若该文为原创文章，转载请注明原文出处。

以前使用SIM900A模块和Air724模块发送短信，随着2G停了，SIM900A不在使用，Air724价格浮动变化，一直在寻找Cat1替换模块，所需要的功能不多，只要能上网，能发短信，能打电话，最好有TTS功能。

一、对比

Air780不支持电话，但也够用了，电话功能可以EC600M等模块。

这里记录Air780发送短信功能

参考：

AT固件发短信测试实例

二、发送流程

注意:4G模块在上电、重启的时候，主动发出开机日志，这些日志一般需要过滤。然后再去执行AT命令。

按流程操作。

三、STM32代码移植

测试的是发送中文短信

1、初始化串口

STM32和4G通过使用的是串口通讯

这是使用PA2 PA3穿孔2

void GSM_USART_Init(uint32_t bound)
{  
	NVIC_InitTypeDef NVIC_InitStructure;
	GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;

	GSM_USART_GPIO_APBxClkCmd(GSM_USART_GPIO_CLK, ENABLE);
	GSM_USART_APBxClkCmd(GSM_USART_CLK,ENABLE);

 	USART_DeInit(GSM_USARTx); 
	//USART_TX
	GPIO_InitStructure.GPIO_Pin = GSM_USART_TX_GPIO_PIN;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_Init(GSM_USART_TX_GPIO_PORT, &GPIO_InitStructure);
	//USART_RX
	GPIO_InitStructure.GPIO_Pin = GSM_USART_RX_GPIO_PIN;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
	GPIO_Init(GSM_USART_RX_GPIO_PORT, &GPIO_InitStructure);
	
	USART_InitStructure.USART_BaudRate = bound;
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;
	USART_InitStructure.USART_StopBits = USART_StopBits_1;
	USART_InitStructure.USART_Parity = USART_Parity_No;
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;	
	USART_Init(GSM_USARTx, &USART_InitStructure);
	
	USART_Cmd(GSM_USARTx, ENABLE);
	USART_ITConfig(GSM_USARTx, USART_IT_RXNE, ENABLE);
	
	NVIC_InitStructure.NVIC_IRQChannel = GSM_USART_IRQ;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);	//
	
	GSM_USART_RX_STA=0;
}

调用方式

GSM_USART_Init(38400);

模块会自动适配波特率，正常使用115200

2、初始化

delay_ms(3000);
delay_ms(2000);
while(GSM_send_cmd("AT\r\n","OK",100));		
delay_ms(100);

// 检测有没有卡		
while(GSM_send_cmd("AT+CPIN?\r\n","OK",100));		
delay_ms(100);

初始化功能比较简单，没做过多处理，判断有没有卡。

3、发送短信

void sim900a_send_Chinese_message(char *message,char len,char *phonenumber)
{ 
 u8  cnt = 3;
	u8 p[128] = {0};
	while(GSM_send_cmd("AT+CPIN?\r\n","OK",100));		
	delay_ms(100);
	while(GSM_send_cmd("AT&F\r\n","OK",100));	
	delay_ms(100);
		while(GSM_send_cmd("AT+CSMS=1\r\n","OK",100));	
	delay_ms(100);
	while(GSM_send_cmd("AT+CMGF=1\r\n","OK",100));	
	delay_ms(100);
	while(GSM_send_cmd("AT+CSMP=17,167,0,8\r\n","OK",100));	
	delay_ms(100);
	
	memset(p, 0, 128);
	sprintf((char*)p,"AT+CMGS=\"%s\"\r\n",phonenumber); // 设置目标手机号
	while(GSM_send_cmd(p,">",100));  
	delay_ms(200);
	
	//sprintf((char*)p,"%s\r\n",message); // 设置发送内容
	//GSM_send_cmd(message,">",100);  
	usart2_send(&message[0], len);
 delay_ms(200);
	USART_SendData(USART2, 0x1a); // 确认发送
	delay_ms(200);
} 

调用

sim900a_send_Chinese_message(Chinese_message1, sizeof(Chinese_message1), Unicode_phonenumber);

其中：

char Chinese_message1[20] = {0x80,0x01,0x4E,0xBA,0x8D,0xCC,0x50,0x12,0xFF,0x0C,0x8B,0xF7,0x6C,0x42,0x5E,0x2E,0x5F,0xD9,0x00,0x20}; 为Unicode编码

char Unicode_phonenumber[]={"1875XXXXXXX"};为电话号码，电话号码不用转Unicode编码。

中文发送短信发送使用UCS2，接收中文短信是GB2312编码。

如有侵权，或需要完整代码，请及时联系博主。