LX200 autoguiding emulator


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To be able to autoguide a mount with LX200 commands, it has to understand the LX200 protocol. If you don't have such a mount (like a Meade LX200, SkySensor2000, AstroPhysics etc.) , you might be able to autoguide using the Iris , PHD Guiding , StarTrack , Astro-Snap , Guide Dog or K3CCDTools or Guider software and a webcam, using the following interface. These software packages give out serial LX200 style commands. Or you could even use it with the self guiding long exposure modified webcam and the Desire Software by Steve Munch .

Click here for connection diagrams for different types of mounts


Connecting cables for SynScan, LX10, LX50, G11 and G8 available now, see price list below

Results from emulator users

The "emulator" consists of a microcontroller (Atmel AT90S2313 or ATiny 2313) together with a MAX232 to shift voltage levels for the RS232 port, and a few transistors and relais to connect to the mount. The microcontroller translates the LX200 serial guide commands into signals for the relais that control the telescope mount.

NEW: USB version available now, it's cheaper because it has less components, click here for pricing

The software for the microcontroller was written by Ronald Gorter. This project may be built for non commercial purposes under GPL-licence. Only the LX200 guide and focus commands are implemented, so a slew or center command does not change the speed at which the scope moves. So this is NOT a complete LX200 telescope drive! Your drive has to be set to guiding speed manually.

There is an option to add four more outputs on pin 16 , 17, 18 & 19 of the processor PB4, PB5, PB6 & PB7. Just add 4 transistors, resistors, relais and diodes as for the other 4 outputs. Those relais will respond to LX200 / Iris focusing commands. This very useful option was requested by Bernard Heathcote.

LX200_Focus_Command (minor command group):

#:F+#   =       Focus in       The 'focus in' command will set PB4 (pin 16 of the processor)

#:F-#   =       Focus out      The 'focus out' command will set PB5 (pin 17)

#:FQ#   =       Quit focus     The 'quit focus' command will reset both pins.

#:FF#   =       Focus fast     The 'focus fast' command will reset PB6 and set PB7 (pin 19).

#:FS#   =       Focus slow     The 'focus slow' command will set PB6 (pin 18) and reset PB7.

An extra PCB layout for a focusing daughterboard is available now. It can be connected to the first board using 6 wires. Or you can use male and female headers to interconnect the boards. Just connect the JP8 header on the main board to the JP11 header of the focus board, and the JP6 header on the main board to the JP10 header on the focus board.

Downloads, you will need some of these files if you want to make your own PCB and program the processor

These PCB's are slightly different from the PCB's available from me! But they will work exactly the same.


Because I get a lot of requests for processors and complete boards, I made the following parts and kits available:
Prices in Euro including sales tax (BTW)

Programmed Processor                                                                    5,=
Main circuit board (empty)                                                            10,=
Main board kit including circuit board and all parts and programmed processor          50,=
Main board assembled and tested                                                        75,=
Focus option circuit board (empty)                                                      5,=
Focus board kit including circuit board and all parts                                  20,=
Focus board assembled and tested                                                       30,=
USB version board kit including all parts and programmed processor                     50,=
USB version assembled and tested                                                       75,= 
USB version assembled and tested and built in a box                                    85,= 
USB version assembled and tested and built in a box  + guider cable (see below)        93,=
Cable for connecting to SynScan, LX10, LX50, G11, G8  (RJ12 6way)                       8,= 
USB Opto Isolated Bulb cable for Canon 300D and Canon 350D
Including 2.5m cable with 2.5mm jack plug                                              35,=
USB Opto Isolated Bulb cable for Canon 300D and Canon 350D
Including 5m cable with 2.5mm jack plug                                                40,=
Shipping to Europe                                                                      6,=
Shipping outside Europe                                                                10,=
Aditional charge for PayPal payments                                                 3.5% of total amount
Payment from Europe via Bank                                                       No extra costs

Interface schematics in PDF format

Serial LX200 Interface + Focus board component list and placement in PDF format

USB driver for XP    All available USB Drivers

USB LX200 Interface component list and placement in PDF format

From now on you can pay by PayPal. (August 5th 2005) For more information please e-mail me: Albert van Duin

Description: New USB interface


Description: New USB boxed


Description: pcb


Description: pcb


Description: parts


Description: completed board



NEW: USB Opto isolated Bulb cable for Canon 300D and 350D available now, will appear as an extra COM port, click here for pricing

Description: E:\Users\Albert\My Documents\USB-opto-bulb.jpg


Description: E:\Users\Albert\My Documents\USB-opto-bulb2.jpg



What if the interface doesn't respond?

Make sure the interface is powered up and connected to the correct COM port. If possible measure the output of the 7805 regulator, it should be 5V.

Make the appropriate settings in the autoguider software to set the correct COM port and protocol. (LX200)

Make sure no other program using the same COM port is active. Thanks to Bruce MacLeod I got information about Pocket PC software blocking the use of Iris and the emulator because this software took complete control of the COM port. Some software for communicating with Palm Pilots does exactly the same.
It may be software you are not even aware of because it is started up at boot time!

Testing / Troubleshooting the LX200 emulator interface

How to connect the interface to your mount


Revision History:

18 October 2001: First release of the software.
27 October 2001: Board was tested and PCB artwork was uploaded
29 October 2001: New source code and HEX file that uses the Iris Remote Focus commands
30 October 2001: New source code and HEX file for slow and fast focusing and new PCB layout
31 October 2001: New source code and HEX file bugfix init of port bits, only needed if you use the focus mode
14 December 2001: Link to another AVR programmer was added
21 October 2002: Kits and programmed processor available
15 January 2003: How to connect to a Syntha HEQ5 / EQ6 handpad
16 January 2003: How to connect to a Celestron Celestar handpad
18 January 2003: Changed some pictures showing connections
19 January 2003: Added to the FAQ and added MTS3 connections
17 February 2003: Added pictures of new production PCB
29 April 2003: Added LX50 connections
5 May 2003: Added new schematic for commercial PCB and Ultima connections
4 June 2003: Added Losmandy G8 / G11 connections
21 July 2003: Added GP connections
3 December 2003: Corrected an error in the text about the focus board (Thanks Mark!)
31 December 2003: Added link to Guide Dog software
4 March 2004: Added schematic for focuser
13 April 2004: Extra schematic for focuser
4 August 2004: added some links
6 September 2004: added connections for Mel Bartels Scope Drive
4 December 2004: bugfix for hexcode concerning a focusing speed error issue found by Heiko Wilkens
This bug is no problem if you are using only a single speed focuser, the FAST and SLOW commands are reversed.
25 April 2005: Added LX10 connections
24 July 2005: Added SkyWatcher SynScan connections
5 August 2005: Pay Pal can be used now!
6 August 2005: Added Testing/Troubleshooting page to FAQ
3 December 2005: added more pictures of the Vixen DD-1 connections
11 December 2005: USB interface available soon!
29 December 2005: Results from Gordon Train added
7 January 2006: Added picture of USB Prototype
14 January 2006: Added LX5 connections
24 January 2006: Added pricing and pictures for USB version
31 January 2006: Added USB drivers
9 February 2006: Added User Results page + Components list serial LX200 interface
15 Februari 2006: New sub-page with all Do It Yourself files
23 Februari 2006: Changed layout, made "How to connect page"
25 May 2006: Added cables for connecting to different mounts
21 June 2006: Added LX6 and DynoStar connections
8 July 2006: No service available until August 1st 2006, sorry for the inconvenience!
6 August 2006: Service available again!
27 January 2007: Link to PHD Guiding
27 February 2007: New USB interface 25 March 2007: New USB interface assembly instructions + drivers
15 April 2007: Added Canon 300D/350D Opto Isolated USB Bulb cable for use with ImagesPlus and DSLRFocus
4 November 2007: Added boxed version of LX200 emulator interface
5 April 2008: changed pictures of connections to be compatible with the USB PCB

Last update of this page: Saturday, April 05, 2008


Use of the information on this page is at your own risk. If you don't know about electronics, please ask someone who does know to help you. Don't blame us for smoke signals!

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