Installation

indi_celestron_aux is not included with indi-full by default. It is a new separate driver and at the moment must be installed from source. You can install current version of the driver from the Nightly INDI PPA. for Ubuntu 16.04 or newer. It will probably migrate int main PPA at next release. This driver is a full replacement for the NexStar Evolution driver which will be discontinued in the near future.

Warning: This is a new, beta-quality driver and should be treated as such. There are no known functional issues with it and only one long-runtime-stability issue. Nevertheless, the driver should not be left operational unattended.

Requirements

For building the driver you need standard development environment (gcc, cmake, libraries) plus indi library dependencies. For building Debian/Ubuntu packages you need additionally build-essential, fakeroot and dpkg-dev packages installed.

Compilation

The building from source procedure is simple. You need to have standard indi development environment installed. Usually it is a package with a name like libindi-dev or similar. You also need gcc and standard development libraries. Assuming you have the indi-3rdparty source tree in Projects/indi-3rdparty directory, run the following:

mkdir -p ~/Projects/build/indi-caux
cd ~/Projects/build/indi-caux
cmake -DCMAKE_INSTALL_PREFIX=/usr/local -DCMAKE_BUILD_TYPE=Debug ~/Projects/indi-3rdparty/indi-celestronaux
make -j4

If you have Debian/Ubuntu based system you can build debian package for the driver by running the following code (having indi-3rdparty tree in the same place and debian development packages installed):

mkdir -p ~/Projects/build/deb-indi-caux
cd ~/Projects/build/deb-indi-caux
cp -r ~/Projects/indi-3rdparty/indi-celestronaux .
cp -r ~/Projects/indi-3rdparty/debian//indi-celestronaux debian
cp -r ~/Projects/indi-3rdparty/cmake_modules indi-celestronaux/
fakeroot debian/rules binary

The packages will be build above the driver directory (in this case in ~/Projects/build/).

Features

The Celestron AUX driver provides GOTO and sky alignment functions of Celestron mounts which support AUX protocol and is designed to work over all available communication channels. It is modelled after EQMod driver for skywatcher mounts. It works directly with mount and axis controllers, without any help from the Hand Controller. In fact the HC may interfere with the driver operation and is better left disconnected from the mount or not used. The only potential function left to the HC is working as a serial interfece to the mount. In principle, it should support any Celestron mount using AUX command set (most of them) with SkyFi wireless module, additional or build-in or over any type of serial connection (PC/AUX port with proper level converter or Hand Controller serial port). The driver was tested with NexStar Evolution (Alt/Az) and CPC (EQ) mounts.

Operation

The driver operation should be similar to other mount drivers. You need to set communication mode (Serial/TCP) in communication setup. The driver requires alignment (by sync operation after pointing to the selected object). Even one sync point is enough to have it operational in AltAz mode if the mount was properly levelled. The EQ mode usually requires more sync points. For completely misaligned mount you need at least 3 sync points to have accurate pointing. 

Connectivity

USB/Serial

Celestron AUX driver can use any type of serial connection between the three offered by Celestron scopes (i.e. CPC series). The serial connections are listed below with their main characteristics.

1. HC: serial cable connected to hand controller serial port.
   • 4 pins connector (RJ11).
   • 3 wires used: GND, TX, RX.
   • RS-232 serial voltage levels (+5V,-5V).
   • 9600 baud transmission speed.
   • No transmission flow handshake, no echo.
   • Command protocol: pass through (mostly AUX protocol encapsulated inside HC messages).
2. AUX: serial cable connected to Celestron AUX port.
   • 6 pins connector (RJ12)
   • 5 wires used: GND, TX, RX, CTS, RTS
   • TTL serial voltage levels (+5V, 0V)
   • 19200 baud transmission speed
   • Half duplex CTS/RTS handshake with echo
   • Command protocol: AUX
3. PC: serial cable connected to Celestron PC port
   • 8 pins connector (RJ45)
   • 5 wires used: GND, TX, RX, CTS, RTS
   • RS-232 serial voltage levels (+5V,-5V)
   • 19200 baud transmission speed
   • Half duplex CTS/RTS handshake with echo
   • Command protocol: AUX

Celestron AUX driver autodetects the type of serial connection, setting proper transmission speed, proper serial line handshake and proper command protocol. Serial connections details are just shown as an aid for Celestron scope to computer cabling.

As modern computers generally no longer have serial interfaces, a convenient way to make a serial connection to a Celestron scope is to use an USB to serial converter with the proper cable as mentioned in the previous list.

Beware of cheapest USB/serial converters, they have serial lines with TTL levels (+5V,0V). So, they work with AUX port only. Connections to HC and PC ports require a true USB/RS-232 serial converter with symmetric voltage levels (+5V,-5V).

On the other hand old standard RS-232 is symmetric +/-12V signalling should NEVER be connected to the AUX port. Nothing should be connected there without proper level converter. The AUX port is non-standard and connected directly to the bus between all motor controllers and main board. There is an oportunity to burn all scope electronics by connecting wrong signals there.

Network connection

This type of connection can be used with scopes with WiFi interface like NexStar Evolution or any other Celestron scope equipped with SkyFi Wi-Fi adapter. Except for selecting the TCP connection mode and filling in proper IP address/Port (out of the box it is IP:1.2.3.4, Port:2000). It is well advised to change this default values since they are actually incorrect. The 1.2.3.4 is an actual public IP address assigned to some network in Moscow, Russia (of all places ;) and should never be used for embedded systems in local networks. It is best to switch the scope to AP mode and connect it to your local network or dedicated access point. The rest of the communication functions exactly like over PC/AUX connection, since SkyFi is just a serial-over-ip adapter.

First time connection

INDI Celestron AUX connection tab.

To select serial connection simply press "Serial" button of "Connection Mode" property in Connection tab and set the USB port where Celestron scope is connected to. Baud rate is set automatically by driver. Displayed baud rate may differ from real interface speed.

Linux USB

If the controlling system, i.e. a raspberry pi, runs a linux operating system, when more than one USB device are connected, the persistence of USB port number for the same physical USB port is not guaranteed after a system reboot. This problem has two solutions:

1. Enable USB port scan in communication tab page.
2. Bind USB device under a static name.

Usage of USB port scan is straightforward, you just need to enable it in the Celestron AUX Connection tab. Sometimes, if you have several devices connected to USB, USB scan can fail or can mess up your devices.

The alternative solution of USB static name always works, but it is a little more tricky to set up. Several examples can be found searching over internet for "how to bind USB device under a static name".

Issues

There are no known basic functional bugs in this driver, but there are multiple missing features and it is still not as stable as it should. If you found a bug, please report it in (preferably) github issue tracker for the driver or a main INDI project issue tracker. (You can log in with a variety of existing accounts, including Google, Yahoo and OpenID.)