PCIe 6535 connection to Analog front End

[erhk]

I have CCD image sensor and its output is connected to AFE (TI 2562). The output of AFE is digital data (12Bits @ 9MHz) which then goes to FPGA. I have PIC controller for controling image parameters. At the display I can see the NTSC video. Now I want to test something on the digital data coming out of AFE (12Bits @ (MHz) So I just bought PCIe 6535 board to capture those data to my computer. I am using C68-C68-D4 Unshielded Cable and CB-2162 Single-ended Digital I/O Accessory to connect my device to computer using PCIe board. I had manually connected my AFE output lines(12 Bits + 3 sync ) to the CB-2162. I am using my device as a monocular. I can see video at the display under normal condition when CB-2162 is connected but when I connect C68-68-D4 cable to CB-2162 video stucks at the last scene. Do I need use buffer in between my device and CB-2162 ? why this happens?

[NathanS]

It sounds from your description like the signals being output from your AFE are going to the FPGA and also to the PCIe 6535. If that's correct, you may have created a voltage divider. The input impedance of the PCIe 6535 is 50 kOhms, which could significantly reduce the voltage at your FPGA; if the voltage at the FPGA is too low it may not be able to read the signal.

You could try balancing the impedances with a resistor.

Just a thought!

Regards,

[erhk]

yes, output signals from AFE are going to the FPGA and also to the PCIe 6535. I don't have any resistor between AFE and FPGA. Along with my 15 different signal line that I had connected from AFE to my connector block (CB-2562), I also had connected ground line from AFE to CB-2562.

How can I do impedence balance??

Thank you,

[NathanS]

Thanks for your post! I wanted to let you know that we will continue to help troubleshoot this issue through the service request you currently have open with our Support department. Also, please disregard my previous suggestion concerning impedance matching; my colleague pointed out to me that this problem is unlikely to be a voltage divider issue since the devices are in parallel. Thank you.

Regards,