[Elphel-support] [#692979] Board 10359

[Elphel Support List]

Andreas,

Can you please send the full list of parameters in that link you've sent? Or was it truncated by the mailing list software? - in that case send just parameters, not in the form of URL.

So you are first trying to set camera so the sensor will run in external trigger mode with the periodic trigger generated in the FPGA? There is a minor bug - you can not switch trigger modes when the timer is off (as it is initially). Even if you change it in the same command camera will get stuck as most logic is synchronized by the sensor frame sync pulses. So you have to make those pulses coming before you change the modes. Here is the procedure:

So on the page (linked from http://192.168.0.9/parsedit.php)
http://192.168.0.9/parsedit.php?embed=0.1&title=External+trigger+controls&TRIG=4&TRIG_PERIOD=19200000&TRIG_DELAY&EARLY_TIMESTAMP=1&THIS_FRAME=@&TRIG_CONDITION=0&TRIG_OUT=0&SENSOR_REGS30=@

1)Uncheck 'TRIG' line and click "Apply'. That will program the timer, but not switch to external trigger mode
2) Then - put "4" (as it was originally) or click "Restart" button.
3) click 'Apply' again - it should not freeze anymore.

The EARLY_TIMESTAMP parameter (used in external sync mode) switches between moments when the timestamp time is acquired. In regular (free running) mode it hap[pens at sensor frame sync (beginning of the frame readout) - it is OK as the exposure starts during the previous frame readout and changing exposure time does not influence the frame period. That is not exactly the case with external trigger mode - the start of the readout (and frame sync) will "float" with the exposure time that starts 8 scan lines time after the external trigger. So using timestamps of the frame sync causes the frame period (measured at start of readout) slightly variate when exposure time is changed (i.e. by autoexposure algorithm) and that can confuse video streamer. When EARLY_TIMESTAMP is set, timestamps use the trigger moment instead of the start of the readout - that results in constant frame periods.

Andrey