New Interrupt Driven Serial Echo Example

[AdinAck]

Motivation

• The provided serial_echo example seemed lacking imho
• Would be really nice if it used interrupts

Change(s)

• Added serial_echo_irq.rs to /examples

[AdinAck]

This compiles and runs on my end... looking into it.

[AdinAck]

that first error makes no sense, still compiles in my deployment repo but not in this repo... 🤷‍♂️

[therealprof]

Adding an example seems fine to me, though this is unnecessarily complex and convoluted:

• The macros (just to deal with the global variables) seem a bit over the top and make it even harder to follow for the uninitiated.
• Since you're toggling the LED in the main loop, there's no need for all that extra global complexity, a local variable will do.

PS: If you want to use a resource only in a single place (like an interrupt handler), you can also move it into a variable in the interrupt handler once and then safely use it without a critical section.

[AdinAck]

• The macros (just to deal with the global variables) seem a bit over the top and make it even harder to follow for the uninitiated.

Yes those were left over from my main project where I have many global variables and want it to be easy to use them later, I will remove this.

• Since you're toggling the LED in the main loop, there's no need for all that extra global complexity, a local variable will do.

Haha another remnant from my main project, I will fix this as well.

PS: If you want to use a resource only in a single place (like an interrupt handler), you can also move it into a variable in the interrupt handler once and then safely use it without a critical section.

I have no idea what this means, and if you are able to explain to me further at your convenience, I would greatly appreciate it.

[AdinAck]

I believe I have correctly converted the example over to the proper way of using the global serial port. I have also rebased this PR.

[AdinAck]

#170 will fix this PR.