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RM57L843: :Inputs are broadcast to all multiplexed functions

raheel bari
Intellectual 575 points
Part Number: RM57L843

Hi

With reference to SPNU562 a note on page 295 (IOMM) is written as:

""The input signals are broadcast to all modules hooked up to a terminal. The application must ensure that modules that are not being used in the application do not react to a change on
their input functions. e.g. a GIO signal toggle can trigger an interrupt request, when the application actually is using the function multiplexed with this GIO signal.""

With reference to this note I'm unable to understand the can i use two modules simultaneously. As pin signal is broadcasted to all modules, without a multiplexer. As shown in Fig 6-3. 

So, I'm confused by this statement " The application must ensure that modules that are not being used in the application do not react to a change in their input functions".  

What are the precautions in hardware if any?

Regards;

 

  • 0
    TI__Guru 59540 points

    Raheel,

    Generally speaking, only the output buffers are muxed which is why the inputs will continue to be connected to the secondary IP on the pin. However, we also have some of the pins that have input muxing as well in cases where a function will still be available on another pin (same function is mapped to multiple pins). In this case, you will need to setup both the input and output muxes to select the proper function on all pins involved and insure the input comes from the correct pin location. GIOB[0], if I recall correctly, is a prime example of this.

    In the case where a function is only mapped to a single pin together with a second function via an output mux, if the output is selected to be the secondary function, the default function (first level), is no longer available.

    In regard to your statement:

    Raheel Bari said:
    With reference to this note I'm unable to understand the can i use two modules simultaneously. As pin signal is broadcasted to all modules, without a multiplexer. As shown in Fig 6-3.

    I am not entirely certain what you are asking but will assume you are asking if you can use the IP that is mapped to a pin if the pin is selected as another or separate IP/function. The short answer here is it depends. For example, if the alternate function on a pin is chosen over an SCI Rx, it becomes impossible to use the SCI in a full duplex mode of operation. However, it may still be able to be used in a TX only mode. In short, it comes to understanding the IP and understanding the choices of the functions that are muxed together. In most cases, it won't be an issue and you can simply exclude the function from use and, in other cases, it may alter if or how you can use the IP. If there are explicit examples, we can discuss those to be more specific how to work around them.