Pin definition in config.txt

In the config.txt configuration file using smoothieware on the C3D board, how are the pins defined?

I see two numbers (separated by a period or dot) for each pin. For example alpha_step_pin = 2.0 and alpha_dir_pin = 0.5. There are 100 pins on the mcu used on this board, 25 pins for each of the 4 sides in a QFP package. Regardless of how I look at it I don’t understand the scheme used to name these pins. I have seen 0, 1, 2, 3, and 4 used for the number preceding the dot and numbers between 0 and 29 used for the number following the dot.

I have another related question regarding the configuration file…an exclamation mark (!) is used as an NOT or inverse operator. I also see a caret (^) used, it doesn’t appear to be used in an OR function…what does ^ denote in the config.txt

Thanks for your time.

Trent - KM4YTU

EDIT 08/27/2020 14:15 : Example for clarification, you can find both the ! and ^ used on line 301 of the default config.txt shipped with V0.2 of smoothieware shipped with the C3D board. "zprobe.probe_pin 1.28!^ "

The pins on the microcontroller are grouped as logical ports that can be written to/read from in parallel in a single instruction cycle - the m.n notation is - so for instance 0.5 corresponds to P0[5]/I2SRX_WS/TD2/CAP2[1] in the datasheet and physical pin 80 on the LQFP100.

The carat character in a pin specification turns on the internal pull-up resistor for the pin in question. ( has all the options you can use here)



Thank you for your prompt and clear reply.
That is exactly what I needed and perfectly answered my question.

Best regards,
Trent - KM4YTU

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