Greetings,
I have an RGB Spatial Light Modulator (SLM). It is actually monochromatic but displays sequentially the three primary color image frames at 180Hz so the eye sees a colored image.
From the electronic driver of the SLM I get three trigger signals, one for each color. Each trigger pulse is ON for 5.6ms (ie. the duration of one frame of a given color) at a frequency of 60Hz.
Now for my need: I need to switch the Red, Green and Blue LEDs ON for a one-time, adjustable, single exposure, then switch them off for good.
So for a given color and a switch ON total time of, say, 15 ms, I would have to switch it ON first during 5.6ms (one frame duration), then off until the next trigger pulse of that color, then ON for another 5.6ms, then off again, then ON for another 3.8ms (ie. not an entire frame), then switch the LED OFF for good.
I need to programmatically be able to vary the exposure time, so I was thinking of using an Arduino, here is my idea but not sure this is the best/simplest:
- For a given color I tie a digital output of the Arduino, say D0, with the trigger signal of the SLM for that color using an "AND" external IC. The output of the AND IC goes to the LED driver to switch it ON/OFF
- The trigger signal is also fed into an input hardare interrupt of the Arduino.
- In the Arduino, knowing the exposure time, I calculate how many interrupts that should correspond to (Three in this case, the third one being a partial exposure of 3.8ms).
- At execution time, I set D0 to ON, then count the number of occurences of the input trigger. When reaching the third one, I perform a micro delay of 3800 microseconds before switching OFF D0 for good.
Will that work...? And is this the simplest most efficient way of doing it?
Thank you
Loic