sys.imports External references

[Jerry Messina]

Looking through the sources in the Library\sys.imports dir, I see some references in the file SysFirewing.bas such as

Code: Select all

public External sub PPSLock()

I can't find them defined anywhere. What are these, and how does the external linkage work?

[majenko]

They are (I think) in the internal Firewing object.

The PPSLock() and PPSUnlock() functions are used to enable / disable the Peripheral Pin Select functionality of the PIC24 MCU. This is used for remapping peripheral pins to specific physical pins. Locking the PPS system prevents accidental remapping of pins when you don't want it to happen.

[Jerry Messina]

In this case (the PPS functions) I know what they do, but not where they're actually defined.

The others I can only guess at.

[majenko]

That's one for Dave then I'm afraid... I don't know the internals of the Firewing compiler

[David John Barker]

You wont find the function implementations, as they are currently hard coded. Using "external" is not recommended, as the compiler currently has a narrow view of what commands it processes or lets through using "external". This may change in the future, but for now read "external" as compiler specific.