AstroEQ Tutorials Wiki


Frequently Asked Questions

Making Connections

AstroEQ comes with either 4 or 5 different connections which are as follows:

  • '12V DC'
    • This is the power connector, a 5.5×2.5mm Jack (Centre Positive).
  • 'To PC'
    • This is a mini-USB port which you connect to a PC
  • 'RA Motor'
    • This connects to the Right Ascension Stepper Motor via an RJ11 Cable.
  • 'DEC Motor'
    • As above, except this is for the Declination Motor
  • 'ST4 Input'
    • An optional ST4 port for guiding.

When making the connections, always ensure to connect the motors up first. Never unplug or plug in a motor cable while AstroEQ is powered as this may damage the motor driver circuitry. Once the motors connected, then plug in the 12V DC power supply. Finally plug in the USB cable to the computer. You can plug the USB cable in before power, however this can in certain cases cause AstroEQ to not respond to the computer.

When wiring up the motors, the connectors are 6-way RJ11 style cables. You should use the following pinout:

  1 2 3 4 5 6
  x A B B A x

Where 'x' is no-connect, 'A' is one of the motor coils, and 'B' is the other motor coil. It doesn't matter which coil is A and which is B. Nor does it matter which side of each coil is which. You should however use the same pinout for both motors to make setup easier.


Blinky Lights

You will notice that on the left hand side of the AstroEQ case there are 3 lights. These are labelled as follows:

  • 'Power'
    • This indicates that AstroEQ is connected to a power supply.
    • If the light is off, make sure the power supply is connected and the correct polarity
  • 'Link'
    • This indicates that the status of the USB port
    • If it is blinking quickly, the USB port is connected.
    • If it is blinking slowly, the USB port is not connected.
    • If it is solid then the connection failed.
  • 'Status'
    • This indicates communication with EQMOD
    • A short blink will be seen each time EQMOD sends a message to the controller.
    • When power is first connected or during programming, the light will blink 3 times.

These lights are useful for making sure that AstroEQ is working correctly. If they do not behave as described, try unplugging power/USB for 15 seconds or so and reconnect.


What Values

AstroEQ is designed to be a universal Goto controller. What this means is that to make AstroEQ work with your mount it must be told about the gear ratios of each axis of your mount. There are three key values for each axis which must be known:

  • 'Step Angle'
    • A stepper motor turns a set amount with each 'step'. This amount is expressed either in 'Steps per Revolution' or 'Step Angle'.
    • AstroEQ needs to know how many degrees the motor turns with each step.
  • 'Motor Gear Ratio'
    • This is the ratio of any gearing between the output shaft of the motor and the worm on the mount
    • For example if you have a 40Tooth gear on the worm and a 10Tooth gear on the motor, the gear ratio would be 40:10 = 4:1
  • 'Worm Gear Ratio'
    • Your mount will have a built in worm gear which has an associated gear ratio. These values are usually well known.
    • This is needed for EQMOD to be able to perform Periodic Error Correction (PEC)

Along with these three bits of information, there are some other bits of information that AstroEQ needs to know. These are as follows:

  • 'Goto Speed'
    • This is speed at which goto movements will be performed.
    • It is measured in multiples of the Sidereal Rate (e.g. 2 = 2x sidereal)
    • Not all speeds are possible, so the Configuration Utility will round the value down to the nearest available.
  • 'Driver Type'
    • This is the type of IC used for driving the motors.
    • For ALL AstroEQ controllers purchased, set this to: DRV8824/5
  • '1/16th Microstepping'
    • For low gear ratios, this can be used to increase accuracy.
    • Any 'Motor Ratio' less than approximately 50 should have this set to Enabled. Otherwise set this to Disabled.

If you are unsure of your gear ratios, a list of common settings can be found here.


Motors Not Moving

You have successfully set up your AstroEQ controller, programmed it with the Configuration Utility and entered the correct gear ratios. So now you have moved on to testing. You have installed EQMOD and loaded it up to connect to the mount to start moving the motors, you push the NESW buttons but nothing seems to happen, what next?

There are a few things that might be happening:

  • 'You hear nothing and nothing happens'
    • Make sure that the connections to the motors are all correct and that the cables are properly seated.
    • Ensure that your power supply is rated for at least 2A so that there is enough current available for the motors.
  • 'You hear a slight rumble but nothing happens'
    • First thing, are you pressing and holding the NESW buttons - clicking will only make the motors move for a fraction of a second. Press and hold. Do the motors start moving now?
    • Is the current limit set correctly? See the tutorial here.
    • Make sure the motor cables are properly seated, a loose connection can cause issues
  • 'The motors move, but erratically'
    • Make sure your scope is balanced if attached and that both axes are free running - the motor might be stalling if there is too much imbalance.
    • Again check cables and the current limit.
    • You may be trying to make the motors move faster than they are capable of - the dual-axis kit motors for example can only move at speeds < 50x the sidereal rate.

If none of these help, feel free to get in touch, or alternatively there is a long thread here which has lots of information in it (I'm slowly merging it into this FAQ).


Arduino Mega EEPROM Read Failed

When trying to set up an Arduino Mega 2560 board, and after uploading the firmware successfully, the configuration utility reports EEPROM Read Failed.

This is an issue with the bootloader that is used on many Arduino Mega boards and clones. The bootloader has a mistake in it which fails to reset the watchdog timer. The AstroEQ firmware uses the watchdog as part of the EEPROM configuration process causing the bootloader to enter an infinite reset loop.

The issue with the bootloader was solved many years ago in 2013. Even though the bootloader was fixed in 2013, many of the new production boards and clones use the old bootloader, so even if you bought it after 2013 it will likely need updating.

If you have another Arduino to hand or other AVR programmer, I would highly advise anyone with an Arduino Mega 2560 version (doesn't affect the Mega 1280 or AstroEQ boards) to flash the new bootloader.

Updating Bootloader

The latest version of the bootloader is already included in the Arduino IDE version 1.6.7 or newer. You can simply use the “Burn Bootloader” option in the Arduino IDE. This will require an AVR programmer.

If you don't have an AVR programmer, but do have another Arduino board to hand, you can use the ArduinoISP technique. Instructions can be found on the Arduino Webiste here.