thermal printer with MKR1000?

I'm trying to get the thermal printer to work on MKR1000. I'm following this tutorial: Issue Printer - Arduino Project Hub. The printer prints the test page (with 9600 baud), I can't print from my Arduino code.

It seems the SoftwareSerial.h is not supported yet on the MKR1000 (header file not found) so I connected the printer RX to pin 14/TX on the MKR (and printer TX to MKR RX/13).

I'm using the following code to test the printer (adapted from A_printertest example from the Adafruit Thermal Printer Library), but it's not printing anything.

I connected an LED to pin 14 and it's flashing when the example program runs ...

Any suggestions on what to try?


Adafruit_Thermal printer(&Serial1);      // Or Serial2, Serial3, etc.

void setup() {
  pinMode(7, OUTPUT); digitalWrite(7, LOW);
  Serial1.begin(9600); // Use this instead if using hardware serial
  printer.begin();        // Init printer (same regardless of serial type)
  printer.println(F("Inverse ON"));

Are the Rx/Tx signal levels the same for both devices?
Did you connect Gnd as well?
Perhaps you miss something like printer.end()?

Ha! I did not connect the ground from the printer to the ground on the MKR1000. I was powering it from USB so that was not obvious to me. It’s printing now! Thanks!