TMS320F28386S: Using CROSSBAR to route input signal for SSI and UART

Hello Oleg,

I am looking into your query and will provide a response by next Tuesday (06/10/25). Thank you for your patience.

Best Regards,

Zackary Fleenor

Hey Oleg,

Appologies for the delayed response here. I think this is something that can be done, but it will require somewhat complicated routing.

I am including a diagram below to demonstrate how this might be possible. Please review and let us know if this solution would work for your application. Note the requirment of an additional pin. This type of solution also has a possible timing impact. What is the expected SSI/UART communciation frequencies?

Best Regards,

Zackary Fleenor

Too bad, the initial question was about how to do it without rerouting.

In fact I have 2 cases here:

case 1: I am using the CM core for device communication via UART0 port, as it is why the "Connectivity Manager" exist. But when I need the field firmware update I will need to switch to SCIA port, which is using different pins. And as for TX pin it is easy to route UART TX to same pin as SCIA TX, for RX pin it is a problem.

case 2: I have the board with error in roting, the SSI SOMI port was routed to GPIO15 instead of GPIO 17. The question was if there is any way to patch this in software without rerouting board or making patch wires.

I fact, I wonder what will happend if I point OUTPUTXBAR to the input pin. Of couse, SysConfig will refuse to do it due to "resource conflict", but I used this trick before on MSP430, and Tiva C, and other MCUs. The idea is to configure the port as peripheral input and then change its direction. As in this case the port read will directly reflect port write, I used it to emulate external peripheral without physical connection.

For the cases noted above, the solution using reroting/wiring is even more simple. I just connect (UART RX+SCIA RX) or (GPIO15+GPIO17) together and ensure that unsused pin is tri-stated (which is standart behavior for boot loader). So no crossbar is needed.

Hey Oleg,

Thank you for describing your previous solutions. We're you able to come to a solution for your current use-cases without rerouting?

Best Regards,

Zackary Fleenor

Unfortunally I do not have access to the board now, but I have here F28379D launchpad here. I will try to use 2 different SCI ports to test if this is possible.

No, the C2000 devices is impossible to fool in this way, as the MUX function is exclusive and DIR function applies only to GPIO mode, not peripheral mode.

So sad.