Society of Robots - Robot Forum
General Misc => Misc => Topic started by: Joker94 on May 29, 2010, 06:18:48 AM
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Hi guys
Do you know what the maximum frame rate of the Black fin is? or can be! From what i have seen it doesn't go much further than 5 fps.
for what i need to do i need a UART input so i should be able to connect the Blackfin from UART to UART. The only thing i need to know is what the maximum framer rate is.
Cheers
Joker94
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Do you mean the frame rate of the camera hardware it uses - or how many frames per second can be sent out over the UART to microcontroller/PC.
If its the first then check the datasheet of the camera hardware they use.
If its the second then it will be very slow. ie at the lowest resolution (160x120) then thats 19,200 pixels per frame. Assuming each pixel has a byte for each of red, green and blue then its 57,600 bytes. So at 115,200 baud it will take around 4 seconds to send a single frame. Thats why nobody ever does it! Rather they write their image processing logic into the chip on the Blackfin board and just send the results over the UART. Even if the UART ran at infinite speed - where are you going to store the 57k of data for each frame?
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Thanks Webbot
It has been decided that we are going to use a analogue transmitter and not bother about integrating the camera into the auto pilot.
thanks for your help.
I'll post the solution we use in the next week or two.
Joker94
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Joker -
As Webbot notes, it depends on resolution, but also the speed of the serial interface. The SRV-1 Blackfin transmits JPEG, and a typical 320x240 frame is 5-10kbytes (40-80kbits), so after you add compression time (25 fps), at 115kbps you end up with 1-2 fps. If you have a higher speed interface such as Matchport wifi which runs at 2.5Mbps (actual throughput closer to 1.7Mbps), the frame rates at this resolution end up closer to 10-15fps range.
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I need 20 + so we are going with a standard AV camera. No need for what the blackfin has
Cheers
Joker94
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Joker -
As Webbot notes, it depends on resolution, but also the speed of the serial interface. The SRV-1 Blackfin transmits JPEG, and a typical 320x240 frame is 5-10kbytes (40-80kbits), so after you add compression time (25 fps), at 115kbps you end up with 1-2 fps. If you have a higher speed interface such as Matchport wifi which runs at 2.5Mbps (actual throughput closer to 1.7Mbps), the frame rates at this resolution end up closer to 10-15fps range.
I wanna to ask if I use xbee what's the maximum frame rate I can get? another question I just have to define the baudrate for the BF and the xbee only rite? or do I need to send some commands to the xbee? thank you
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If you want a wireless system, just buy a wireless camera for $50. The blackfin is designed for on board video processing, so it is kind of pointless if you dont do the processing right where the camera is.,
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I'm doing onboard processing and at the same time I wanna send the image to the PC tru wireless mesh xbee. The problem is the frame rate pretty slow, without transferring the image the processing time 10fps while when I include image transfer it takes like 1-2fps. Is there any example code tat allow parallel processing like using DMA uart?