Timing chart of LED_EN and Grab signal

Hello Han,

DisplayPatternAutoStepForSinglePass API is like a software trigger of displaying pattern sequence. It cannot be used with External trigger i put this information because in your above waveform you have put the Trigger (Input) signal and also mentioned DisplayPatternAutoStepForSinglePass. You can use either of them but not together.

If I read your description, basically you are interested to display sequence of patterns with 2ms dark-time in between them, is it correct? Two options to trigger (a) External Input Trigger or (b) DisplayPatternAutoStepForSinglePass API Call..

Answers to your question - 

#1.

It is possible to configure DLPC200 to O/P LED_EN like this with slight modification. As shown in the picture below the the first 2ms will be approximately 200us from the trigger input. After this everything will be as per yours description i.e. 2ms OFF and 8ms ON.

If it meets your requirement then you need to do the following configuration to the system. Please find GUI snapshot

#2

Answered in #1 above.

Regards,

Sanjeev 

Hello Sanjeev,

Thanks for your reply.

Yes, I like to display 8 patterns in sequence, 2ms dark-time between them.

I stored 4 set of patterns in flash memory and each pattern set has 8 patterns.

I select one pattern set and display sequence of patterns above

And After displaying them, I want to turn off.

1. If I use external trigger source, is this possible to display ?

    I guess it seems to be displaying them continuously.

2. And please explain LEN_EN and LED_RED_EN in details.

    The waveforms of two signals seems to be little bit different.

3. I use SYNC_0 signal for the Grab signal above picture

    In this case, setting the 2000us delay and 8000us pulse width value is correct ?

    I am confusing the delay value, 0us delay or 2000us delay.....

Regards. 

Hello Han,

1. Yes you are correct with the external trigger signal the patterns will be displayed continuously. In your application I suggest to use the software API DLP_Display_DisplayPatternAutoStepForSinglePass () also make sure you set the pattern trigger to AUTO. so when the API is called it will display patterns once and stop. I presume you are already aware of loading different solutions from the flash if not it is discussed here http://e2e.ti.com/support/dlp__mems_micro-electro-mechanical_systems/f/387/t/188164.aspx

2. LED_EN as per DLPC200 datasheet is DLPC200 I/O No. L28, is an ACTIVE low signal. This is used to turn ON or initialize the LED Driver board. LED_RED_EN is a signal going to LED driver to indicate when to turn ON the RED LED.

3. SYNC_0 is to a user programmable marker (pulse signal) to indicate when the pattern display starts.This is marker signal and it is not meant for using it for pattern exposure time. As per your description in the beginning, I suggest you to access the LED_RED_EN or LED_GREEN_EN or LED_BLUE_EN signal.

Regards,

Sanjeev

Hello Sanjeev,

Long time no see.
I have another questions on above timing
When I give the trigger command DLPC200, SYNC_0 and RED LED signals are activated with some delays
The delay time is vary from time to time, around 1 msec to 30 msec.
This is very serious issue on me
As you might know, our board give SPI command to DLPC200 instead of H/W trigger.
I set the auto trigger generator in trigger source menu in control S/W.
Why do DLPC200 have delay times irregularily ?
And what's the meaning of software trigger in trigger source menu ?

Please give me the answer ASAP.

Regards.

Hi,

Are you referring to GenerateSWVsync (0x0034) command described in the DLPC200 SPI Command Interface document?

Also if you are sending any other commands everytime before sending GenerateSWVsync (0x0034) let us know...

Regards,
Sanjeev

Hi Sanjeev,

My main question is the start time period of pattern display after trigger signal
When I sending DisplayPatternAutoStepFor SinglePass command, it starts to display pattern right away sometimes.
Sometimes, the pattern displays in few msec and also it start to display pattern in 20~30msec.
Is this related with GenerateSWVsync (0x0034) command?
Please explain me in details.

Regards

Thanks for clarifying, it is not related to GenerateSWVsync command.

About DisplayPatternAutoStepForSinglePass -

There are discussion on the forum here

https://e2e.ti.com/support/dlp__mems_micro-electro-mechanical_systems/f/387/p/228263/811229

https://e2e.ti.com/support/dlp__mems_micro-electro-mechanical_systems/f/387/p/228263/821578

As you see from the above threads, the API functionality is internal VSYNC driven, so after receiving the command, the actual display depends on the arrival of next internal VSYNC interrupt,  with this the worst case can be a full VSYNC period. 

I hope this explains the behavior.

Regards,

Sanjeev

Hi Sanjeev,

My understanding is as belows.
Once receiving DisplayPatternAutoStepForSinglePass command, internal VSYNC is driven in DLPC200.
and the internal VSYNC driven time is not constant.
Am I right?
If yes, is there any other solution to keep the constant timing from receiving command to internal VSYNC ?

Regards

No. Internal VSYNC is always running at the fixed period. So internal VYSNC is not a problem.

When a command is received, you don't know exactly where DLPC200 is in, so after receiving the command, it has to synchronize to VYSNC, it does only on the following VSYNC, that is when it starts displaying patterns from DisplayPatternAutoStepForSinglePass command.

There is no way to synchronize command to internal VSYNC so it is not possible.

I hope this explains.

Regards,
Sanjeev

Thanks for your explanation
Can I know how much period time internal VSYNC occur?
If I send GenerateSWVsync(0x0034) right after DisplayPatternAutoStepForSinglePass, does it work?

Regards.

Can I know how much period time internal VSYNC occur?
>> This depends on the LED Illumination Time (Camera Exposure Time) set while building the Project in the GUI tool.

If I send GenerateSWVsync(0x0034) right after DisplayPatternAutoStepForSinglePass, does it work?

>> No. Both are two unrelated things, DisplayPatternAutoStepForSinglePass uses "internal" or auto-trigger option to display patterns once. While GenerateSWVsync a software command equivalent to one external trigger signal.

Regards,
Sanjeev

Thanks for your kind replies.
How about just sending GenerateSWVsync command ?
Does it display patterns on flash memory ?
if not, is there any other method to project the patterns on flash ?
What I want to know is the way to display patterns on flash immediately by some trigger input.

Regards

Hi Sanjeev.

Regarding above question,
the control S/W user manual on page37(Table 7.2) tell me that the last three signals can only be used in Structured Light Mode, when the Static Image Buffer is selected as the active source.
So, I triggered to DLPC200 by external 3.3V trigger and software trigger, the patterns were not displayed though.
What do I doing wrong?

Regards.