SIM5320 3G WCDMA/HSDPA Module
The SIM5320 is a versatile 3G WCDMA/HSDPA module that provides reliable communication capabilities for various applications. Its compact design, high-speed data connectivity, and multiple interfaces make it an ideal choice for projects requiring cellular and GPS functionalities.

On this page
SIM5320 pinout
The SIM5320 pinout includes power, UART communication, control, status indication, antenna connections for WCDMA/GSM and GPS, and SIM card interface pins.
| Pin | Type | Description | Notes |
|---|---|---|---|
| VBAT | Power | Power supply input (3.3V to 4.2V) | Requires stable power supply with peak current up to 2A |
| GND | Ground | Ground connection | Connect to common ground |
| TXD | UART TX | UART Transmit Data (connects to microcontroller RX) | Default baud rate: 115200 bps |
| RXD | UART RX | UART Receive Data (connects to microcontroller TX) | Default baud rate: 115200 bps |
| PWRKEY | Control | Power on/off control (active low) | Pull low for at least 1 second to power on |
| NETLIGHT | Status | Network status indication | LED indicator for network registration status |
| STATUS | Status | Module operating status indication | Shows module power state |
| ANT_MAIN | Antenna | Main antenna connection for WCDMA/GSM | Requires external 3G/GSM antenna |
| ANT_GPS | Antenna | Antenna connection for GPS | Requires external GPS antenna for location services |
3G HSDPA/WCDMA module with downlink speeds up to 3.6 Mbps
Quad-band GSM compatibility: 850/900/1800/1900MHz
Integrated GPS functionality with dedicated antenna connection
Requires SIM card for cellular connectivity
Power consumption: 2A peak during transmission
Default baud rate: 115200 bps (configurable via AT commands)
Wiring the SIM5320 to ESP32
Connect the SIM5320 to your ESP32 via UART for AT command communication. The module requires a stable 3.3V-4.2V power supply with sufficient current capacity (peak 2A). External antennas are required for WCDMA/GSM and GPS functionality.
| SIM5320 pin | ESP32 pin | Purpose |
|---|---|---|
| VBAT | 3.3V-4.2V Power Supply | Provide stable power (NOT from ESP32 pin) |
| GND | GND | Common ground connection |
| TXD | GPIO16 (RX2) | SIM5320 TX to ESP32 RX |
| RXD | GPIO17 (TX2) | SIM5320 RX to ESP32 TX |
| PWRKEY | GPIO4 | Power control (pull low to power on) · optional |
| ANT_MAIN | External 3G/GSM Antenna | Connect WCDMA/GSM antenna |
| ANT_GPS | External GPS Antenna | Connect GPS antenna (optional) · optional |
CRITICAL: Use a dedicated power supply (3.3V-4.2V, 2A peak) - DO NOT power from ESP32 pin!
Default UART baud rate is 115200 bps
Use logic level shifters if ESP32 operates at 5V (though ESP32 is 3.3V)
External 3G/GSM antenna is mandatory for network connectivity
GPS antenna is optional but required for location services
Pull PWRKEY low for at least 1 second to power on the module
Monitor NETLIGHT pin for network registration status
Insert active SIM card before powering on
Ensure good antenna placement for optimal signal reception
SIM5320 code examples
SIM5320 Arduino example
Copy// SIM5320 on ESP32 UART2: module TXD -> GPIO16 (RX2), RXD -> GPIO17 (TX2), PWRKEY -> GPIO4
#define PWRKEY_PIN 4
#define MODEM_BAUD 115200
HardwareSerial modem(2); // UART2
void powerOnModem() {
pinMode(PWRKEY_PIN, OUTPUT);
digitalWrite(PWRKEY_PIN, LOW);
delay(1200); // Hold PWRKEY low to power the module on
digitalWrite(PWRKEY_PIN, HIGH);
delay(5000); // Give the module time to boot and register
}
void sendATCommand(const char *command) {
modem.println(command);
delay(500);
while (modem.available()) {
Serial.write(modem.read());
}
}
void setup() {
Serial.begin(115200);
modem.begin(MODEM_BAUD, SERIAL_8N1, 16, 17); // RX=GPIO16, TX=GPIO17
powerOnModem();
Serial.println("Testing AT communication...");
sendATCommand("AT"); // Should answer OK
sendATCommand("ATI"); // Module identification
sendATCommand("AT+CSQ"); // Signal quality
sendATCommand("AT+CREG?"); // Network registration status
}
void loop() {
// Bridge the Serial Monitor and the modem so you can type AT commands directly
while (Serial.available()) modem.write(Serial.read());
while (modem.available()) Serial.write(modem.read());
}This sketch talks to the SIM5320 over the ESP32's second hardware UART (UART2, RX on GPIO16, TX on GPIO17) - the ESP32 has three hardware UARTs, so the AVR-style SoftwareSerial library is neither available nor needed. GPIO4 pulses the module's PWRKEY to power it on, then a few basic AT commands verify communication, signal quality and network registration. The loop bridges the Serial Monitor to the module so you can type further AT commands interactively. Power the module from a supply that can deliver its transmit-burst current - not from the ESP32's 3.3V regulator.
SIM5320 ESP-IDF example
Copy#include <stdio.h>
#include <string.h>
#include "driver/uart.h"
#include "driver/gpio.h"
#include "freertos/task.h"
#define TX_PIN 17
#define RX_PIN 16
#define PWRKEY_PIN 4
#define UART_PORT UART_NUM_1
void init_uart() {
uart_config_t uart_config = {
.baud_rate = 115200,
.data_bits = UART_DATA_8_BITS,
.parity = UART_PARITY_DISABLE,
.stop_bits = UART_STOP_BITS_1,
.flow_ctrl = UART_HW_FLOWCTRL_DISABLE
};
uart_param_config(UART_PORT, &uart_config);
uart_set_pin(UART_PORT, TX_PIN, RX_PIN, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
uart_driver_install(UART_PORT, 1024, 0, 0, NULL, 0);
}
void power_on_sim5320() {
gpio_set_direction(PWRKEY_PIN, GPIO_MODE_OUTPUT);
gpio_set_level(PWRKEY_PIN, 0);
vTaskDelay(1000 / portTICK_PERIOD_MS); // Hold PWRKEY low for 1 second
gpio_set_level(PWRKEY_PIN, 1);
vTaskDelay(5000 / portTICK_PERIOD_MS); // Wait for the module to initialize
}
void app_main(void) {
init_uart();
power_on_sim5320();
char *test_cmd = "AT\r\n";
uart_write_bytes(UART_PORT, test_cmd, strlen(test_cmd));
while (true) {
char data[128];
int len = uart_read_bytes(UART_PORT, data, sizeof(data), 100 / portTICK_PERIOD_MS);
if (len > 0) {
data[len] = '\0';
printf("Response: %s\n", data);
}
vTaskDelay(1000 / portTICK_PERIOD_MS);
}
}This ESP-IDF example initializes UART communication with the SIM5320 module and powers it on using the PWRKEY pin (GPIO4). The UART interface is configured with GPIO17 as TX and GPIO16 as RX. An AT command is sent to test communication, and responses from the module are printed to the console. The code can be extended to include SMS sending, GPS data retrieval, or establishing internet connectivity via HSDPA.
SIM5320 ESPHome example
Copyuart:
tx_pin: GPIO17 # module RXD
rx_pin: GPIO16 # module TXD
baud_rate: 115200
# ESPHome's sim800l component speaks the generic SIM AT command set, which these modules share for SMS
sim800l:
on_sms_received:
- logger.log:
format: "Received '%s' from %s"
args: [ 'message.c_str()', 'sender.c_str()' ]ESPHome has no dedicated LTE-modem component, and the custom platform older examples used was removed in 2025. The sim800l component speaks the generic SIM AT command set for SMS, which the SIM5320 shares - wire UART2 as shown (115200 baud) and you get on_sms_received plus sim800l.send_sms actions. Data connectivity (LTE networking) is outside ESPHome's scope.
SIM5320 PlatformIO example
Copy[env:sim5320]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200#include <HardwareSerial.h>
#include <Arduino.h>
HardwareSerial sim5320(1);
#define PWRKEY 4
void power_on_sim5320() {
pinMode(PWRKEY, OUTPUT);
digitalWrite(PWRKEY, LOW);
delay(1000); // Hold PWRKEY low for 1 second
digitalWrite(PWRKEY, HIGH);
delay(5000); // Wait for initialization
}
void setup() {
Serial.begin(115200);
sim5320.begin(9600, SERIAL_8N1, 16, 17); // RX, TX
power_on_sim5320();
// Test AT command
sim5320.println("AT");
delay(1000);
while (sim5320.available()) {
Serial.write(sim5320.read());
}
// Send SMS
sim5320.println("AT+CMGF=1"); // Set SMS to text mode
delay(1000);
sim5320.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's number
delay(1000);
sim5320.print("Hello from SIM5320");
sim5320.write(26); // CTRL+Z to send SMS
delay(5000);
}
void loop() {
// Handle incoming data or other functionalities
}This PlatformIO code interfaces with the SIM5320 module using HardwareSerial on an ESP32. The power_on_sim5320 function toggles the PWRKEY pin (GPIO4) to activate the module. The AT command is sent to test communication, and SMS functionality is implemented in the setup. Additional functionalities, like GPS data retrieval or HSDPA internet connectivity, can be added in the loop.
SIM5320 MicroPython example
Copyfrom machine import UART, Pin
import time
# Initialize UART
uart = UART(2, baudrate=9600, tx=17, rx=16)
pwrkey = Pin(4, Pin.OUT)
def power_on_sim5320():
pwrkey.value(0)
time.sleep(1) # Hold PWRKEY low for 1 second
pwrkey.value(1)
time.sleep(5) # Wait for module to initialize
def send_at(command):
uart.write(command + '\r\n')
time.sleep(1)
while uart.any():
print(uart.read().decode('utf-8'), end='')
# Power on the module
power_on_sim5320()
# Test communication
send_at('AT')
# Send SMS
send_at('AT+CMGF=1') # Set SMS to text mode
send_at('AT+CMGS="+1234567890"') # Replace with recipient's number
uart.write("Hello from MicroPython" + chr(26))This MicroPython code communicates with the SIM5320 module over UART. The power_on_sim5320 function activates the module using the PWRKEY pin (GPIO4). The send_at function sends AT commands and prints the responses. The script initializes the module, tests communication, and demonstrates how to send an SMS. Additional logic for handling GPS or internet connectivity can be added.
SIM5320 specifications
About the SIM5320
The SIM5320 is a 3G module: dual-band HSDPA/WCDMA (up to 3.6 Mbps downlink) backed by quad-band GSM/GPRS/EDGE as a fallback, plus a genuinely useful extra - a built-in GPS receiver that shares the same UART and AT command interface as the cellular radio, so a single serial connection gets both connectivity and position.
The problem is timing: as of 2026, 3G/UMTS - the network this module’s headline radio depends on - has already been switched off across most of its practical markets. All three major US carriers finished their 3G shutdown by the end of 2022; Australia’s three carriers completed theirs by late 2024; and most of Western Europe has followed the same path (Germany’s operators cut 3G back in 2021, and the UK’s EE and Vodafone did the same in early 2024). Buying a SIM5320 today for cellular data in any of those regions means the WCDMA radio has nothing left to connect to. What still works regardless: the GPS receiver, which doesn’t care about carrier decisions, and the GSM/GPRS fallback for SMS or low-rate data in the shrinking list of places that still run 2G.
For a new design in 2026, the honest recommendation is an LTE module instead: SIM7600G for genuine broadband-class speed, or SIM7000 if the project only needs occasional low-bandwidth data and wants better battery life. The SIM5320 only makes sense now to reproduce an existing design built around it, to source SMS/GPRS-only connectivity in a market where 2G is still alive, or to use it purely as a GPS module.
SIM5320 troubleshooting
Module Fails to Power On
›
Issue: The SIM5320 module does not power up or respond to commands.
Possible causes include insufficient power supply, incorrect wiring, or faulty hardware.
Solution: Ensure the module is connected to a stable power source within the recommended voltage range of 3.4V to 4.2V. Verify that all connections are secure and correctly configured. If the problem persists, consider testing the module with a different power source or replacing it.
SIM Card Not Recognized
›
Issue: The module fails to detect or register the SIM card.
Possible causes include improper SIM card insertion, unsupported SIM card type, or SIM card lock.
Solution: Ensure the SIM card is properly inserted into the module's SIM card slot and is compatible with the GSM network. Verify that the SIM card is active and unlocked. If necessary, test the SIM card in another device to confirm its functionality.
Poor Network Signal or Connectivity Issues
›
Issue: The module experiences weak signal strength or fails to maintain a stable network connection.
Possible causes include improper antenna connection, environmental interference, or network coverage limitations.
Solution: Ensure the GSM antenna is securely connected to the module and positioned for optimal signal reception. Avoid placing the module near sources of electromagnetic interference. Check the network coverage in your area to ensure adequate signal strength.
AT Commands Not Responding
›
Issue: The module does not respond to AT commands sent from the microcontroller or computer.
Possible causes include incorrect baud rate settings, faulty serial connections, or improper command syntax.
Solution: Verify that the baud rate of the module matches that of the microcontroller or computer; the default baud rate is 115200 bps. Check that the TX and RX lines are correctly connected and that there are no loose connections. Ensure that AT commands are correctly formatted and terminated with a carriage return.
GPS Functionality Not Working
›
Issue: The SIM5320 module fails to acquire GPS signals or provide location data.
Possible causes include improper antenna connection, obstructed view of the sky, or GPS functionality not enabled.
Solution: Ensure the GPS antenna is properly connected and has a clear view of the sky to receive satellite signals. Verify that the GPS functionality is enabled by sending the appropriate AT commands to power on the GPS engine.
Where to buy the SIM5320

Resources
Similar sensors





