SoftwareSerial does not work anymore in 4.0.1

[jaszczurtd]

As mentioned in the description, my code works without any issues up to version 3.9.5.
Platform: RP2040-Plus

I also tested whether adding "true" to the object constructor would make a difference, but unfortunately, it didn’t.

I noticed some upcoming changes related to RX/TX inversion (commit ID: 226a318). Perhaps you could take another look at the issue with this change in mind?

Please let me know if you need any further information.

[...]

#define SERIAL_RX_GPIO 22
#define SERIAL_TX_GPIO 21

static SoftwareSerial gpsSerial(SERIAL_RX_GPIO, SERIAL_TX_GPIO); <-- inserting "true" here does not change anything for 4.0.1
static TinyGPSPlus gps;

void serialTalks(void);

static bool isGPSInitialized = false;
void initGPS(void) {
  if(!isGPSInitialized) {
    attachInterrupt(SERIAL_RX_GPIO, serialTalks, FALLING);  
    gpsSerial.begin(9600, SERIAL_7N1);
    isGPSInitialized = true;
  }
}

void serialTalks(void) {
  if(gpsSerial.available() > 0) {
    gps.encode(gpsSerial.read());
  }
}

[earlephilhower]

Looks like a typo. If you're using the git version, can you edit

arduino-pico/cores/rp2040/SoftwareSerial.h

Lines 40 to 41 in 226a318

	setInvertTX(invert);
	setInvertRX(invert);

to the following and try (note the underscore in the name):

 setInvertTX(_invert); 
 setInvertRX(_invert); 

And make sure you have the invert flag set in the constructor, of course.

[earlephilhower]

Actually, it was a little more complicated. Please try #2423 and report back. The TX inversion got overwritten by the PIO TX setup before. I've verified normal and inverted on a logic analyzer just now with this new patch.

[gandy92]

Maybe off-topic, but I'm using setInvertTX() in code that also needs to compile with the vanilla rp2040 core (in which case it is acceptable for inverting not being possible). Is there any macro that allows to know if setInvertTX() is available?

[earlephilhower]

You can check the core of this or official using https://github.com/earlephilhower/arduino-pico/blob/master/docs/contrib.rst#compiler-defines-for-porting