Hello,
I have another question on the Color Serial TTL level camera (Product code : RB-Lin-24). I’ve been looking at the datasheets and one of the reasons I’m going to be choosing it is because of it max frame rate of 30 per second compared to another camera RobotShop sells with only 0.75fps. My question though is with a max data rate transfer of 115200 bps how can it handle a 30fps rate at the resolution of 640 by 480 pixels? With that size image it comes out to (640480)(8 bits per pixel) = 2,457,600 bits per image (correct me if I’m wrong). How can the camera handle that frame rate with a low data transfer rate?
I’m guessing the company has yet to reply, but I was just browsing google and came upon this site
ladyada.net/products/camera/
It says the the camera outputs video through the video pin in NTSC format but the TTL level serial commands can request that the video be frozen so that the an image can be captured and sent at a data rate suitable for a microcontroller to be able to handle. I figured I could save some time.
I have a question though. It states that to output raw video feed you can solder on two more wires to the grd and cvbs terminals. Can a computer take in video feed from this camera or is it only suitable for a tv?
Ok thank you. So regardless of what I hook up to the serial line (be it computer or arduino) neither will be able to capture video because of the data rate limitation of the camera? I will check out video capture cards but considering the camera will be on my robot the only way to capture images is by wirelessly trasmitting them through arduino.
Couldn’t the xbee handle it. I’ve seen example code that comes with the documentation about sending the image serially to the computer. Couldn’t the arduino send the image wirelessly through the xbee, and if limited by data size, in packets?
Thats good to hear. One last question though about the data rate. Do you think that each pixel would be 8 bit considering its a color camera? If so is this calculation correct:
(640480)(8 bits per pixel) = 2,457,600 bits for an image.
2,457,600/(115,200bps max data rate) = 21.333 seconds to transmit one image through arduino?
And thanks a lot for helping me out. I noticed all of my posts were answered by you and quickly, so thank you for that.
Even better. Thanks a lot for all the help.
The 30 FPS @ 640x480 seems wrong indeed. Even if the image was heavily compressed, this would be roughly 0.5 FPS. We will confirm with the manufacturer and let you know.
We did not have a reply form te manufacturer yet, but they might indeed refer to the NTSC signal which is defined to be [email protected] FPS.
The NTSC signal is suitable for display units (such as TV sets) and can only be analyzed by a computer with a video capture card.
That is correct. If you want to transmit wireless video, then you will have to use an analogue video transmitter and receiver.
The XBee acts as a serial port so you should be able to send the frames wirelessly. Although they support the maximum serial speed, you might need to reduce it a little in order to prevent transmission errors, especially at long distances.
You must remember that this is a JPEG camera, so the images are compressed. From the Laydyada link you posted, I fetched the image size of one of the sample images: 45.94 KB
45.94 KB x 1024B/KB x 8b/B = 376 422.4 b @ 115 200b/s => 3.27 s
Glad to help!