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Experimentalist
12-17-2012, 11:31 PM
Paul

I am trying to understand the significance of the grey on colour notation on the pinout diagram, for example TX1 and RX1 circled on the attached diagram. Each case of grey on colour shows duplicated pins so I assume this is an alternative way to connect to the same pins as in the black on colour notation?

Can you explain?

Thanks
Ex.

el_supremo
12-18-2012, 12:33 AM
The ARM Cortex M4 has a signal multiplexer which allows some pins to be reassigned to a different function. For example, although TX1 is shown as being on pin1, it can be reassigned through software to pin5.
See: http://forum.pjrc.com/threads/431-Reassigning-a-pin-%28SPI-SCK%29?highlight=reassign
and http://forum.pjrc.com/threads/889-T3-Multiple-SPI?highlight=reassign

Pete

PaulStoffregen
12-18-2012, 01:25 AM
Yes, that's correct.

Currently the Serial, Wire and SPI library do not have functions to switch to these other pins. Of course, you can use them if you write directly to the pin configuration registers.

I'm still debating what the function should be. Maybe setPin(pin, function); Or perhaps setPinTX(pin), setPinRX(pin), etc?

Experimentalist
12-18-2012, 09:13 PM
Thanks for the replies. Paul, with regard to your question at first glance the second format seems to have less room for error and seems a little more intuitive.

The main reason I asked was to move the SPI SCK from pin 13 and free the LED for other uses