SIM900 / SIM900A GSM/GPRS Module

#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 = 9600,
        .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_sim900() {
    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_sim900();

    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);
    }
}

uart:
  tx_pin: GPIO17  # module RXD
  rx_pin: GPIO16  # module TXD
  baud_rate: 9600

# ESPHome's sim800l component speaks the generic SIM AT command set
sim800l:
  on_sms_received:
    - logger.log:
        format: "Received '%s' from %s"
        args: [ 'message.c_str()', 'sender.c_str()' ]

[env:sim900]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200

#include <HardwareSerial.h>
#include <Arduino.h>

HardwareSerial sim900(1);
#define PWRKEY 4

void power_on_sim900() {
    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);
    sim900.begin(9600, SERIAL_8N1, 16, 17); // RX, TX
    power_on_sim900();

    // Test AT command
    sim900.println("AT");
    delay(1000);
    while (sim900.available()) {
        Serial.write(sim900.read());
    }

    // Send SMS
    sim900.println("AT+CMGF=1"); // Set SMS to text mode
    delay(1000);
    sim900.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's number
    delay(1000);
    sim900.print("Hello from SIM900");
    sim900.write(26); // CTRL+Z to send SMS
    delay(5000);
}

void loop() {
    // Handle incoming data or other functionalities
}

from 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_sim900():
    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_sim900()

# 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))