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Is it true that serial port setting is a priority than I/O port setting?

Latest Updated:12/01/2011

Question:

I have been using the 78K/0 until now.
In the 78K/0, complicated settings such as P2 and PM2 were required for serial port I/O.
The P2 I/O port settings influence the serial port operation.
The 78K/4 User's Manual (Document No. U13570) does not include a description of I/O port settings related to serial port settings.
I interpret this to signify that serial port settings are a higher priority than I/O port settings. Is this interpretation correct?

Answer:

No, it isn't.
If you refer to the block diagram of the ports with alternate functions, you can see that PM2 and P2 settings are required.
Concretely, 0 must be written to the P2 output latch corresponding to the pins used serially, 1 must be written to PM2 for the pins used as input serially, and PM2 must be set to 0 for pins used as output.
Suitable Products
78K Family