printf does not output anything with the %c format charater

[akoerner]

Problem

printf("%c", 'A'); outputs nothing

Environment

Arduino UNO Windows 10 Arduino IDE 1.18.13 LibPrintf 1.1.3

Expected Behavior

Given the following program compiled and uploaded to the Arduino I would expect the serial console to show a single "A" character

#include <LibPrintf.h>\\LibPrintf 1.1.3

void setup() {
  Serial.begin(9600);
  printf("%c", "A");
}

void loop() {

}

Actual Behavior

nothing outputs to the serial console. Installing LibPrintf Version 1.1.2 results in the correct and expected behavior.

[phillipjohnston]

Huh, versioning must be messed up somewhere, as I'm expecting versions in the 1.2.x range. I'll look into this - I expected the problem to be fixed with this release. https://github.com/embeddedartistry/arduino-printf/releases/tag/1.2.8

What's happening is that GCC is optimizing that printf call to putchar, which is either not implemented or not implemented correctly in avr-libc.

[phillipjohnston]

1.2.6 (latest available in Library Manager) has the issue, I am spinning 1.2.10 with an updated library.properties file which will have the fix.

[akoerner]

1.2.6 (latest available in Library Manager) has the issue, I am spinning 1.2.10 with an updated library.properties file which will have the fix.

1.2.10 is now available via the Library Manager and resolves the issue.