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CCD line sensor outputs clean square wave

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m98:
Hi,

I'm trying to read out an EPC901 CCD line sensor, applying the proper read clock after a shutter pulse when the data ready pin goes high.
But on the video output pin, I get a perfect square wave (note the probe ground is attached over a long lead)

Schematics:


Any ideas on what could cause the sensor to generate this output?

Thanks

m98:
Ok, so I already found out why the sensor didn't respond to light, clearing the pixel buffer before capturing an image really isn't optional, and I accidentally disabled the GPIO pin responsible for that signal. Now every second pixel does seem to respond correctly, but the output still goes low every time in between. Also saw that I accidentally have 2 pixel binning enabled over the configuration inputs, so I explicitly disabled it via I2C. But the datasheet even states that binning reduces the amount of neccessary read clock pulses by the binning factor, so when factor 1 requires 1024 + 3 clock cycles for a full readout, factor 2 only requires 512 + 3, with the data ready signal going low after a full readout. It did only go low after the full 1027 cycles.

... Turns out the datasheet is probably wrong, or incomplete. Forgot to set the configuration enable bit, so now that the I2C configuration actually has an effect, and pixel binning is disabled, the issue is gone and the sensor works as expected.
At least I've now found a method to verify the video amp bandwidth without using a shadow mask on the sensor  :-//

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