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DLP780TE: D5 & D6 doesn't work

kent gu
Prodigy 50 points
Part Number: DLP780TE
Other Parts Discussed in Thread: DLPC4420,

Tool/software:

Hi
We designed the board base on DLPC4420 demo design and previous 660 drive board,  to drvie DLP780TE DMD. Have run for over 20 sample boards, all work well. Now enter mass production stage, found several board doesn't work. These boards' power are good and DLPC and FPGA FW version are right. But the D5, D6 and USB doesn't work intermittently(D5 flick, D6 off with USB and D6 on without USB). We suspect solder issue cause it. Base on the schematic, D5 & D6 LEDS are drived by U8 via I2C. I2C connect to FPGA and DLPC
Want to define which chip solder issue, so my question is:
#1, If D5 & D6 doesn't work, is caused by FPGA or DLPC?
#2, If DLPC, is it master DLPC or slave DLPC?
#3, USB doesn't work, is it reltaed to master DLPC?
#4, If HW are good, is relted to FW?
Best Regards,
Kent
  • 0
    TI__Guru 54635 points

    Hello Kent,

    Is D5 flickering like a poor connection or is it flashing periodically (i.e. a heartbeat)?

    D5 and D6 are I/O from the DLPC.  D6 sounds like it is working correctly, since off means connected and on means not connected to USB.

    Therefore, likely if both D5 and D6 are not working it is power or the DLPC.  The primary controller is responsible for these LEDs and the USB connection.  Since USB is mediated by the primary controller that is where to check.  It could also be a corrupted bootloader.  In that case it would have to be re-flashed over JTAG.  In other words it is possible that it could be related to the FW.

    Definitely check that your power switch has a good connection.

    Fizix