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: 226a3188975b21d29d32fe4423a6c929766192a5). 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 https://github.com/earlephilhower/arduino-pico/blob/226a3188975b21d29d32fe4423a6c929766192a5/cores/rp2040/SoftwareSerial.h#L40-L41 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.