How to connect a thermal printer to an ESP32? - printing

Question

I want to attach my GOOJPRT Thermal Printer (I believe model QR701, communication RS232) to my ESP32 but I cannot seem to get them working.
I tried all the Adafruit Thermal Printer library examples but get the same error each and every time:
"Error compiling for board ESP32 Dev Module."
I guess the libraries are not meant for the ESP32.
I also tried the "Thermal Printer Library" by Larry Bank (which should be compatible with the ESP32 according to its github docs) but there I cannot figure out how to connect the wires of thermal printer to the ESP32 correctly.
Of course, I do not ask for a specific solution, I am just looking for someone to point me in the right direction!
This is an image of the exact thermal printer I have
Full error message from Adafruit Thermal Printer examples:
C:\Users\Thomas\Documents\Arduino\libraries\SoftwareSerial-master\SoftwareSerial.cpp:41:27: fatal error: avr/interrupt.h: No such file or directory
compilation terminated.
Multiple libraries were found for "Adafruit_Thermal.h"
Used: C:\Users\Thomas\Documents\Arduino\libraries\Adafruit_Thermal_Printer_Library
Not used: C:\Users\Thomas\Documents\Arduino\libraries\Adafruit-Thermal-Printer-Library-master
Multiple libraries were found for "SoftwareSerial.h"
Used: C:\Users\Thomas\Documents\Arduino\libraries\SoftwareSerial-master
Not used: C:\Users\Thomas\Documents\Arduino\libraries\EspSoftwareSerial
exit status 1
Error compiling for board ESP32 Dev Module

Answer 1

You need to use the <HardwareSerial.h> library. SoftwareSerial is for Arduino boards.
"Thermal Printer Library" by Larry Bank is for GOOJPRT PT-210 and use Bluetooth. Won't work for qr-701.
Instead of using Adafruit Library, you can try with this:
ThermalPrinter
Quick start:
Import libraries:
#include "TPrinter.h"
#include <HardwareSerial.h>
Set baudrate and pins.
const int printerBaudrate = 9600; // or 19200 usually
const byte rxPin = 16; // check datasheet of your board
const byte txPin = 17; // check datasheet of your board
const byte dtrPin = 27; // optional
const byte rsePin = 4; // direction of transmission, max3485
You need to use boad with max3485(for 3V3 logic lvl) or similar, if you have printer with rs232.
Necessary in my case. I use board UART - RS485 3,3V - ARK/RJ11 - Waveshare 4777
Init
HardwareSerial mySerial(1);
Tprinter myPrinter(&mySerial, printerBaudrate);
void setup() {
micros();
mySerial.begin(printerBaudrate, SERIAL_8N1, rxPin, txPin); // must be 8N1 mode
pinMode(rsePin, OUTPUT); // optional
digitalWrite(rsePin, HIGH); // optional
// myPrinter.enableDtr(dtrPin, LOW); // optional
myPrinter.begin();
}