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D4100 signal indicating mirror reset

Justin Aluko
Prodigy 60 points
Other Parts Discussed in Thread: DLPC410

Hello,

I am using the Discovery D4100 controller board to control a .7" XGA DMD. I want to use the DMD to send a signal to a separate detector telling it to start a new measurement when the display in the DMD changes (even if it is only a single pixel).

I have played around with the GPIO connector to send a trigger when the display changes which works, however since the command is being sent via custom code using the standard developer kit DLLs, there is a significant delay between the display changing and the trigger being sent which is seriously affecting the measurements being made. I think that this can be improved to some degree by tweeking the architecture of the code, which I am in the process of doing, however I am aware that OS interrupts will still occur.

I would ideally like to send a signal straight from the D4100 board itself independent of the operating system, every time it receives a reset command. I do not have the expertise to reprogramme the FPGA to do this. Is anyone aware of a clocking signal that is at least 2.5V (TTL) that can be re-routed from the board itself to fulfil this purpose? Even better would be if someone has already managed to change the FPGA code to automatically trigger one (or more) of the GPIO pins upon reset and doesn't mind sharing it? 

Thanks so much for reading this, any help will be greatly appreciated!

Justin

P.S Do not worry about withholding solutions that would void warranty since the device is out of warranty anyway.   

  • 0
    TI__Guru 54175 points

    Hello Justin,

    There is one possibility, to use the RST_ACTIVE pin (AB16) from the DLPC410 (not the APPS_FPGA) which signals the APPS_FPGA that a µ-mirror clocking pulse (MCP - sometimes called a "mirror reset") is in progress.  When it goes low this could be used as a trigger your device.  Actually you should wait about 8 µs after it goes low to start your measurement, but it will always have the same relationship to the MCP. 

    As noted this trigger will be slightly early, but depending on your measurement system, there may be more that 8 µs of lag between receiving the trigger and starting the measurement.

    I hope this helps.

    Fizix

  • 0 in reply to Fizix
    Prodigy 60 points

    Hi Fizix,

    Thanks so much for your prompt reply! It was very helpful indeed.

    I have had a look at the documentation for the DLPC410 and the pin looks like its incredibly difficult to get to, made even more so by the fact that I am far from an expert in electronics (barely a novice to be perfectly honest). Unless I am misunderstanding something, which is likely, I would need to get under the FPGA that configures the DLPC410 device to get access to the pin before I could solder on a cable to re-route the signal. This isn't something I can do without completely breaking the device. Judging by the DLP Discovery 4100 Technical Reference Manual, there also doesn't seem to be a connector, JTAG, GPIO, EXP or otherwise, that I can use to get access to it instead, unless I have missed something. 

    Do you know of any another ways to access this pin?

    Thanks again for your help,

    Justin 

  • 0 in reply to Justin Aluko
    Prodigy 60 points
    In typical fashion I answered my question as soon as it was posted. I found a question from last year, titled "DLPC410 RST_Active to DMD flip delay", where you clearly show how to get access to this pin.

    Thanks again for your help!

    Justin