EOSbox

[yesyes]

During the last few days I built myself a little box that contains a USB hub, a serial to USB converter and the serial to shutter release circuit all in one.

The purpose is to have only a single USB cable go to my EOS 1000D camera instead of USB and serial. The box screws to the bottom of the EOS using the 1/4" BSW tripod thread. One side has mini USB socket just like the one on the EOS as the USB in. So I can use the same cable that I would normally plug in the camera. The other side has 2 short cables coming out; one mini USB cable and one shutter release cable. Both plug into the side of the camera. As an added bonus there is a spare USB port that could be used for a guide cam for example.

Staring point: One Hannah Montana 4 port USB hub. That was the cheapest (£1.24 on ebay) USB hub I could find that has a mini USB input and seemed to have enough space left inside (after removing the Hannah Montana insert) for additional circuitry.

I opened it up and unsoldered 3 of the 4 USB sockets to make some room and reduce the weight. Then soldered a short bit of cable with a mini USB plug at the end to where one of the USB sockets was:

Next I built the serial to shutter release circuit as small as possible

The serial to USB converter was salvaged from a serial to USB cable by cutting open the plug that contains the circuit board. I then soldered it to another USB port on the USB hub circuit board:

Then I squeezed everything back into the USB hub enclosure:

A big hole in the enclosure (where one of the USB ports was) allows me to put a screw through so that the whole box can be attached to the bottom of the camera (the screw was salvaged from an old, broken office chair)

Here is what it looks like when attached to the camera:

This is the box with its components labelled:

Attached is a PDF file with the schematic of the box (it does say 2 port USB hub but I ended up using a 4 port).

EOSbox (Schematic).pdf

[JKB]

Excellent, just what I need for my 30d

Where did you get the USB-Serial convertor?

Cheers

[Psychobilly]

Superb thats a really neat solution

Billy..

[MG1]

Nice one Chris, that's a great solution. Was thinking something similar myself in order to get my filterwheel guide cam and cam all onto one cable too.

Very neat job.

[yesyes]

Thanks for the comments

Where did you get the USB-Serial convertor?

I bought a serial to USB converter cable and carefully cut open the serial plug that contains the converter circuit.

I did a bit of research before. Most of the cheap ones don't have the hardware handshake lines (RTS, DTR, ...) but only the serial send (TxD) and receive (RxD) lines. The serial shutter cable uses the RTS line, so you would need a converter that supports that. I found that the Prolific PL2303 chip supports it, so I bought a converter based on that chip. The FTDI chips also support that but are usually a bit more expensive. Another criteria for selecting the converter was driver support. Prolific have drivers for the PL2303 for all Windows versions, including Win7 x64.

[step_hen]

Neat- thats a great piece of work. what was the total cost to put together?

Stephen

[beamish]

That's ideal and very neat ! Need to start marketing it

[yesyes]

what was the total cost to put together?

£1.24 - USB hub

£2.54 - USB to serial converter

£0.75 - 2.5mm stereo plug

£0.19 - 4N25 opto isolator chip (bought as a 20-pack for £3.70)

£1.00 - estimated cost of other bits and pieces that I already had (screws, nuts, washers, bit of strip board, diode, resistor, cable clip)

=====

£5.72 in materials

plus several hours of fiddly work ;-))

[astrovirus]

Very nice, and indeed save a lot of cable mess.

But I was just wondering why you need for the 1000D (and other DIGIC III and later models) as they are controled by the USB alone. This would be handy for my 350D though, saves me some cables, altough my peltier cooling has resulted in an increase in cable mess coming from the camera.

Regards Tim

[yesyes]

That's ideal and very neat ! Need to start marketing it

I was thinking about that. But I don't think that would be viable once I factor labour time into the price. I didn't count but I'd estimate about 10-12 hours of work.

Plus cost of things that break. I broke one USB hub, probably while unsoldering the USB sockets. The PC would see the camera when I switched it on and bring up the "do you want to download the images" dialog but then disconnected before it even gave me a list of the images... Luckily I ordered 2 hubs....

It would be sooo much easier and less risky if there was a USB hub chip available to hobbyists.. ;-)

[yesyes]

But I was just wondering why you need for the 1000D (and other DIGIC III and later models) as they are controled by the USB alone.

Unfortunately mirror lock-up can't be controlled via USB with Digic III cameras. Only Digic 4 support that. You can simulate mirror lock-up using LiveView (that's what APT does without a shutter cable) but that causes amp glow.

[Viv]

That's a nice bit of work (want to do another one) ;-)

Am quite concerned on the Hannah Montanna though !

lol

[yesyes]

Am quite concerned on the Hannah Montanna though !

lol

You can have the inserts with the picture if you want ..

[Psychobilly]

T

Am quite concerned on the Hannah Montanna though !

lol

but look on the bright side it drives the price down

[Spikey]

Nice work, very neat.

[Photosbykev]

very compact unit, ideal for the digic II/III bodies. Maybe Astronomiser should be asking you for marketing rights

[nightvision]

Very neat! How did you identify which USB-Serial cable to buy or did you just happen to have one with the correct chip in it? I notice that some cables on ebay say 'supports full RS232 spec', cheap enough to try.

[nightvision]

Found one with the 2303 chip set:

USB to Serial RS232 DB9 Adapter Converter Cable Lead PC | eBay UK

[astroimpulse]

That is really REALLY good!

A neat solution that I might try as it would solve the two cable thing.

Have you tried it out yet? If it works sweet I'll give it a go.

More yesyes inspiration *thumbs up*

Do I need the 4N25if I have an opto-isolater usb to serial converter? If I can bypass that little bit it would be easier still.

[yesyes]

Very neat! How did you identify which USB-Serial cable to buy or did you just happen to have one with the correct chip in it? I notice that some cables on ebay say 'supports full RS232 spec', cheap enough to try.

I did check all sorts of USB-to-Serial cables on ebay to see which offers list the chip used in the cable. Then I downloaded the datasheet for the chip and checked whether it supports RTS. I only considered buying a cable where I knew what chip was used and that it supports RTS.

I found that the Prolific PL2303 and the FTDI FT232 series both work for this.

There might be other cables/chips that support RTS and the other handshake lines but most offers on ebay and elsewhere did not list the chip used in the cable, unfortunately.

[yesyes]

That is really REALLY good!

A neat solution that I might try as it would solve the two cable thing.

Have you tried it out yet? If it works sweet I'll give it a go.

More yesyes inspiration *thumbs up*

Do I need the 4N25if I have an opto-isolater usb to serial converter? If I can bypass that little bit it would be easier still.

I have tried it in a dry run but not yet in a imaging session. There seems to be a small problem in that the camera starts taking exposures when the shutter cable is already plugged in when you power up the camera. It works fine when you power up the camera first, then start APT and then plug in the shutter cable.

It looks like the solution is to invert the signal coming from the serial port. But I think I can live with that little limitation and there is not enough room left in that box for an inverter chip.

I'll wait till I can test it out in an actual imaging session and then decide whether I need to modify it or not.

Regarding the opto isolator...

There are other ways to do this without the isolator. You can use a transistor instead. I got the schematics for the shutter release from here:

Cable Release and Serial Port Cable for the EOS Digital Rebel

This shows schematics for both versions, the one with the transistor and the one with the opto isolator.

I didn't want to risk damaging the camera (it took a long time to convince HER that I need to spend a lot of money on a DSLR) so I opted for the opto isolator version.