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TMS320F28027F: f28027

Ahsan
Intellectual 625 points

Part Number: TMS320F28027F

Hi,

I am going to implement f28027 on PCB and for on board programming, I will be using XDS110. I have mentioned the diagram of connection below. Is it fine or something has to be modified. Which type of communication will it do with the MCU.

One other question is that TRST compliment pin is connected with pull down resistor which means normally it will be connected to connected to ground. Is that the correct configuration?

  • 0
    TI__Guru* 82800 points

    Ahsan,

    In terms of the JTAG connection what you have is correct.  You want to include the Pull Down on TRSTn as you have shown, as this will ensure the test/JTAG logic inside the device stays in reset when the XDS110 is not active.

    I will also add that on this device TDO shares a pin with GPIO37.  This is important since GPIO37 and GPIO34 are the boot mode control pins for this device.  You should look at the boot configurations to see what potential options you'd like to enable for the device when it is free running w/o an emulator connection and make the appropriate population options available.

    Best,

    Matthew

  • 0 in reply to MatthewPate
    Intellectual 625 points

    Matthew,

    I have copied this schemetic as recommended by TI in JTAG modules. There is they have connected pull down resistor to nTRST pin and there seems no connection on GPI34 pin. Is that fine? You can find the connection side to MCU below. Which communication module will it use for communication with computer?

    Ahsan

  • 0 in reply to MatthewPate
    Intellectual 625 points

    One other confusion regarding this is regarding Tx and Rx pins which are mentioned on schematic of launchpad f28027f. While using xds110 for on board programming, don't we need these connection pins on pcb because I have not seen them on pcb configuration for xds110 ?

    Thank You

  • 0 in reply to Ahsan
    TI__Guru* 82800 points

    Ahsan,

    In terms of the emulation connection via JTAG you are good.  While GPIO34 is not a JTAG pin, it, along with GPIO37, control the boot mode of the device when the emulator is not connected.  So, there is no connection for use with JTAG, but when TRSTn = 0V(emulator not connected) the device will sample GPIO34/GPIO37 on the rising edge of XRSn to determine the boot mode of the device according to the link I mentioned previously.

    In terms of Tx/Rx pins on the XDS100v2 and XDS110 we are using a secondary channel to enable UART communications with the C2000 device.  This is not required for the CCS debug connection.

    Best,
    Matthew

  • 0 in reply to MatthewPate
    Intellectual 625 points

    Matthew,

    Currently I am using launchpad-f28017f and for this all the 3 switches has to be on for normal operation. But in the datasheet of f280127, it is written that TRST compliment pin has to be connected to ground for normal operation. Both should be correct in their own way but what could be the reason?

    Regards,

    Ahsan

  • 0 in reply to Ahsan
    TI__Guru* 82800 points

    The switch on the TRSTn pin is just an added safety measure to avoid having a snub/antennae on this pin when the debugger is not in use.  When running in standalone(no debugger connected) you want to make absolutely sure that TRSTn does not transition to logic high(3.3V) which would bring the test logic out of reset, but not under control.  The PD should be sufficient in any case.

    Best,

    Matthew

  • 0 in reply to MatthewPate
    Intellectual 625 points

    Matthew,

    Fine. Thank You for the information. What should be the position of all three switches during debugging?

    Regards

  • 0 in reply to Ahsan
    TI__Guru* 82800 points

    In this case I would put the device in Wait Boot mode.  TRSTn switch should be set to connected the signal to the pin header, GPIO37 = 1 and GPIO34 = 0.

    Best,

    Matthew