wanted to connect this device to Arduino. I want to send data from arduino to this module. I have connected the rx pin on arduino to txd pin on the device and txd pin of device to rxd of arduino . I have connected 5v pin of arduino to 5v pin of this device and ground pin of this device to ground pin of Arduino. It is not working. I am a newbie. Can you guys help me ?
- Voltage Compatibility – Even though you're using 5V power, many modules operate on 3.3V logic levels. The EC200U CN might not handle 5V signals well. Check the specifications of your modem—if it requires 3.3V logic, you may need a logic level shifter to convert signals properly.
- Baud Rate Mismatch – Make sure your Arduino’s serial baud rate matches the modem’s expected baud rate. Try setting it to 115200 (which is common for these modules) or check its datasheet.
- Software Implementation – Are you using
SerialorSoftwareSerialon your Arduino? If you're using an Arduino Uno, its hardware serial (Serial) is linked to the USB interface, so you may need to use SoftwareSerial on other pins (e.g.,rx = 10, tx = 11). - Power Stability – While you've connected the modem to 5V, some modems require more current than the Arduino's 5V regulator can supply. Try using an external 5V power source with enough capacity.
- AT Commands – Have you tried sending basic AT commands to check if the modem responds? Open the serial monitor and send
AT—if the modem is working, it should reply withOK.
there are a number of modules based on the quectel ec200u-cn
can you give a link to the specific module you are using?
not used the EC200 but have used the Quectel EC21
can second @adityasingh76 in stating do not connect 5V logic to the module IOs
also check the logic levels - I know that some of the EC21 signals use 1.8V logic - the EC200 may be similar
check that the power supply is 5V - it may be 3.3V to 4.4V
I would recommend you test using a microcontroller which uses 3.3V logic, e.g.RP2040, ESP32, etc