CE set LOW twice consecutively in startConstantCarrier()

[2bndy5]

RF24/RF24.cpp

Lines 1996 to 1997 in 81348ad

	ce(LOW);
	reUseTX();

where the definition of reUseTX() is

RF24/RF24.cpp

Lines 1325 to 1331 in 81348ad

	void RF24::reUseTX()
	{
	write_register(NRF_STATUS, _BV(MAX_RT)); //Clear max retry flag
	write_register(REUSE_TX_PL, RF24_NOP, true);
	ce(LOW); //Re-Transfer packet
	ce(HIGH);
	}

I think the problem is that reUseTX() doesn't deactivate the CE pin before it needs to clear the MAX_RT flag. It would make sense to me if the radio is put into standby mode before clearing the MAX_RT flag.

Git blame seems a bit confusing. The consecutive ce() calls were added in 77b1e2c, but it was closer to what I would expect beforehand in d0ec0c4 (except without clearing the MAX_RT flag)

I think this was a copy-n-paste oversight, but the changes are 10 years old 😆. FWIW, the CirPy lib does ce(LOW) -> clear flag -> ce(HIGH) as well.

Propsal

in startConstantCarrier():

- ce(LOW); 
  reUseTX();

then in reUseTX():

+     ce(LOW); //Re-Transfer packet 
      write_register(NRF_STATUS, _BV(MAX_RT)); //Clear max retry flag 
      write_register(REUSE_TX_PL, RF24_NOP, true); 
-     ce(LOW); //Re-Transfer packet 
      ce(HIGH); 

---

PS - I found this when writing unit tests to ensure expected behavior in pure rust. 😉

[TMRh20]

Hmm, interesting find! I think you are probably correct in the required order of operations here.

Your rust project seems a bit ambitious, I don't know much rust, but will follow along with interest!