Bug (solved): D24 bit value is wrong in digital pin masks.

[rafacouto]

In Leonardo hardware pin assignment, the correspondence between bit mask and pin PD5 is missing, while PD4 is repeated as D24, so D24 should be PD5.

Atmega32U4 PD5 pin is XCK1/~CTS and it is connected to TX led on Leonardo board. After this patch, D24 is assigned to PD5 and these lines can blink TX led:

void setup() {
  pinMode(24, OUTPUT);
}

void loop() {
 digitalWrite(24, HIGH);   // turn the LED on (HIGH is the voltage level)
 delay(500);              // wait for a second
 digitalWrite(24, LOW);    // turn the LED off by making the voltage LOW
 delay(500); 
}

This bug was found by @xdesig (member of the Escornabot project :) This is his hardware unit test: https://www.youtube.com/watch?v=nClBTrmG7Sk

[NicoHood]

That is correct, D4 is A6 so pin 24 is useless and can be assigned to the other LED which is not used yet.

I'd also vote for a
#define LED_BUILTIN_TX 24
#define LED_BUILTIN_RX 17

[NicoHood]

Its such a simple fix, why dont you apply this?

[matthijskooijman]

I don't think this fix is correct. Pin 24 was previously used for (virtual) pin "A6", which is the analog input mode on pin D4. This needs a duplicate pin number to be assigned to pin PD4 (as well as others), because analogRead() is expected to work with both pin numbers and analog channel numbers (e.g. 0 for A0). If you would just say A6 = 4 and then do analogRead(A6), this would cause ambiguity: Did you mean pin 4 (A6) or channel 4 (A4)?

So I believe that D24 must remain unchanged. Adding a pin for the TX led makes sense, though I'm not sure if it would be ok to add it at the end - some code might be assuming that the last NUM_ANALOG_INPUTS are analog pins (though perhaps not). See also #2071, where some similar problems were encountered.

[NicoHood]

Oh you are right. But why not use another pin for the led then?

#define LED_BUILTIN_TX 30
#define LED_BUILTIN_RX 17

[cmaglie]

As stated by @matthijskooijman the current pin assignment is correct.
Closing as invalid.