Transplanting an electronic viewfinder and sending a signal to it - Page 1
Forum section: electronics / projects

author: Recyclojunk64
author_rank: Contributor
timestamp: February 24, 2014, 11:45:37 am
content: Hi all. I'm working on a project involving two cameras (Canon SX40's) for stereo-photography. Using CHDK of course. The SX40 model, being a "bridge" camera, has an electronic viewfinder, so I figured that I might as well turn that into a stereo-viewfinder by mounting the viewfinder from the "slave" camera on the side of the "master". That way I will be able to easily frame my shot and ensure that the cameras are aligned properly. It'll also help ensure that the stereo-base (the distance between the cameras) is reasonable.However, the EVF has 21 wires going to it unfortunately. Since the cameras may be some distance apart some of the time, this is going to be a problem.The viewfinder is pictured below. The resolution is 202k-dots (yeah it's pretty lame I guess). The chip reads RL461227W, and a datasheet search falsely turns up either a 3-pin voltage-regulator or a large 12V SLA battery, of all things. It seems to have no connection to the RGB LED, which isn't connected to the input wires either. The rest is potted.I have looked at the signals going to it on the scope, and there seems to be 8 parallel data lines (2.6V high), aswell as a 27Mhz clock, 59.94Hz v-sync and a 15.73Khz h-sync signal. There is also 4.9V, 3.3V and 2.6V power rails going to it, although I don't mind stealing power from the master camera to run it. So that's 12 wires (11 data and one gnd) minimum.So I'm not really sure what to do. I have no idea of the output impedance of whatever's sending data to the viewfinder, so I don't know if capacitance between the wires in a cable will be a problem. The cable will have to be at least 1 to 2 metres in length. And not ridiculously thick either. Is this in any way feasible?What I would prefer to do though would to convert the signal to serial or something that only takes up one or two wires, and can be extended to a larger distance of up to maybe 10 metres. Through either a coaxial or twisted-pair cable. The signal would then need to be converted back to how it was with the V-sync and H-sync signals aswell. Any idea of a device that could be modified or a chip that may do this? Or a device or chip that could convert composite video (which the camera can output) to a parallel output similar to this, taking into account that the viewfinder has less resolution that normal composite video.Even better would be a solution to wirelessly transmit the signal, using maybe 2.4 Ghz.Any ideas?

author: amyk
author_rank: Super Contributor
timestamp: February 24, 2014, 12:34:19 pm
content: That RL46 is a 93L46 EEPROM made by ROHM.http://rohmfs.rohm.com/en/products/databook/datasheet/ic/memory/eeprom/br93lxx-w-e.pdf(page 34)

author: ajb
author_rank: Super Contributor
timestamp: February 24, 2014, 06:15:57 pm
content: Looks like the SX40 has composite video out. It would likely be much easier to run the composite outputs to a pair of small displays rather than to try to extend that tiny flat flex ribbon, that way you also keep the cameras 'stock', for whatever that's worth to you.