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TMS320F28388D: The on-chip ROM USB peripheral bootloader of Rev. B controlCARDs do not seem to work

Part Number: TMS320F28388D
Other Parts Discussed in Thread: TMDSCNCD28388D

Hi,

We have three TMDSCNCD28388D controlCARDs: two Revision B (MCU063B) card and one Revision A (MCU063A) card.

While the Rev. B cards run the various code examples without issue, we encountered issues when we tried to force it into USB peripheral boot by erasing all the Flash Memory of CPU1 (while leaving the boot mode selection configuration in the factory default state). At the very least, we expected the controlCARDs to successfully enumerate with the Windows 10 host PC. Instead we kept running into "USB device not recognized" errors. We also tried changing the emulation boot registers while debugging to make it perform a USB peripheral boot in hopes of a different result, but there was no change.

This is strange because in the Rev. A card was no such issue. It successfully enumerates with the VID 0x1CBE and PID 0x00FF; regardless of driver installation status. We suspect that it may be due to the clock speed difference between the two controlCARDs (Rev. A uses a 20 MHz clock input, while Rev. B uses a 25 MHz clock input) that the on-chip ROM USB peripheral bootloader code failed to take into account. We are currently considering a possible solution where we modify the Rev. B controlCARD clock speed by un-soldering and re-soldering a specific resistor on the PCBA according to the instructions provided by Figure 2 in the TMS320F28388D controlCARD Information Guide.

However, if we are mis-informed about the nature of our problem or if you have a much better solution, please reply as soon as possible. Thank you.

Sincerely,

Howard Li

  • Howard,

    you have correctly determined the problem. Please move the resistor as described in the controlCARD information guide and the boot loader should work fine.

    I have created a request to have this explicitly called out in the documentation.

    Regards,
    Cody