MATLAB: Do I get a ‘Failed to connect to target’ error when using External Mode with TI Delfino F28335 control card with a Peripheral explorer but not with a docking station

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I have a Texas instruments F28335 control card with a peripheral explorer and I am trying to make it run in external mode but I am facing an error as shown below:
"### Done invoking postbuild tool."
### Successful completion of build procedure for model: c28x_serial_ext
Build process completed successfully
action: EXT_CONNECT
Error:Error occurred while executing External Mode MEX-file 'ext_comm':
Failed to connect to the target. A time-out occurred while waiting for the connection response from the target. Possible reasons for the time-out:
a) The target is not switched on.
b) The target is not connected to your host machine.
c) The application for the model is not running on the target. You might have clicked the Stop button. If the Run button is not dimmed, click it. Otherwise, click the Build button, which downloads and runs your application on the target.
Error:Unable to connect to the 'TI Delfino F2833x' target for 'c28x_serial_ext'.
I am able to run the model in external mode with a docking station instead of a peripheral explorer. What can be the reason?

Best Answer

In this case it turned out to be hardware issue on the peripheral explorer side because of an incorrect schematic diagram. This is prevalent with all TI C2000 peripheral explorers.
The schematic for the Peripheral Explorer R5 shows that the USB-SCI path as:
-GPIO-28 -> USB_SCI_RX -> RX
-GPIO-29 -> USB_SCI_TX -> TX
However, it should be:
-GPIO-28 -> USB_SCI_RX -> TX
-GPIO-29 -> USB_SCI_TX -> RX
You can rework the board by cutting these traces and adding some wires to make the correct connections. Please see the corrected schematics attached with the article.
Texas Instruments have logged this as a hardware bug, however, since the board is relatively stable, it may be a while before a revision occurs.
Please refer this link from Texas instrument's forum describing this issue:
https://e2e.ti.com/support/microcontrollers/c2000/f/171/p/134600/487000
In addition, check your hardware connections along with the settings made on the software side such as baud rate and clock frequency which can also cause similar errors. These are general debugging steps for external mode failures.
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