AstroLink 4 micro User manual

AstroLink 4 micro - astrojolo.com
AstroLink 4 micro
astrojolo.com 2023
WARNING!
Do not connect or disconnect the stepper motor when the power is on.
It may damage the stepper motor controller.
Before changing the stepper motor type make sure
the stepper holding current is set to 0%.
1

AstroLink 4 micro - astrojolo.com
Main features
● can be stacked with 7-port USB 3.0 hub model Y-3184
● focusing motor controller compatible with Moonlite,Robofocus motors, or any generic unipolar or bipolar
stepper motor
● 1/8 and 1/32 microstepping control with 2.0A maximum current and 1.4A maximum continuous hold current
● advanced temperature compensation with scripting support and compensation calculator
● permanent focuser position – no need to park focuser after the session
● 2 adjustable PWM power outputs to control dew heaters, telescope fans, or custom Peltier coolers. The
maximum load is 40W per output
● 3 switchable power outputs to power mount, cameras, or filter wheels. The maximum load is 5A per output
● 2 additional permanent power outputs - one dedicated to the USB hub (Y-3184 type recommended)
● XT60 high current input voltage socket
● temperature/humidity/sky temperature sensors to monitor environmental conditions and calculate the dew
point. It is also used for the automatic control of dew heaters
● sky brightness sensor available
● monitor voltage, current consumption, and total energy consumed during the session – useful when
working in the field with a battery
● user-defined alerts for voltages, current, energy, and temperature changes conditions
● programmable overcurrent and overvoltage protection
● dedicated AstroLink 4 panel software, ASCOM drivers available (Focuser, Switch, Observing Conditions,
Safety Monitor), INDI driver available
Technical data
● dimensions: 155x50x25mm
● weight:115g
● the maximum current drawn from all outputs: 10A
● AstroLink power consumption: 2W max
● regulated PWM outputs: 40W max
● permanent 12V DC outputs: 5A max
● switchable 12V DC outputs: 5A max
● focuser stepper motor outputs: RJ12 6 pin, 2.0A max
● sensor input: RJ11 4 pin I2C digital interface
● auxiliary input: RJ11 4-pin input
2

AstroLink 4 micro - astrojolo.com
Device overview
PWM outputs
AstroLink 4 micro has two RCA outputs that provide PWM (pulse width modulation) regulated voltage. Regulations
cover the full 0-100% range. These outputs are usually used for powering dew cap heaters. Output can be
regulated using both controls in the dedicated panel software and 3rd party software that supports the ASCOM
Switch interface or INDI interface.
Switchable 12V DC outputs
The device contains three switchable DC outputs that may provide a supply voltage for imaging setup components
(camera, mount, etc.). Output can be switched using both controls in the dedicated panel software and 3rd party
software that supports the ASCOM Switch interface or INDI interface.
Focusing motors control
The focusing motor can be controlled with AstroLink 4 micro. The output receptacle is 6 pins RJ12 socket. It
supports 12V unipolar motors with gearboxes and bipolar motors at 1/8 and 1/32 microstepping. The focusing
motor can be controlled with dedicated panel software and via ASCOM Focuser or INDI interfaces.
Permanent 12V DC outputs
These outputs are connected directly to the input 12V XT60 socket (via internal fuse and power monitor). Can be
used to provide power to a mini PC, USB hub, or other device powered with 12V.
Sensors
AstroLink 4 micro has two equivalent sensor inputs, so you can plug any available sensor into any socket and it will
be recognized and properly assigned. Connecting more than one sensor (additional sky temperature and/or sky
brightness) requires an additional sensor signal splitter. Sensor readings are available in the dedicated panel
software and via ASCOM Observing Conditions and INDI interfaces.
WARNING!
Do not connect or disconnect the stepper motor when the power is on.
It may damage the stepper motor controller.
Before changing the stepper motor type make sure
the stepper holding current is set to 0%.
3

AstroLink 4 micro - astrojolo.com
External view
1. permanent 12V DC output (dedicated for Y-3184 USB 3.0 hub)
2. permanent 12V DC output
3. switchable 12V DC outputs
4. 0-100% regulated heaters outputs
5. USB 2.0 input
6. firmware update button
7. focuser motor output
8. sensors input
9. AUX input (hand controller)
10. power LED
11. 12V DC input
4

AstroLink 4 micro - astrojolo.com
There are four M3 threaded holes in the AstroLink 4 micro device bottom. These holes can be used to attach
mounting plates or brackets to the device. Holes separation is 80x20mm.
WARNING!
Mounting screws cannot go deeper than 5mm to the AstroLink 4 micro enclosure.
Using longer screws may damage the device!
5

AstroLink 4 micro - astrojolo.com
USB hub connection
AstroLink 4 micro is designed to work together with USB3.0 hub model Y-3184. The external dimensions of this 7
port USB hub and AstroLink 4 micro are the same, and the power and USB receptacles are aligned, so the hub and
AstroLink 4 micro can be stacked into one device.
The hub may be added by the customer or can be ordered together with the AstroLink 4 micro device. In this latter
case, AstroLink 4 micro and hub are connected permanently, and also there is a DC power connector and short
USB cable included in the set.
6

AstroLink 4 micro - astrojolo.com
Software panel overview
AstroLink 4 micro panel contains several control sections. Most of the area is occupied by different controller
sections, which will be described later on. Below the control section, several other controls are available.
Stay on top checkbox makes the AstroLink panel not go to the background when another application is selected.
Buzzer checkbox controls buzzer activity.
Menu
A small cogwheel menu contains shortcuts to all other settings menu windows, so they can be also opened from
here. There is one additional position in this menu:
●Manual control. You need to check this field when you have connected the manual control box to the
AstroLink device
●Compensation calculator. This option opens an additional popup window with the compensation calculator.
See the Compensation calculator section for details
●Reset device to factory defaults - this option will reset all device settings to factory default values. The
confirmation window will be opened.
●Settings Load.../ Save... - these options allow us to save or load all device settings and configurations. All
settings, labels, initial PWM, and power output values can be stored.
Status bar
The status bar displays several different pieces of information that are visible depending on the context. It is a
read-only field.
7

AstroLink 4 micro - astrojolo.com
Charts and notes
Notes panel - after clicking on this button a small editor will pop up, where you can note down some information
you need during the imaging session (like focuser positions, flat images exposure time, etc.). Its content is saved
dynamically.
Charts button opens an additional window with AstroLink charts. See the AstroLink charts section for details.
Logo icon
After clicking on the logo icon a small information window will pop up. It contains information about firmware and
software versions.
Connection controls
The panel communicates with the device via the ASCOM driver. After clicking on that button a popup window
opens, where all applicable ASCOM drivers are listed and you need to select the proper one.
After choosing the desired driver and clicking OK the actual driver setup window opens, where you need to select
the serial port where the device is connected and other parameters. You may also test the selected serial port if the
communication to the device is correct.
After that, you may connect to the device using the Connect button.
8

AstroLink 4 micro - astrojolo.com
There are two more tabs available for the ASCOM driver. There you can adjust sky temperature cloud coverage
mapping points that correspond to clear sky and maximum cloud coverage, and set names for DC and PWM
outputs that will be visible in ASCOM Switch client software.
Connection status
Small indicator field with selected driver and light. Gray means not connected, green means connected, and red
means active communication.
9

AstroLink 4 micro - astrojolo.com
Focuser section
The focuser position in mm is calculated based on the focuser position in steps and step size defined
in settings.
The coarse relative movement factor can be set in settings between 2 and 10.
The motor status icon may be in three colors: red means the motor is rotating, yellow means the motor is idle but
holding current is applied, and green means idle and no holding current is applied.
Temperature compensation and focuser settings are described below.
Max. focuser position - here you need to enter the maximum focuser position, so the focuser will not
move to any larger value. This is to prevent any mechanical damage to the focuser.
Step size [um] - this value is stored in the driver and can be provided to any 3rd party software when
requested. It is not used internally in AstroLink.
Reversed - you can check this box when selecting the proper behavior of the focuser, so decreasing the
focuser position will cause the focuser tube to move into the telescope
10

AstroLink 4 micro - astrojolo.com
Backlash [steps] - this is for focuser motor backlash compensation. You may enter here the backlash
value that will be applied to focuser moves to cancel the stepper motor gearbox backlash. This value
may be positive or negative. A positive value means, that backlash compensation will be applied to
outward moves, and a negative value will be applied to inward moves. This compensation is applied
only when the motor is controlled with the AstroLink panel's button. When you use 3rd party
software for focusing (FocusMax, MaxIm DL, and others) use this software for backlash compensation!
Display motor graphics – toggles displaying stepper motor status icon
Preset – select any of the predefined settings for common motor parameters. Other fields in this tab
will be filled with values, but settings will be saved after the Save button is pressed.
Speed [pps] - focuser stepper speed in pulses per second. You need to select the appropriate value,
so the focuser will move with reasonable speed, but no steps will be lost during the move. For
popular unipolar stepper motors with a 7.5-degree step, it should be usually no more than 120-150.
Bipolar steppers with a 1.8 degree step usually can operate at a faster rate, up to 400-500pps. Microstepping can
operate at rates up to 2000pps.
Acceleration [s] - each time stepper starts to move, it accelerates to the speed selected in the field
Speed. Here you can enter the acceleration time. So for example, when you enter here one second,
then the stepper motor will reach its maximum speed within one second. This value is also used for
manual stepper control, but acceleration is divided by 5 for this purpose, so it is possible to do small
manual corrections.
Motor current [mA] – this is the current limit set to the motor. Refer to your motor technical data to
set proper current. For 12V unipolar geared motors offered in shop.astrojolo.com set it to 400mA or
use preset.
Hold torque [%] - when this is selected to any value greater than zero, the stepper motor will be
powered when stopped. It can then provide additional holding torque to your focuser, however
more current will be drawn, and motor temperature will increase. Make sure the stepper motor you
use is designed to be powered constantly if you want to use this option.
Stepper type - can be selected between Unipolar (like Robofocus compatible) or Bipolar motor full or
half step motors. It can be also a bipolar motor controlled with micro-steps – two options 1/8 and 1/32
stepping are available.
Enable compensation - switch compensation on or off
Compensation steps [steps/C] - this is the number of steps the focuser will move when the
11

AstroLink 4 micro - astrojolo.com
temperature will change from the initial value. So if you put here 35 and the temperature will drop
2C, then the focuser will move 70 steps (outwards). This value usually must be determined
practically, so you can note focuser positions over long night sessions together with corresponding
temperatures, and then calculate this coefficient
Auto compensation threshold [steps] - when compensation mode is set to AUTO and the calculated
compensation error will exceed this value, then compensation will be automatically applied
Compensation sensor - here you can select the sensor that will be used for temperature
measurements for focuser compensation
Compensation mode. When set to MANUAL the calculated compensation will be displayed in
the Compensation difference window, however, no compensation will be performed - it must be
triggered manually with the Compensate button (or using script - see Temperature compensation
section). When this option is set to AUTO then manual compensation will still work, but it will also be
performed automatically each time when calculated compensation error will exceed the Auto
compensation threshold value
Set focuser position - you can set any desired focuser position to calibrate it. Usually, it will be used to
set a zero position. For this case you need to move the focuser tube inwards as much as possible,
then enter the 0 value into the field and press the Set position button
12

AstroLink 4 micro - astrojolo.com
PWM section
PWM output value can be set between 0 and 100%. HEAT option controls value automatically based
on current relative humidity. The AUTO option controls value automatically to keep Sensor #2 at a given
temperature.
The first tab Labels contains labels for each PWM output, so it can be set for example to 'OTA dew
cap' or 'Guider cooling'. Another two select boxes determine the startup state of PWM outputs. Any
value set here will be set up to PWM output after the power is on.
The second tab Automated contains parameters used when the HEAT or AUTO option is selected for
PWM output:
Heat power at max humidity [%] – select here the heating power when relative humidity reaches
100%. If your heater has the correct power you may enter here 100%. But when your heater is oversized,
you may put here a lower value.
Temperature preset [C] - PWM output power will be adjusted to keep the selected sensor at the
given temperature
Control direction - when the output should increase with increased value (DIRECT) or should decrease
13

AstroLink 4 micro - astrojolo.com
with increased measured value (REVERSED)
The last tab is Frequency. Here there is only one select box where you can change the frequency of
PWM output. It is usually the best approach to select the highest 31kHz frequency - this frequency is
not audible by humans and also requires low-value LC filtering elements if you want to use it. But
some receivers may not work well with such high frequency, and then it needs to be adjusted down.
14

AstroLink 4 micro - astrojolo.com
Sensors section
Sensors and PWM sections are separate ones, although they work together to provide some combined
functionalities. The sensors section contains four read-only fields that labels may be changed. The
temperature/humidity sensors enclosures are numbered, and the sensor marked with the character “2” will be
displayed in the #2 column in the panel. The sky brightness sensor refresh rate depends on the actual sky
brightness. A darker sky requires a longer integration time. Up to thirty seconds for 21 mag/arcsec2sky, or up to
sixty seconds if darker.
15

AstroLink 4 micro - astrojolo.com
In the Alerts tab you can set temperature change monitor parameters:
Enable temperature alert - here you can enable or disable temperature alerts
Temp. change sensor - it is the sensor that temperature is taken to monitor its value. Make sure the selected
sensor is connected to the device
Temp. change warning - it is the difference between the current temperature and the start temperature that causes
an alert to be triggered. When the temperature difference is close to this value, the temperature window becomes
orange. When the limit is reached, the temperature window becomes red and alerts are emitted (if activated)
also buzz with device buzzer - when the temperature change limit is reached alert signal will be emitted from the
AstroLink device buzzer
also alert with system sound - when the temperature change limit is reached system alert sound will be played
Enable sky temperature warning - when the difference between the sky and the ambient temperature drops below
the specified threshold alert will be triggered. It usually indicates a scenario, when the sky is covered with clouds
Cloud sensor tab contains threshold levels that change the icon representing sky conditions. Default values 8, 12
18 and 25 degrees are usually suitable for the average location. However, if the sensor is used in specific
conditions (desert, mountains, lake, or river proximity) these threshold levels may need to be adjusted.
The third tab called Icons controls the displaying of environmental status icons.
Temperature icon source and Humidity icon source determine if icon color is controlled with values from the first or
second sensor, from the sensor that provides higher or lower value or averages both sensor readings.
Display temperature icon toggles temperature status icon displaying
Display humidity icon toggles humidity icon displaying
Display cloud sensor graphics toggles displaying sky temperature status graphics
The last tab – SQM controls the settings of the optional sky brightness sensor. Numeric fields are used for the
sensor reading calibration. If you want to calibrate the sensor to a reference sky brightness sensor, usually it is
enough just to determine the offset. If after applying the offset there are still significant differences between the
sensors, please contact us, so we can analyze the case and provide a way to determine the Coefficient parameter.
Offset – the difference between the AstroLink sensor reading and reference sensor reading
Coefficient – second parameter that controls sensor calibration
Reset sensor – reset sky brightness sensor parameters to the factory defaults (confirmation window will popup)
Dark calibrate – determines the dark signal of the sensor that will be then applied to sensor readings. The process
requires a sensor cover and no stray or ambient light available. It may take up to three minutes (a confirmation
window will pop up).
16

AstroLink 4 micro - astrojolo.com
12V outputs section
The second section is called the 12V output. Here we have three check-boxes that control DC outputs where you
can connect supply voltage to peripheral devices like mounts, cameras, or filter wheels. Lock outs check-box can
be checked and then the three boxes above will be locked (not clickable). This way you can prevent accidentally
turning on or off any of the connected devices.
Under the cogwheel button settings windows is hidden. There are not many options, however. You can label each
power output, so it can have a meaningful name like 'Mount' or 'CCD main camera'. On the second tab, three
checkboxes control power-on behavior. If the checkbox is checked then the corresponding output will be on after
turning on the power or resetting the device.
17

AstroLink 4 micro - astrojolo.com
AstroLink charts
AstroLink charts are the tool that allows you to monitor the following data that is collected by the AstroLink device:
● temperature, humidity, and dewpoint measured by connected sensors
● sky temperature and the difference between sky and ambient temperature (if the sky temperature sensor is
connected)
● focuser position in steps
● PWM outputs power in %
● switchable DC outputs states
● input voltages value
● total current draw
● total energy consumed
Charts start to collect data at the moment AstroLink panel software connects to the AstroLink device. You can open
the charts window by clicking the corresponding button in the lower-left of the panel. After opening the charts
window the default view is opened - that is a mixed plot of the temperature and focuser positions. The chart scale is
calculated automatically. You can zoom any selected chart range by selecting it with a mouse. Then the scroll bar
will appear, so you can pan the graph. To cancel zoom you need to press a small button on the left side of the scroll
18

AstroLink 4 micro - astrojolo.com
bar. After clicking with the right mouse button in the chart area the context menu will be opened. In this menu
following options are available:
● the first five options can be used to switch between different views of plots that present different data in a
combined way
●Export as image - this option saves the current graph as a PNG image in the folder selected by the user in
the dialog. The saved image will contain exactly what is visible on the chart
●Collect data to file - this checkbox indicates if data is saved to the file. This is checked on by default, and
data files are saved in the My Documents/AstroLink folder. Saved files may be later imported for example
to an Excel sheet and processed
●Data collection period - here you can set the period of the graph. If the newly selected period is shorter
than the already collected data, then data will be truncated. This setting does not affect data collected in
files.
●Data collection sampling rate - you may choose here how often data should be collected. Actual data is
always sampled two times per second. This setting determines how many samples are averaged to create
data points in the chart. Recommended values are 5 or 10 seconds unless you need to have it collected
more often.
●Clear all collected data - clicking here causes all data in the chart to be cleared. It does not affect data
collected in files.
19

AstroLink 4 micro - astrojolo.com
Overcurrent and overvoltage protection
AstroLink panel contain settings to provide overcurrent and overvoltage protection. Both input voltage and total
output current are monitored 200 times per second and measured values are compared to user settings. If any of
these values exceeds settings for some specified time (also configured by the user) then all PWM and DC outputs
will be switched off. Default protection settings are
● voltage: 14.0V. It is also the maximum allowed input voltage for AstroLink device
● current: 10.0A. It is the maximum output current that the AstroLink device can handle safely
● protection sensitivity: 100ms
Overvoltage settings
The value here should be adjusted to the voltage that our power supply provides. If we use a regulated 12V power
supply, then a reasonable value here could be 12.5 or 13V. For 13.6V regulated voltage, we can stay at the default
value of 14V.
Overcurrent settings
This preset should be adjusted to the receivers that we power from AstroLink. If we have a mount that drains 2A
when doing GoTo, a camera that drains 2.5A at maximum cooling power, and a dew cap heater that consumes
1.5A, then the maximum current will be 6A. Plus some current for focuser, and then 7A can be reasonable value for
such configuration. Probably it is the best way to monitor the actual total current drawn in AstroLink panel software
during one session, and then determine the overcurrent value based on this. You can use charts for this and look
for maximum power consumption.
Protection sensitivity setting
When either overcurrent or overvoltage occurs, the device is waiting for this amount of time and checks if this
condition still occurs. If so, then an alert is triggered. However, if overcurrent or overvoltage will end during this
time, no alert will be triggered. Usually, it is the best approach to set a short time, however, it is not always possible.
When the receiver connected to AstroLink (like mount or camera) consumes much power at the moment it is
switched on, then this protection sensitivity time may be increased. But it is recommended to keep this setting low,
like 30 or 50ms.
20