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DM365 RESET and TRST pins

Michael16400
Intellectual 515 points
Other Parts Discussed in Thread: TMS320DM365

Hello,

I was wondering what is the recommended layout to connect TMS320DM365 RESET and TRST pins?

It is said in the datasheet (p. 206) that:

While both TRST and RESET need to be asserted upon power up, only RESET needs to be released for
the device to boot properly. TRST may be asserted indefinitely for normal operation, keeping the JTAG port interface and device's emulation logic in the reset state.

In other words, should I put pull-down or/and pull-up resistors on those net? What if I want to use a button to reset the device?

Thanks,

Mike

 

  • 0
    TI__Guru 64440 points

    Michael said:

    It is said in the datasheet (p. 206) that:

    While both TRST and RESET need to be asserted upon power up, only RESET needs to be released for
    the device to boot properly. TRST may be asserted indefinitely for normal operation, keeping the JTAG port interface and device's emulation logic in the reset state.

    In other words, should I put pull-down or/and pull-up resistors on those net? What if I want to use a button to reset the device?

    I would suggest a pull-down resistor on TRST to keep the emulation logic in reset during normal operation.  A JTAG emulator pod will drive TRST high when connecting to the target.

    For RESET, I would suggest a pull-up resistor.  Your switch (button) can then be connected to RESET and the other terminal to ground.

  • 0 in reply to BrandonAzbell
    Intellectual 515 points

    Thanks a lot for the answer.

    Now, on p.82 of the TMS320DM365 datasheet, under the title "Timing Requirements for Reset" there are some timing requirements. Does it mean that I have to use Capacitors to produce that kind of signal, i.e. a delay between the reset signal and the bootsel?

    Also in chapter 6.4.1 there is a specific sequence to supply the power to the main/PRTCSS/ I-O parts: should it be done in hardware or software? Again, should I put some capacitors so there is a delay between "Power on the PRTCSS/ Main core (1.2-V or 1.35-V)." and "PoweronthePRTCSS/MainI/O(1.8-V)." for example.

    Regards,

    Mike

  • 0 in reply to BrandonAzbell
    Prodigy 190 points

    Thanks for this answer. I agree with TRST, but the CPU has an internal pull-down. Could I just hook up the JTAG line directly to the pin, then?. Also, if you're following a power-on sequence, would you just tie the RESET to the supply which is the last to power on? That is, the DM365 requires 1.2V, 1.8V, 3.3V, in that order. If I just tie the RESET up to 3.3V, would that work? It would just be low until all of the supplies are powered on, so I would think that it would... Thanks in advance.