In the dlpu04a documents, there is some hint about the exposure time range, eg. for 8 bit depth the exposure time lists is between 8333us to 20ms Or, for 1bit depth the minimum trigger period(exposure time) is 250us.
And in your control software, when i set the exposure time higher than maximum value (e.g. 2sec for 1bit, or 20ms for 2bit), the command did failed. While when the exposure time setting is smaller than the minimum value(but not 0), the command success. My first question is can you tell me what the firmware will do when exposure time setting is smaller than the minimum value?
My second question is for the trigger period and trigger delay, is there any limitations on these two values? It seems no matter how long the trigger period i set, the command always succeeded. While the true period is not what i set to. e.g. the trigger period is set with 10 second, while the light crafter does not output the pattern in 10 seconds period.
Hi Natty,
The Exposure time is the number of us the pattern is displayed on the screen while the Trigger Period is the delay between two consecutive patterns. Since there is a slight delay between the trigger received and pattern projected, the trigger period should be always set slightly higher than the Exposure time. Or the GUI automatically adds additional 250us to trigger period.
1) My first question is can you tell me what the firmware will do when exposure time setting is smaller than the minimum value?
When the exposure time is set to less than the minimum value, the min. exposure time is added automatically based on the bit depth. The GUI allows a min exposure time of 'zero' only for 1-bit depth patterns.
2)My second question is for the trigger period and trigger delay, is there any limitations on these two values?
The minimum trigger period is 250 us, since the FPGA needs a load time of 250 us to upload patterns in to the mddr (mobile circular buffer). The trigger delay can be set as shown in the timing diagram above.
3) It seems no matter how long the trigger period i set, the command always succeeded. While the true period is not what i set to. e.g. the trigger period is set with 10 second, while the light crafter does not output the pattern in 10 seconds period.
In reality, when you set a trigger period of 10 us, the actual trigger period changes to (10+250) us.
Hope this helps!
Regards,
Divya
www.ti.com/mems
Hi Divya, thanks.
【the trigger period should be always set slightly higher than the Exposure time. 】 - is there any exact value to define the slightly higher?
As I mentioned above, it is the pattern load time to FPGA (250 us).