can be “M” for the maximum current calibration value (in [mA*100]),
“U” for the upper software current limit or “L” for the lower software current limit. Next a char selecting the
channel (“A”) is sent followed by two data bytes (16-bit integer). The maximum current calibration value is the
output current measured for the xi= 4095 value and does normally not need to be changed as design guaran-
tees 1% accuracy to the default value. The default value is 29284 (292.84mA).The software current limits are
sent as a 12bit current value and can also be negative like a normal current command. As usual the command is
finished by a 16bit CRC calculated over the seven command bytes.
Note: the upper and lower limits are always saved to EEPROM that allows "only" 100'000 write cycles
before it starts wearing out. There is no limit on reading.
Char coding for the Calibration command:
"A"
Channel A
"M"
Maximum hardware current [mA]*100 (calibration value)
"U"
Upper software current limit [-4095 to 4095]
"L"
Lower software current limit [-4095 to 4095]
Calibration command examples:
PC sends
Driver answer
Driver action
Comment
"CrMAddLH"
"CMAyyLH\r\n"
none
read channel A calibration, "dd" are two dummy bytes and can be 0
"CwLAxxLH"
"CLAxxLH\r\n"
write xx as new lower
limit of channel A
limit is immediately active, answer is for double checking
"CrUAddLH"
"CUAyyLH\r\n"
none
read channel A upper current limit, "dd" are two dummy bytes and can be
0
6.5 Temperature Reading
If the lens connected supports temperature reading, this command will read back the temperature of the inte-
grated sensor (NXP SE97B). To convert the value to a temperature the following formula can be used:
Temperature [°C] = data * 0.0625 [°C]
For more details about the conversion please refer to the datasheet of the temperature sensor.
The temperature read command starts with a “T” followed by the channel selection byte (“A”). The command
is completed with the 16bit CRC calculated over the two command bytes. Low CRC byte is sent first.
Manual: Lens Driver 4
Date: 28.06.2019
Copyright © 2019 Optotune
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No representation or warranty, either expressed or implied, is made
as to the reliability, completeness or accuracy of this paper.
Optotune AG | Bernstrasse 388 |CH-8953 Dietikon |Switzerland
Possible temperature commands:
PC sends
Driver answer
Driver action
Comment
“TCALH”
“TCAddLH\r\n”
Get temperature reading
of lens on channel A
“dd” is the temperature data as 16 bit signed integer.
6.6 CRC Algorithm
A 16-bit CRC checksum (CRC-16-IBM) is used to check for communication errors. The code examples below use
the reverse polynomial implementation.
•Reverse polynomial: 0xA001
•Initial value to be used: 0x0000
6.7 Checking for Communication Error
Checking for a communication error is done by calculating the CRC checksum over the whole command data
array which includes two CRC bytes at the end that were added from the sender. CRC checksum calculation
over the whole array results in a CRC checksum equal to zero if no data corruption is present.
The following example shows the checkcrc implementation in the Lens Driver firmware, which is written in C:
/* Example usage of the CRC function */
// Example: Set current level to 1202 command sent from PC (includes CRC bytes)
// With this data array the returned uint16_t crc checksum will be zero
// (0x00) since no communication error has occurred.
// uint8_t data[] = { 0x41, 0x77, 0x04, 0xb2, 0x26, 0x93 };
uint16_t calculatecrc(void)
{
uint16_t crc = 0, i;
for (i = 0; i < sizeof(data) / sizeof(data[0]); i++)
{
crc = crc16_update(crc, data[i]);
}
return crc; //returns checksum over all elements
}
uint16_t crc16_update(uint16_t crc, uint8_t a)
{
int i;
crc ^= a;
for (i = 0; i < 8; ++i)
{
if (crc & 1)
crc = (crc >> 1) ^ 0xA001;
else
crc = (crc >> 1);
}
return crc;
}
6.8 Adding a CRC Checksum to a Data Array
In order to add a CRC checksum to a data array
1. Calculate CRC checksum over data array
2. Append the calculated CRC checksum at the end of the data array
Example:
uint8_t dataarray[3] = {data byte 0, data byte 1, data byte 2}
uint8_t dataarraywithcrc[5] = { data byte 0, data byte 1, data byte 2, crc&0xFF,
crc>>8}
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