# Arduino Uno and Quectel EC25

**URL:** <https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548>\
**Category:** Networking, Protocols, and Devices\
**Created:** [January 8, 2024, 1:58pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548 "2024-01-08T13:58:06Z")\
**Posts on this page:** 17\
**Page:** 1

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**Author:** ![ryzenxirus](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ryzenxirus/32/975773_2.png) [@ryzenxirus](https://forum.arduino.cc/u/ryzenxirus)\
**Post date:** [January 8, 2024, 1:58pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/1 "2024-01-08T13:58:06Z")

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hello everyone, i would like to know if anyone has connected the EC25 module to an arduino. i am trying but i cannot communicate with the serial.

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<div class="post-metadata">

**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\
**Post date:** [January 8, 2024, 2:41pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/2 "2024-01-08T14:41:22Z")

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have a read thru [how-to-get-the-best-out-of-this-forum](https://forum.arduino.cc/t/how-to-get-the-best-out-of-this-forum/679966)  
in particular  
1.which microcontroller are you planning to use  
2. give details of the EC25 module? give a link? or a photo?  
3. post your code - select \< CODE/ \> and paste the code or text where it says “type or paste code here”

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<div class="post-metadata">

**Author:** ![ryzenxirus](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ryzenxirus/32/975773_2.png) [@ryzenxirus](https://forum.arduino.cc/u/ryzenxirus)\
**Post date:** [January 8, 2024, 3:01pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/3 "2024-01-08T15:01:59Z")

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Sorry, i'm new on this forum.

I use Arduino UNO R2  
This is the module: [https://www.quectel.com/product/lte-ec25-series](https://www.quectel.com/product/lte-ec25-series)  
This is my code:

```arduino
#include <SoftwareSerial.h>

//Create software serial object to communicate with SIM800L
SoftwareSerial mySerial(4,5); //SIM800L Tx & Rx is connected to Arduino #3 & #2

void setup()
{
  //Begin serial communication with Arduino and Arduino IDE (Serial Monitor)
  Serial.begin(9600);
  
  //Begin serial communication with Arduino and SIM800L
  mySerial.begin(115200);

  Serial.println("Initializing...");
  delay(1000);

  
}

void loop()
{
  mySerial.println("AT"); //Once the handshake test is successful, it will back to OK
  Serial.println("AT");
  updateSerial();
  mySerial.println("AT+CSQ"); //Signal quality test, value range is 0-31 , 31 is the best
  Serial.println("AT+CSQ");
  updateSerial();
  mySerial.println("AT+CCID"); //Read SIM information to confirm whether the SIM is plugged
  Serial.println("AT+CCID");
  updateSerial();
  mySerial.println("AT+CREG?"); //Check whether it has registered in the network
  Serial.println("AT+CREG?");
  updateSerial();

  delay(2000);
}

void updateSerial()
{
  delay(1000);
  while (Serial.available()) 
  {
    mySerial.write(Serial.read());//Forward what Serial received to Software Serial Port
  }
  Serial.println(mySerial.available());
  while(mySerial.available()) 
  {
    Serial.write(mySerial.read());//Forward what Software Serial received to Serial Port
  }
}

```

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<div class="post-metadata">

**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\
**Post date:** [January 8, 2024, 3:09pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/4 "2024-01-08T15:09:00Z")

</div>

a couple of things

1. run Serial at the same or a high baud rate than any other serial ports or you may overrun the buffers
2. SoftwareSerial will not run a 115200baud on a UNO - the fastest is about 38400baud

upload a schematic showing how you have connected the EC25 to the UNO

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<div class="post-metadata">

**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\
**Post date:** [January 8, 2024, 4:17pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/5 "2024-01-08T16:17:45Z")

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I have a number of Quectel modems but are in the main on custom PCBs  
the exception is a [Quectel Mini PCIe EVB Kit](https://www.quectel.com/product/mini-pcie-evb-kit) fitted with a EC21 evaluation module

using an ESP32 with a RS232-TTL module I cross connected 9-pin D-type connector pins 2 and 3 to the RS232 9-pin D-type connector on the kit, e.g.

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/1/c/b/1cb875bee853ea8b7963087758571797483d692f.jpeg)

ran the following code

```cpp
// ESP32 Serial1 test - for loopback test connect pins 16 and 17

#define RXD1 16
#define TXD1 17

void setup() {
  // initialize both serial ports:
  Serial.begin(115200);
  //Serial1.begin(115200, SERIAL_8N1, RXD1, TXD1);
  Serial1.begin(115200, SERIAL_8N1, RXD1, TXD1);
  Serial.println();
  Serial.println("\n\nESP32 serial1 test Rx pin 16 Tx pin 17");
  Serial.write(" for loopback test connect pin 16 to pin 17\n");
}

void loop() {
  // read from port 1, send to port 0:
  if (Serial1.available()) {
    int inByte = Serial1.read();
    Serial.write(inByte);
  }

  // read from port 0, send to port 1:
  if (Serial.available()) {
    int inByte = Serial.read();
    //Serial.write(inByte);
    Serial1.write(inByte);
  }
}

```

typing AT commands on the serial monitor I get response

```arduino
ESP32 serial1 test Rx pin 16 Tx pin 17
   for loopback test connect pin 16 to pin 17
at
OK
at+cgmi
Quectel
OK
at+cgmr
EC21EFAR06A06M4G
OK
at+cgmm
EC21
OK
at+csq
+CSQ: 15,99
OK
at+cimi
+CME ERROR: 3

```

I get an error to AT+CIMI (returns IMSI of the SIM card) becuase I don't have a SIM card in the holder

how is your EC25 connected to the UNO and how is it powered?

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<div class="post-metadata">

**Author:** ![ryzenxirus](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ryzenxirus/32/975773_2.png) [@ryzenxirus](https://forum.arduino.cc/u/ryzenxirus)\
**Post date:** [January 9, 2024, 9:39am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/6 "2024-01-09T09:39:16Z")

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hi, i change my MCU, now i use ESP32 S3.

i have a lot of minipcie of quectel ec25 and a usb minipcie.

 ![Ec25 + USB Minipcie](https://europe1.discourse-cdn.com/arduino/original/4X/9/6/0/96086f2f5c9cc2ad2cdccaca278fd9620293aa7e.jpeg)

I connected it to CH340G (USB2TTL).

Now i connected it to ESP32 S3 to pin 16 and pin 17

 ![Ec25 + USB Minipcie + CH340G + ESP32 S3](https://europe1.discourse-cdn.com/arduino/original/4X/3/c/9/3c990f9e11688fcb4e55fd0b1eb53842e40bf2fe.jpeg)

This is the pinout of ESP32 S3:

 ![pinout of ESP32 S3](https://europe1.discourse-cdn.com/arduino/original/4X/f/9/1/f913ef1079478554bf0fd295c9ba14a53b206b6f.jpeg)

i try also to connect to pin 17 and 18 but it not work.

Do you have some suggestions ?

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<div class="post-metadata">

**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\
**Post date:** [January 9, 2024, 9:55am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/7 "2024-01-09T09:55:28Z")

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have you a specification of the USB-TTL module? or a link to it?  
is it TTL output 5V logic or 3.3V logic?  
the ESP32-S3-DevKitC-1 is 3.3V logic so if the USB-TTL uses 5V logic you will require a potential divider on the USB-TTL Tx to ESP32-S3 Rx

are you sure you have connected to ESP32-S3-DevKitC-1 GPIO17 and GPIO18  
the pinout diagram and you photo don't appear to correspond - I think you may be connected to GPIO15 and GPIO16

I also don't see a GND connection between the USB-TTL and ESP32-S3

the following works on my ESP32-S3-DevKitC-1 using pins 18 and 17

```cpp
// ESP32-S3 DevkitC-1 Serial1 test - for loopback test connect pin GPIO17 U1TXD to pin GPIO18 U1RXD"
// ss https://docs.espressif.com/projects/esp-idf/en/latest/esp32s3/_images/ESP32-S3_DevKitC-1_pinlayout_v1.1.jpg

#define RXD1 18
#define TXD1 17

void setup() {
  // initialize both serial ports:
  Serial.begin(115200);
  Serial1.begin(115200, SERIAL_8N1, RXD1, TXD1);
  Serial.println();
  Serial.println("\n\nESP32-S3 DevkitC-1 serial1 test pin GPIO17 U1TXD pin GPIO18 U1RXD");
  Serial.write(" for loopback test connect pin GPIO17 U1TXD to pin GPIO18 U1RXD\n");
}

void loop() {
  // read from port 1, send to port 0:
  if (Serial1.available()) {
    int inByte = Serial1.read();
    Serial.write(inByte);
  }

  // read from port 0, send to port 1:
  if (Serial.available()) {
    int inByte = Serial.read();
    //Serial.write(inByte);
    Serial1.write(inByte);
  }
}

```

if you connect pins 18 and 17 you can do a loopback test  
characters entered on the serial monitor should echo back and be displayed  
it at least proves the serial port works and you have the correct pins

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<div class="post-metadata">

**Author:** ![ryzenxirus](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ryzenxirus/32/975773_2.png) [@ryzenxirus](https://forum.arduino.cc/u/ryzenxirus)\
**Post date:** [January 9, 2024, 10:25am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/8 "2024-01-09T10:25:28Z")

</div>

my USB2TTL module is this: [https://www.amazon.fr/AZDelivery-Adaptateur-convertisseur-capteur-Raspberry/dp/B07N7MC999](https://www.amazon.fr/AZDelivery-Adaptateur-convertisseur-capteur-Raspberry/dp/B07N7MC999)

i think it is to 5v logic.

I check all wires, i think all is ok.

With pin 17 and 18 i cannot send command with Serial Monitor.

 ![Wire to ESP32 S3](https://europe1.discourse-cdn.com/arduino/original/4X/1/5/8/15866b7b243bb1ca81dd79b3acd59397197d5a95.jpeg)

i send a lot of AT but i don't see nothing:

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/3/d/0/3d0c57708153849599d847f0b9330b9a730542cb.png)

I think there is a problem with the Serial1.

I can use it with a softwareSerial ?

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<div class="post-metadata">

**Author:** ![ryzenxirus](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ryzenxirus/32/975773_2.png) [@ryzenxirus](https://forum.arduino.cc/u/ryzenxirus)\
**Post date:** [January 9, 2024, 10:28am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/9 "2024-01-09T10:28:10Z")

</div>

If i use the loopback test on pin 16 an 17 it work.

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/a/8/b/a8bea787b80781596dd07ca3c5c080bc679e8767.png)

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<div class="post-metadata">

**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\
**Post date:** [January 9, 2024, 10:34am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/10 "2024-01-09T10:34:47Z")

</div>

try connecting the USB-TTL to 3.3V rather than 5V  
then connect  
USB-TTL Tx to ESP32-S3 GPIO17  
USB-TTL Rx to ESP32-S3 GPIO16

avoid posting images of screen shots they waste a lot of disk space and cannot be copied from - copy and paste the text using code tags \</\>

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<div class="post-metadata">

**Author:** ![ryzenxirus](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ryzenxirus/32/975773_2.png) [@ryzenxirus](https://forum.arduino.cc/u/ryzenxirus)\
**Post date:** [January 9, 2024, 10:35am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/11 "2024-01-09T10:35:12Z")

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i try also with a ESP32 WROOM 32 but i cannot send the AT Command in Serial monitor

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/e/a/e/eae8961a948c42c9115dcc219b99b52bb3f6bf8d.jpeg)  
 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/e/7/6/e76f6d1302ece5b6c448c7f7276b842d2dbbef06.png)

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<div class="post-metadata">

**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\
**Post date:** [January 9, 2024, 10:47am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/12 "2024-01-09T10:47:07Z")

</div>

does the ES25 module show any sign of life, e.g. LEDs lit?  
can you give a link to the mother board which has the EC25 attached?

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<div class="post-metadata">

**Author:** ![ryzenxirus](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ryzenxirus/32/975773_2.png) [@ryzenxirus](https://forum.arduino.cc/u/ryzenxirus)\
**Post date:** [January 9, 2024, 11:03am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/13 "2024-01-09T11:03:43Z")

</div>

yes the EC25 work because if i connected it to PC i can send it command qith QNavigator

the motherboard of EC25 is the same of this: [Mini Pci-e To Usb With Sim Card Wwan Adapter Card 3g/4g Module | Fruugo IT](https://www.fruugo.it/mini-pci-e-a-usb-con-scheda-sim-wwan-adattatore-scheda-3g-4g-modulo/p-198602359-423108431?language=it&ac=bing&msclkid=425d2162ac701e93d8d144ff8b9bc094&utm_source=bing&utm_medium=cpc&utm_campaign=All_IT&utm_term=4574999167107707&utm_content=IT)

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<div class="post-metadata">

**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\
**Post date:** [January 9, 2024, 11:34am UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/14 "2024-01-09T11:34:00Z")

</div>

maybe worth putting the question on the [Quectel forum](https://forums.quectel.com/)

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<div class="post-metadata">

**Author:** ![ryzenxirus](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ryzenxirus/32/975773_2.png) [@ryzenxirus](https://forum.arduino.cc/u/ryzenxirus)\
**Post date:** [January 9, 2024, 3:04pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/15 "2024-01-09T15:04:46Z")

</div>

hi @horace , when i connect the module to my PC, it create 3 port COM. One for AT COMMAND, One for NMEA and another. how did you choose the AT command port?

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<div class="post-metadata">

**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\
**Post date:** [January 9, 2024, 5:04pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/16 "2024-01-09T17:04:34Z")

</div>

the Quectel Mini PCIe EVB kit I described in post 5 provides the AT serial port on the 9pin D-type connector - no configuration required

The Mini Pci-e To Usb module you are using appears to present a number of USB CDC device interfaces which on Windows requires a device driver to create the various COM ports

I looks like simply connecting a USB-TTL module to it won't work  
you may have to connect it to a USB Host port on a microcontroller such as the ESP32-S3-DevKitC-1 and implement CDC drivers to create the AT command serial port - not a trivial task!

worth asking on the Quectel forum if there is a simple way to connect your EC25 module to a microcontroller such as the ESP32-S3

you could get a Quectel Mini PCIe EVB kit and RS232-TTL module like I used in post 5 - however, the Quectel Mini PCIe EVB kit cost about £120 in the UK

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<div class="post-metadata">

**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\
**Post date:** [July 7, 2024, 5:05pm UTC](https://forum.arduino.cc/t/arduino-uno-and-quectel-ec25/1208548/17 "2024-07-07T17:05:22Z")

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Closed on July 7, 2024, 5:05pm UTC

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