External bluetooth controller for the Synscan hand controller.
Allows remote connection via the handset serial port to read the position of the scope and to slew it to objects in programs like Stellarium.
Only 3 modules inside all available from Gearbest/ebay, no programming (except if you need to reprogram the name and baud rate of the BT module). One spare ST4 cable required as it has the full six wires for powering the modules from the handset and will require one end to be cut off.
Total project cost under 10 UKP which is way cheaper than the commercial versions.
HC-05 Bluetooth module https://www.gearbest.com/other-accessories/pp_227678.html?wid=83
Power convertor module http://www.gearbest.com/development-boards/pp_51010.html?wid=21
RS232 to TTL convertor https://www.ebay.co.uk/itm/2Pcs-Com-Serial-Board-Max232cse-Transfer-Rs232-To-Ttl-Converter-Module-Ic-New-U/132187217126?hash=item1ec6f8dce6:g:GJMAAOSwKOJYIEc4
If the pins on the RS232 module are identified different from the diagram the Tx & Rx pins at TTL levels go to the bluetooth module and the Tx & Rx pins at RS232 levels go to the Synscan.
There are other RS232 convertor module available which are smaller, I only used this as it was the only one I had. I didn't use the RS232 connector on it because the serial cable that comes with the sysncan has no DC power available. Using an ST4 cable means 12V is available for the modules in the bluetooth controller, you will need to cut off one end of the cable and pull back the insulation and connect the following wires as detailed in the included diagram at the pin connections.
PIN 1 - White is +12V
PIN 2 - BLACK is the RS232 Receive line
PIN 3 - RED not used so cut it back
PIN 4 - GREEN is GROUND.
PIN 5 - YELLOW is the RS232 Transmit line
PIN 6 - BLUE is not used so cut it back
WARNING: I accept no liability for any damaged caused by incorrect data, wiring, setup, voltage settings. This project is entirely at your own risk.
DEFINITELY MAKE SURE to set the power convertor to 3.3V output BEFORE connecting to anything else.
Instructions for setting up the name and UART settings for a HC-05 can be found online, UART defaults should be 9600,n,8,1 which will work on the Synscan so this step is only required if the UART settings are not as above or you just want to change the bluetooth device name to something like "Synscan".
Once paired and connected with the host PC Bluetooth the Synscan comms port will be available to set up a new telescope connection in Stellarium. You don't have to go to PC Direct mode on the Synscan for a connection with Stellarium however if you do go into PC direct mode it may also be possible to use ASCOM & EQMod but I never had much success with it (the synscan PC direct interface is not the best and kept dropping the connection).