11 replies to this topic

[CharlesC]

Below are details on how to add bluetooth control to your LN300 video camera.  If you have a Micro Ex or DSO-1 (both based on this camera) this mod will not work because those cameras have an added RS485 chip. (you could make it work by skipping PART 1, and adding a RS485 tranceiver chip to bluetooth box, but will leave that to someone else to figure out) This mod taps a 3.3V level TTL TX input pin from the RJ11 DSP and connects it too an external $6 bluetooth module.  Using standard SSP bluetooth drivers on your PC and Mallincam Micro Ex control program (or other similar programs) you can connect wirelessly to your LN300 as a com port and access LN300 menus on your PC.

 

This mod is an extension of cc_hello's thread "Adding PC control to LN300" which was extremely helpful in creating this bluetooth mod. Here is the original cc_hello thread.  http://www.cloudynig...00#entry6098886

 

This mod involves two parts. First, the four pin Iris connector on the LN300 must be wired with; 12V, GND, TTL TX, ADkey.  Second, an external bluetooth box must be made to connect to the LN300 Iris connector.

 

PART 1:

The Iris connector is not used in the LN300, but there is a four pin cable to it running from back board to front board. We will use this cable to bring out 12V, GND, TTL TX, ADkey signals.  Locate the four pin cable and cut it from the front board leaving 1/2" of wire (in case you want to restore it in the future).  Copying ccs_hello mod, use third pin to access 3.3V TTL TX input signal on front board.  Solder in a 2400 ohm resistor and connect that to the yellow wire of the four pin connector.

 

 

Get the remaining three signals (12V, GND, ADkey) from the back board.  Connect the red wire to 12V and black wire to GND on the power connector.  Connect the white wire to PCB as show in photo.

 

You are now finished with Part 1, and you can now reassemble the LN300.  When you power up the LN300, use a volt meter to verify 12V and GND are in right place on the Iris connector.

Locate lower-left pin on Iris connector  and that is 12V. 

Locate lower-right pin on Iris connector and that should be GND.

Locate upper-left pin on Iris connector and that is ADkey (won't use it in this mod, but you could later)

Locate upper-right pin on Iris connector and that is 3.3V TTL TX input signal we will use shortly.

 

 

PART 2:

 

Next we need to construct a bluetooth box with cable to an Iris connector.  Ebay is your friend to find parts cheap, but it takes a while to get them from china.  Buy a HC-05 bluetooth module on ebay for about $6 shipped. Buy a L78L33ACZ 3.3V voltage regulator for about $1 that will power the HC-05. Buy a .1uf cap that goes on 3.3V to GND on regulator.  Buy a .33uf cap that goes on 12V to GND on regulator.  Buy a small plastic box and cable restraint to contain it all.  The HC-05 has a connector with VCC,GND, and TX output marked.  Connect VCC to 3.3V regulator output.  Connect three cable wires; 12V to 3.3V regulator input, GND to regulator and HC-05, and TX wire to TX signal on HC-05.  Button it up and you are done.

 

The Bluetooth module has a button and LED that need to be accessed to do initial link to PC.  The sequence is like most bluetooth devices so I'll omit that for now.  Really should break out the button and LED on the HC-05 to box exterior, but haven't done that yet.

 

Now you are ready to plug it all in and see if it works.   Link the bluetooth to your PC and you will see two com ports become active.  Only one works.  Manually set the LN300 System Menu with ID=1 and 9600 baud.  Run Mallincam Micro EX control program and select com port and connect.  The PC program's buttons should now activate LN300 menus.

 

I put a short pigtail on my box and velcro'd it to the top of my telescope.  Seems to work well and will give it a good test soon.  This mod description is rough, but should give someone with some experience building gizmos enough info to make it happen.

Edited by Charles Copeland, 11 September 2014 - 08:18 AM.

[ccs_hello]

Charles,

 

Great job!

This could be an interesting project.

I assume if the other side is a PC, you can use some of the popular videocam control programs to do "button pushes" (actually mouse clicks).

 

On the other hand, I guess someone can write the Android or IOS app to do the same.

 

Actually, it may be very cool that the analog video output on the videocam side can be decoded into images then send over via WiFi to the same Android or IOS device to be displayed.

This concept would be similar with using a WiFi tablet to watch over a home remote IP-camera.

 

Clear Skies!

 

ccs_hello

Edited by ccs_hello, 10 September 2014 - 11:01 PM.

[CharlesC]

ccs_hello,

 

Thanks! The other programs should work as its just another virtual com port.

The Mallincam program doesn't handle exceptions such as turning off LN300 without disconnecting.

When that happens you have to use Device Manager to kill it cause program locks up.

Same when you select the wrong com port. Might make my own that also lets you use keyboard.

 

Actually I'm tinkering with Android app right now to connect to LN300 via bluetooth. 

Would be handy to use Android phone to control LN300 when I don't have laptop with me and just using display.

Probably ought to just make an ADkey wired remote, but that would take the fun out of it!

 

The video part is over my head, but the missing link.  SkySafari can control scope wirelessly with Android,

but would be cool if it could get video too.  Would be good project for someone with wireless background.

 

I'm thinking of making another bluetooth box for telescope control and slapping it on OTA too.

Amazon sells $40 52gig "video senders" with transmitter and receiver.

If I do all that, I can set my telescope on the porch with a battery pack, and be completely wireless.

Could work telescope all night long in the winter while sitting inside where its warm.

 

Charles

[telfish]

There is  quite a lot of space within a LN300. Is it possible to just incorporate the module within the ln300 case and avoid the extra box?

 

Great project my order for a BT module is on it's way.

 

 

Terry

[ccs_hello]

Terry,
Spacewise, it is possible.
On the other hand, Bluetooth and WiFi are RF
emitter which (1) will be shielded by metal chassis and
(2) inject noise to camera board. Not recommended.
Clear Skies!
ccs_hello

[telfish]

Terry,
Spacewise, it is possible.
On the other hand, Bluetooth and WiFi are RF
emitter which (1) will be shielded by metal chassis and
(2) inject noise to camera board. Not recommended.
Clear Skies!
ccs_hello

 

 

Thanks CCS.

 

My LN300 has a plastic box and just a PCB at each end. I appreciate the interference thing though.

 

 

Terry

[mngs]

Hello Charles,

 

It should be very useful also comportable.

I will make it based on your instruction. let me post it with pictures soon.

I have one question about value of register.

am i have to use exact value, 2400ohm on the board?

I can't find the exact number of register in my office. Could you please advice?

 

Thanks,

Gisik Nam

[Relativist]

Terry,
Spacewise, it is possible.
On the other hand, Bluetooth and WiFi are RF
emitter which (1) will be shielded by metal chassis and
(2) inject noise to camera board. Not recommended.
Clear Skies!
ccs_hello

If such noise is found to be an issue (with low energy Bluetooth it's less likely than wifi) then the two modifications if suggest are 1) optoisolation between board and transmitter and 2) using separate power for the Bluetooth (maybe a 9V battery).

[CharlesC]

Hello Charles,

 

It should be very useful also comportable.

I will make it based on your instruction. let me post it with pictures soon.

I have one question about value of register.

am i have to use exact value, 2400ohm on the board?

I can't find the exact number of register in my office. Could you please advice?

 

Thanks,

Gisik Nam

 

I believe ccs_hello original circuit used this resistor to level shift from 5v to 3.3v.  However, since the HC-05 board is already 3.3V levels, I don't think its required.  I don't have schematics or detailed data on RJ11 TX pin, so to be on the safe side, I left 2400 ohm resistor in place mainly to limit current  in case of  static discharge on Iris cable that could damage RJ11.  I checked with oscope and signal drop across resistor is only 100mv, so TTL level is not affected by resistor. Adding two reversed biased diodes between 3.3V and GND tied to TX pcb signal would be highest level of protect from static discharge, if you are overly concerned about static discharge.

 

The value of the resistor is not critical. Find a resistor from 1000 to 3300 ohms and it will give you some protection against static shock. 

[CharlesC]

 

Terry,
Spacewise, it is possible.
On the other hand, Bluetooth and WiFi are RF
emitter which (1) will be shielded by metal chassis and
(2) inject noise to camera board. Not recommended.
Clear Skies!
ccs_hello

If such noise is found to be an issue (with low energy Bluetooth it's less likely than wifi) then the two modifications if suggest are 1) optoisolation between board and transmitter and 2) using separate power for the Bluetooth (maybe a 9V battery).

 

 

RF getting into LN300 is not very likely with a 12" or greater length Iris cable.  Bluetooth only pulls 30ma so is relatively weak RF level.  If Bluetooth board was inside the LN300 case  RF would certainly get into the very sensitive video amplifiers.  It is possible the Bluetooth module could induce RF back into the power cable, but by pulling 12V/GND right off the power connector should limit that possibility.  If it were a factor a toroid inductor (the size and shape of a lifesaver candy) wrapped around 12V wire inside Bluetooth box would cure it.   I've now test this mod for two nights of observing and have not experienced any problems with RF getting into LN300, so it probably is fine. 

[ccs_hello]

In my design, I put a 3.3K resistor on each end of the remote control wire for protection of stray spikes (everyone's situation differs...)

 

I'd rather spent 2 pennies on resistors as opposed to a $60 cam or a $600 laptop (a good insurance.)

 

 

BTW, the original BT question was to put it inside the videocam thus my answer.

 

Clear Skies!

 

ccs_hello

[CharlesC]

Just wrote Android App to control LN300 with bluetooth using above mod.  See link for details.

http://www.cloudynig...o-ex-dso-1-too/

Edited by Charles Copeland, 19 September 2014 - 05:57 PM.