Webcam Mod wiring

[malc-c]

Guys,

I have been reading up on various web sites on doing the long exposure and amp on/off modifications to a SPC900 webcam. From what I can see, the control of these mods are done by making a pin on the parallel port change state. Can anyone confirm this ?

Also, I gather most of you guys use K3CCDtools for controlling these settings. Does this (or other applications) have the ability to choose USB as an option, or do the parallel / serial converter come up as additional com ports (like COM 16) on the PC.

[leenewtoastro]

to answer 1 of those malc. a usb serial adapters does appear as a com port on your pc

[malc-c]

Lee, that's true, but most of the adapter (serial to USB at least) get listed as a comm port under device manager, so guess that would work. I was curious as to whether or not the software used to control modded cameras would work with a direct USB connection, typically a HID descriptor.

[leenewtoastro]

isnt it a case of imaging is still handled by the usb side while exposure times or whatever lx does is handled by the serial port?

and thats why a member was confused why his modded cam didn't work as the guy who modded it for him did not reattach the usb cable so the guy thought you only needed 1 cable from cam to pc but thats not the case. its usb and serial to the 1 cam.

is how i understand it?

[malc-c]

Yes, that's correct. The control of the shutter is done via a connection to the LPT port (parallel port), and some use parallel to USB converters (or parallel to serial and then serial to USB).

I'm looking at ways of developing a modification that will offer a USB connection for that control rather than parallel... but if the software won't recognise a USB connection then that's a stumbling block

[leenewtoastro]

got ya

[Pakmoto]

The mod I've just done requires no parallel circuitry, it's direct to serial where the serial port controls shutter and amp off through RTS and DTR, also using this mod requires less circuitry and components than the normal 4066 chip and parallel to serial route.

[leenewtoastro]

this has got me intrested in doing this mod too. if you don't mind the hijack malc.?

it would appear we can make a box with everything in. i.e cam and mods in a small pcb box. not only that also fit a usb to serial convert in there too so we only need 1 usb cable. which would be champion.

[malc-c]

The mod I've just done requires no parallel circuitry, it's direct to serial where the serial port controls shutter and amp off through RTS and DTR, also using this mod requires less circuitry and components than the normal 4066 chip and parallel to serial route.

Care to share this.... most of the sites I found seemed to use either the 74HS00 or 4066 and a parallel port control.... using serial is far more accommodating... and I'm curious as to something that uses less than the three components (4066 and a couple of resistors) and achieved both the LX and amp off mod...

[leenewtoastro]

Hi malc, there is a guy selling the spc900 lx'd with serial connection.

by default this would suggest that the typical lx imaging control softwares will see a usb to serial adapter plugged into usb (it must, come to think of it)

so all we need is what chip is used when using serial control not parallel.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=150572313647

[malc-c]

That's sold by the guy who's article is featured in Astronomy now.. yes these will work with serial to usb converters as the PC still sees this as a com port. I'm looking at programming an 18F2550 PIC micro which has a USB to handle the communications between the PC and 4066 chip. The only issue is that all the capture software that supports LX mode has probably been written for communication via the serial / parallel ports and not USB

[Pakmoto]

and I'm curious as to something that uses less than the three components (4066 and a couple of resistors) and achieved both the LX and amp off mod...

4066 method and parallel to serial uses a few more than 3 components, think you may have misread my original post,

But anyway, this is the tutorial I used to build my mod, Bolton Astronomical Society • View topic - Cheap Webcams

and here's the shopping list

5 x 10k resistors

3 x BC548 transistors

3 x 1N4148 diodes

1 x 1N5348 diode (ZD11V)

[Glider]

So, if I understand, you want to design a new USB device type to enable LX control rather than just use a USB to serial RS232 or USB to 3V or 5V TTL levels.

[leenewtoastro]

i'm sorry malc i'm not grasping it. you think just because you have a usb connection it won't work! that is exactly what the usb/serial adapter does. fools the software that it is connected to serial/parallel port directly. ???

[Glider]

Google for Sharpcap software.

[leenewtoastro]

you want ONLY usb connects to set LX?

1 possibility?

[Glider]

malc-c, when you plug the camera in you physically use 2 USB connectors.

One is simply the camera USB which carries power, and video. The PC sees this as a webcam device.

The other is a USB to serial converter that just controls the LX circuit. The PC sees this as a com port and in control panel it'll appear as something like com23 say.

In Sharpcap I imagine you just select com23 from the pull down list.

[Stephen]

Does the power not get split evenly between the two hub ports (resulting in loss of power to the camera?)

[leenewtoastro]

malc-c, when you plug the camera in you physically use 2 USB connectors.

One is simply the camera USB which carries power, and video. The PC sees this as a webcam device.

The other is a USB to serial converter that just controls the LX circuit. The PC sees this as a com port and in control panel it'll appear as something like com23 say.

In Sharpcap I imagine you just select com23 from the pull down list.

my understanding too

[leenewtoastro]

Does the power not get split evenly between the two hub ports (resulting in loss of power to the camera?)

power (or voltage) will be as normal on both usb ports

[Glider]

Though by using a 2 port powered from one USB connection on the PC you might struggle for current if the camera modification includes say a fan or some sort of cooling.

The 2 connection back to the PC approach can help under these circumstances as each connection can supply its own current.

[leenewtoastro]

all needs concideration. i use a high power hub that has plenty to each port.

especially with a fan involved much bigger current than the other devices require

.

edit: hmmm components rather than an ic for serial! hmmm ponders

struggling to see were 1 wire goes and what for too

could power for that board be derived from the cam usb power ( say if you had a serial that has no 5v+ )

is dtr txd or rxd?

.

[malc-c]

Pak:

Thanks for the link... the schematic using three transistors and handful of resistors to allow serial communications is very encouraging...and will give me an option as most PICs also have RS232 built in so it's a case of programming the PIC to do the Packet/BIT conversion.... maybe ! - If not then using a serial to USB converter is preferable than USB-RS232-parallel option

Glider:

Yes... basically I'm looking at having two USB cables coming out of a box housing the camera. One would carry the video signals as is, the other handle the LX (and possibly amp on/off) control. mainly as I only have 3 USB ports on the netbook. If I can't come up with an embedded solution using a PIC micro, then the alternative is to strip down an USB to RS232 converter and house the electronics in the case - which given that I only have a couple of weeks until SGL6 might be how I proceed ! - I have SharpCap installed so will look at that further, but yes most of these are set to use COMM or LPT so any PIC code will have to come up with some COMM port emulation

Lee:

That's a neat idea... but would be tight fitting the LX mod board, rs232 to USB converter board, and 2 port USB hub all in one small container... but I appreciate you contribution and it's something that may well be an option.

Thanks for all the contributions guys... lots to think about

[Glider]

It doesn't have to be complex or large.

[beamish]

someone has to ask- where did you find the lLX board Glider?