Other Parts Discussed in Thread: TFP410, SN74LVC244A
I am testing a board fitted with a TFP401 chip. I am transmitting a series of test patterns to the board using DVI at 1280 x 1024 @ 60hZ from a QuantumData 780C video generator. The parallel output data from the TFP401 is taken from the test board via a parallel cable to a second circuit board where the data is buffered by SN74LVC244A octal buffers then converted back to a DVI signal by a TFP410 chip.
The issue I am seeing is that when the output of the TFP410 chip is connected to a monitor, the screen is mostly black and flickers occasionally. The set-up does function, I can see the transmitted data patterns on the monitor with output settings of up to a screen resolutions of 1280 x 720 @ 60hZ, but anything above this does not display. The ODCK is running at 108.9MhZ when
A couple of questions:
- With the ST pin of the TFP401 pulled high, setting the drive outputs to high strength, what is the maximum length of track that the 1280 x 1024 @ 60hZ could be expected to be driven down and still arrive as a valid signal? I am currently using a longer parallel cable than planned, and will be moving to a shorter length when it becomes available but at the moment, the length of parallel tracking between the output of the TPF401 and the SN74LVC244A octal buffers is about 30cm. Between the output of the octal buffers and the input of the TFP410 is about 1cm.
- The webpage for the SN74LVC244A octal buffers rates them as capable of 200Mbps. Is this per data line, or spread across all eight data lines? (i.e, each data line can transmit at 25Mbps and all eight lines make up the 200Mbps).
If the above questions are not the cause of the issue, what would be other areas to investigate?
Cheers
Phil