Elphel Development Blog

10359 Stereo: Dealing with phases

There’s a nice page on Elphel’s wiki describes the problem: Adjusting sensor clock phase (the last paragraph is outdated, the script is in the ‘attic’, and I couldn’t find an alternative in the new 8.x firmware).

It was difficult to adjust data phases for long cables (& sometimes even for short) connecting sensor boards with 10359. To do it in a more or less automatic way a php script ‘test_inner_10359.php’ is used, which in its turn uses ‘phases_adjust.php’ with 5 phase steps at a time and compares the MD5 sums of the frames with the known one at defined sensor parameters.

So far, the solution is:

1. The problem was with the sensor on J2 mostly. In 10359 project that sensor is clocked through the BUFG (idclk) by the clock coming from 10353 (DCLK) . After inverting it the things got better – and this is luck.
2. In ‘phases_adjust.php” changed the number of phase steps taken from 5 to 2 to increase the precision. And it worked =) – 5/5 for the camera in the office.

TODO:

1. Add an “AUTO” button to 10359 interface page.
2. Modify standard (in prod353) ‘test_inner_10359.php’  to be able to work with only 2 sensors.

HOWTO:

• go to: http://<camera-ip>/359/10359_controls.html

PS: Also tried to add a bit mask to data bus from the sensor just to find out whether the data bus changing time exceeds the period but the picture became unstable every time the phase was close to the correct one.