Sparkfun DE2120 Won't Respond

Other Hardware Sensors
1

I am trying to connect the Sparkfun DE2120 Barcode Scanner to my Arduino MKR WiFi 1010. Whenever I run the code below (which I modified slightly from the example in the library for the module) I only ever get the "Scanner did not respond. Please check wiring. Did you scan the POR232 barcode? Freezing.." message. My wiring is as follows:
Scanner Arduino
GND -> GND
3.3V -> VCC
TX -> 14
RX -> 13

I have confirmed that the scanner works using the USB interface and have made sure to scan the barcode to put it in TTL mode. Can anyone point me in the right direction as to what might be causing the issue?

#include "SparkFun_DE2120_Arduino_Library.h"  //Click here to get the library: http://librarymanager/All#SparkFun_DE2120
DE2120 scanner;

#define BUFFER_LEN 40
char scanBuffer[BUFFER_LEN];

void setup() {
  Serial.begin(115200);
  Serial1.begin(9600);
  Serial.println("DE2120 Scanner Example");

  if (scanner.begin(Serial1) == false) {
    Serial.println("Scanner did not respond. Please check wiring. Did you scan the POR232 barcode? 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);
}

Scheme-it-export-barcode-scanner-2025-06-26-23-36
Scheme-it-export-barcode-scanner-2025-06-26-23-36409×471 33.6 KB

2

Do I understand that the USB cable is plugged into the scanner, and it powers the Arduino?
The problem with that is the Arduino can't print any errors but maybe the wiring diagram will clarify the hookup.

3

Does it show as a device in your system (when plugged in)?

It appears to "work" new-out-of-box, just using USB power, without an mcu, but you must configure it by scanning some of the scan codes provided in the manual (linked from readme.md).

For example, for serial scanning...

NOTE: You must put the module into TTL mode by scanning the POR232. barcode in the datasheet. This will put the module in the correct mode to receive and transmit serial. The baud rate in POR232 defaults to 115200 which is too fast for software serial. This library will automatically set the baud rate to 9600bps.

This is not in the code you posted.

4

I have added a wiring diagram that should make things more clear. The scanner is getting power from the Arduino's 3.3V VCC.

5

It does show up as a device in my system when plugged directly into my laptop. I have scanned the POR232 barcode and have also tried scanning the one to set it to 9600 baud. I still get no response

6

Is sufficient power applied to the device? Maybe the device draws more than the MKR can supply. Do you have an external power supply at the correct voltage?