Pass templated function as attachInterrupt parameter

Question

So I want to do something like this:

template<int PIN, int CHANNEL>
void initPin() {
 attachInterrupt(PIN, rising<PIN, CHANNEL>, RISING);
}
template<int PIN, int CHANNEL>
void rising() {
 startTimes[CHANNEL] = micros();
 attachInterrupt(PIN, falling<PIN, CHANNEL>, FALLING);
}
template<int PIN, int CHANNEL>
void falling() {
 values[CHANNEL] = micros() - startTimes[CHANNEL];
 attachInterrupt(PIN, rising<PIN, CHANNEL>, RISING);
}

but the compiler gives me this error

no matches converting function ‘rising’ to type ‘void (*)()’

Can I even do this, or do I have to write all the functions by myself?

Answer 1

Try this:

template<int PIN, int CHANNEL> void initPin() {
 attachInterrupt(PIN, rising<PIN, CHANNEL>, RISING);
}
template<int PIN, int CHANNEL> void rising() {
 startTimes[CHANNEL] = micros();
 attachInterrupt(PIN, falling<PIN, CHANNEL>, FALLING);
}
template<int PIN, int CHANNEL> void falling() {
 values[CHANNEL] = micros() - startTimes[CHANNEL];
 attachInterrupt(PIN, rising<PIN, CHANNEL>, RISING);
}

The problem is actually the Arduino preprocessor. It adds illegal forward declarations if template functions are formated as your original code.

Answer 2

Please have a look implementation https://github.com/Yurik72/SimpleButton

There are implementation how to assign function with arguments to interrupt handler