Clarification on Pin Connections port mapping for generic configuration

[jattie-ire]

Gents,

thanks for sharing this amazing piece of work, what a gem to be able to turn a Pico into a GRBL controller.

I am referring to this mapping that I have compiled and successfully use on my 2 axis project.
https://github.com/grblHAL/RP2040/blob/master/boards/generic_map.h#L55

I have three questions I cannot figure out myself and hope to get clarified here.

Question one, the generic map reference a port 23, however a Pico 2040 has no port 23, is this a simple error or a misunderstanding on my part?

#define AUXINPUT2_PIN 23

My second question for better understanding to application and configuration options. Why the mapping skips over GPIO 0 and GPIO 1? I assume it is for serial, I2C or SPI, but I do not see options to build for options to exploit that, any hints?

Last question, with the 3 axis config, GPIO 18,19 and 20 are unmapped, and mapped in 4 axis as reset, feed hold and cycle start.

https://github.com/grblHAL/RP2040/blob/master/boards/generic_map_4axis.h#L107

Is there a reason for leaving them out or can they simple be added to the config?

Thanks

[terjeio]

Question one, the generic map reference a port 23, however a Pico 2040 has no port 23, is this a simple error or a misunderstanding on my part?

It is a simple error, 'll remove the definition.

Why the mapping skips over GPIO 0 and GPIO 1? I assume it is for serial, I2C or SPI,

It is for UART serial.

I do not see options to build for options to exploit that, any hints?

I always assign at least one UART serial port. That could be changed by having a code guard that skips stream registration, this since the pins are only configured when an serial port is opened for use. The tricky bit is how to handle pin assignments if functionality that requires a serial port is enabled. At some point it will be, IMO, better to just define a custom map.

Last question, with the 3 axis config, GPIO 18,19 and 20 are unmapped, and mapped in 4 axis as reset, feed hold and cycle start.
https://github.com/grblHAL/RP2040/blob/master/boards/generic_map_4axis.h#L107
Is there a reason for leaving them out or can they simple be added to the config?

The guards (#if ... #else .. #endif blocks) looks ok to me. Have you tried using the map in a 3-axis configuration and they are not there?