CMOS based compact camera module

[chakkaln]

We are working on a project that involves building a CMOS camera. We are looking at a 1/4" sensor. We could identify a source for the sensor, however, they do not support the microprocessor assembly. what I want to know is where can we find information for building a camera, the circuit diagram and the raw materials for that. We are surprised that it has turned out to be more difficult than we initially thought it would be.
Any help regarding this would be highly appreciated.
Kind Regards
Chakka

 

[Blueteeth]

Well, generally CMOS camera's have some form of onboard circuitry to help the host system retrieve the data, with frame sync, horizontal sync, and bit clock. I imagine most manufactureres use ASIC's for dumping the data into RAM so a host system can access it, but I'm sure a large CPLD, or an FPGA could do the job.

If you're not experienced in this field, its a steep learning curve, there are plenty of CMOS camera modules around, many with onboard controllers. But what are you connecting this to? Are you after composite video out? MPEG video? still images? Such a project can easily balloon into a vast system, so many resort to using a PC and a cotrnoller card... but thats the easy way out, expensive, and over kll

More info on the app, and you might get a better answer from someone else.

BT

 

[chakkaln]

Thank you for your response. The requirement is to make an intraoral camera. A lot of them exist in the market but could not get the technology from anyone. So we started working on it ourselves. We have found a lot of resources for the CMOS sensor. However, they are unable to provide any information about digital signal processing. We need a sensor, looking at 1/4 inch CMOS sensor with 1.3 MP resolution. We then need a DSP to process the data to be transmitted to a display monitor. We are finding it hard to decide about the DSP. Any information/available circuit diagram for us to start the research will be highly appreciated. Thanks
Chakka

 

[Blueteeth]

As my knowledge of specific CMOS cameras is limited (I sort of know a little about many things, but no actaul experience here) I googled a bit. Found some references to various projects and a datasheet for a specific device.

CMOS Camera Module - 640x480 - SparkFun Electronics - cheap module, sparkfun have a forum for all their products, and the projects people use them for. No doubt you'll find some great interface info here, albeit probably for 'still' images.
**broken link removed** (my favourite site)
https://www.electro-tech-online.com/custompdfs/2011/01/xapp390.pdf (for raw digital elements)
Digital Project -- Digital Camera Interface
https://www.electro-tech-online.com/custompdfs/2011/01/ov6620DSLFPDF.pdf - typical datasheet for B/W basic CMOS module.

I was quite surprised to se that even a relatively low resolution CMOS camera has a lot of on-board electronics. With most camera functions controlled digitally via a simple I2C interface, and it has on board analogue to digital conversion. So it actually outputs a standard digital YUV interface.

Do you have a part no. for the sort of device you were looking at? I imagine it has similar on-board analogue/digital processing for a standard output. For an 'intraoral' camera, of course the camera element itself has to be small, as well as any interface circuitry to condition the signals (and to reduce the number of connections needed - so you don't have a massive fat cable connected to it) to a 'box', which could then contain any larger devices for heavy DSP.

I haven't seen any camera modules which can output a simple RGB analogue signal, which would reduce your connection count considerably, and push the complexity into your external 'box'. But, if it has a 24-bit RGB/YUV output, there are some LVDS serialiser IC's which can reduce these 24 lines to just 3. It is a question of how you partition the design between the hand held device, and the external 'box'.

Please explain further on what digital signal processing you require. If you simply wish to 'display' the image, then little DSP will be required, and some specific non-programmable IC's may do the job. If you want something like image recognition, on screen display etc.. then I imagine even a basic DSP could handle it.

Sorry if I'm probing here, and asking too much about your project, but there are many ways to do things, so the more specific the problem, the more specific the solution.

BT

 

[chakkaln]

Thank you very much for your support. We have looked at two different CMOS sensors, one manufactured by OVT (ovt2640) and the other by Truly semiconductors (https://www.electro-tech-online.com/custompdfs/2011/02/13M20CM3587-O130BF-E20Spec.pdf). Both of these give YUV as output. Our understanding is that we should be able to wirelessly transmit YUV data.
You have correctly assumed the requirements for our project, that is a compact sensor to go into the corners of the mouth, a few lines as possible between the head of the camera device and the handle. Your suggestion to cut down the lines from 24 to 3 is quite interesting and is something we really wanted to do. Can you throw more light into it?
If a sensor chip is able to generate a YUV data output, do we still need a DSP before the wireless transmission of data?

our area of interest deals with the wireless transmission of processed video output(color) over a WLAN through a mini WiFi transmitter,so that the signals are received by the wireless receiver for display on the tv and pc monitor.we are also intending our signals transmitted wirelessly to be compatible with WiFi enabled mobile phones and display devices.we are considering the YUV 4:2:2 format for interfacing with mini wireless transmitter. we look to reduce the output to minimum possible lines for interfacing with wireless transmitter. ovt 2640 output is not clearly specified as to number of lines and pin layout in case we need to interface this to our mini wireless transmitter ,we need the information to obtain the composite single output to enable it to interface with the mini wireless transmitter.

I have attached the picture of a chinese made intraoral camera which can be bought for about 25USD not including the wireless transmission