Scanning examples

Basic scan

This example initializes the DE2120 scanner over HardwareSerial (UART2 on ESP32), then continuously polls for barcodes and prints any result to the Serial Monitor.

Open the Serial Monitor at 115200 baud to observe scan results.

#include "HardwareSerial.h"
HardwareSerial scannerSerial(2); // Use UART2

#include "DE2120-SOLDERED.h"
DE2120_Soldered scanner;

#define BUFFER_LEN 40
char scanBuffer[BUFFER_LEN];

void setup()
{
  Serial.begin(115200);
  Serial.println("DE2120 Barcode Scanner");

  scannerSerial.begin(115200, SERIAL_8N1, 4, 5); // RX=GPIO4, TX=GPIO5
  delay(500);

  if (scanner.begin(scannerSerial) == false)
  {
    Serial.println("Scanner did not respond. Check wiring and ensure POR232 barcode was scanned. Freezing...");
    while (1);
  }
  Serial.println("Scanner online!");
}

void loop()
{
  if (scanner.readBarcode(scanBuffer, BUFFER_LEN))
  {
    Serial.print("Code found: ");
    for (int i = 0; i < strlen(scanBuffer); i++)
      Serial.print(scanBuffer[i]);
    Serial.println();
  }
  delay(200);
}

Function reference

scanner.begin(HardwareSerial &serialPort)

Initializes the DE2120 scanner on the specified HardwareSerial port. Automatically negotiates the baud rate down to 9600 bps if needed. Returns false if the scanner does not respond.

Returns value: bool, true if the scanner was detected and initialized successfully

scanner.begin(SoftwareSerial &serialPort)

Initializes the DE2120 scanner on the specified SoftwareSerial port. Automatically negotiates the baud rate. Returns false if the scanner does not respond.

Returns value: bool, true if the scanner was detected and initialized successfully

scanner.readBarcode(char *resultBuffer, uint8_t size)

Checks for incoming barcode data. When a complete barcode string (terminated by a carriage return) is received, it is copied into resultBuffer and the function returns true. Returns false if no complete barcode is available yet.

Returns value: bool, true when a complete barcode has been received

Full example

HardwareScan.ino

Basic barcode scanning example using HardwareSerial (UART2) on ESP32

Configuring the scanner

This example demonstrates how to send configuration commands to the scanner at runtime using sendCommand(). It toggles Code ID — a feature that prepends a symbology identifier character to every decoded barcode (e.g. A for Code 128, Q for QR Code), which is useful when your application needs to distinguish barcode types.

Open the Serial Monitor at 115200 baud and type y to enable Code ID or n to disable it. The scanner will also print any barcodes it reads while waiting for input.

#include "SoftwareSerial.h"
SoftwareSerial softSerial(4, 5); // RX=4, TX=5 — change to match your wiring

#include "DE2120-SOLDERED.h"
DE2120_Soldered scanner;

#define BUFFER_LEN 40
char scanBuffer[BUFFER_LEN];

void setup()
{
  Serial.begin(115200);
  Serial.println("DE2120 Barcode Scanner");

  if (scanner.begin(softSerial) == false)
  {
    Serial.println("Scanner did not respond. Check wiring and ensure POR232 barcode was scanned. Freezing...");
    while (1);
  }
  Serial.println("Scanner online!");
}

void loop()
{
  flushRx();

  Serial.println();
  Serial.println("Transmit Code ID with barcode? (y/n)");

  while (Serial.available() == false)
  {
    if (scanner.readBarcode(scanBuffer, BUFFER_LEN))
    {
      Serial.print("Code found: ");
      for (int i = 0; i < strlen(scanBuffer); i++)
        Serial.print(scanBuffer[i]);
      Serial.println();
    }
    delay(200);
  }

  switch (Serial.read())
  {
    case 'y':
      Serial.println("Code ID enabled");
      scanner.sendCommand("CIDENA", "1");
      break;
    case 'n':
      Serial.println("Code ID disabled");
      scanner.sendCommand("CIDENA", "0");
      break;
    default:
      Serial.println("Command not recognized");
      break;
  }
}

void flushRx()
{
  while (Serial.available())
  {
    Serial.read();
    delay(1);
  }
}

Function reference

scanner.sendCommand(const char cmd, const char arg = "")

Sends a raw configuration command to the scanner. The library automatically wraps the command in the required protocol format (^_^COMMAND<ARG>.). Waits up to 3 seconds for an ACK or NACK response.

Returns value: bool, true if the scanner acknowledged the command (ACK), false on NACK or timeout