Sim900a based on STM32 sends short messages in Chinese and English

Catalog

The first part 、 About SIM900A Basic knowledge of

1、SIM900A Mode of communication

2、SIM900A The power supply mode of the system

3、 Meaning of common instructions

The second part 、 Use the computer serial port assistant to realize SIM900A Send SMS in English and Chinese （ test SIM900A Module function ）

send out SIM Card detection instruction and signal quality detection instruction

One 、 Send English text messages

Two 、 Send Chinese text messages （ a key ） 

The third part 、STM32 drive SIM900A Send SMS in Chinese and English

1. Wiring mode of module and MCU  

2. Send English text messages

2. Send Chinese text messages

Last

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The first part 、 About SIM900A Basic knowledge of

1、SIM900A Mode of communication

        SIM900A Module adoption A serial port （UART） signal communication , Every SIM900A Development boards contain TTL Interface , The main use is 5VR（RXD） and 5VT（TXD）,3VR and 3VT Generally used, rarely used .

Serial chip USB-TTL Modules are recommended ft232>cp2102>ch340

2、SIM900A The power supply mode of the system

It is best to 5V2A The battery , Otherwise, there may be insufficient current to send text messages .5V1A It's fine too .

The following figure for External power supply mode Wiring diagram ： The power module in the figure goes to Taobao by itself “ Power conversion module 5V”, Search a lot .

  The following figure for USB—TTL Direct power supply The wiring diagram of ：

3、 Meaning of common instructions

AT+CPMS                       //  Inquire about SIM Use status of SMS in card 
AT+CNMI                       //  The new message indicates the setting 
AT+CMGF                       //  Select the SMS format  
AT+CSCS                       //  Encoding settings 
AT+CSCA                       //  Inquire about 、 Set up SMS Service center number 
AT+CSMP                       //  Set SMS text mode parameters 
AT+CMGS                      //  Send SMS 
AT+CMGR                      //  Read SMS 
AT+CMGD                      //  Delete SMS 
AT+CMGDA                     //  Delete all short messages 
AT&F                         //  Restore factory settings 
AT+CSQ                       //  Signal quality 

The second part 、 Using computers A serial port Assistant implementation SIM900A Send SMS in English and Chinese （ test SIM900A Module function ）

Mobile card is recommended ！！！ I used Unicom card and failed

It is recommended to use the serial port assistant provided by the seller , Otherwise, there may be confusion

send out SIM Card detection instruction and signal quality detection instruction

Be careful ： The signal quality value is 0—31 Between , The larger the signal, the stronger .0 Means no signal , Generally, this number should reach 10 above , The module can correctly perform functions such as sending text messages .

AT                       // Check send new line 
OK
AT+CPIN?                 //  Query whether SIM card 
+CPIN: READY
OK
AT+CSQ                    //  Query signal quality 
+CSQ: 18,0
OK

One 、 Send English text messages

AT+CSCS="GSM"
AT+CMGF=1
AT+CMGS="132******63"  // Phone number 
>okokok                // information content 
1A（ Check the serial port assistant 16 Base send ）

Send hexadecimal 0x1A Its meaning is to tell SIM900A Confirm sending , Then wait a few seconds , appear OK Means the delivery is successful. .

 

 

Two 、 Send Chinese text messages （ a key ） 

1、 Examples of mistakes
        I believe many people have read the data manual and PPT, Can successfully send English text messages, but can not successfully send Chinese text messages , I also stepped on this pit , According to customer service information PPT Routines given in , Failed to send Chinese SMS , Will be submitted to the ERROR error ！！！

as follows ： This is my routine of screenshots from the information given by customer service , The code is as follows

AT+CMGF=1
AT+CSCS="UCS2"
AT+CSMP=17,167,0,24
AT+CMGS="00310033003200320035003500360037003200360033"  // Of mobile phone number Unicode code 
> 4F60597D          // Content of short message （ Hello ）Unicode code 
ox1a                // Means to send 

        To tell you the truth, it's very stupid here , I spent the afternoon , At first I thought it was on SIM900A The card on is in arrears , It's useless for me to pay money , Then I searched the whole CSDN Community , I found that many old irons encountered the same problems as me , Then I happened to see this brother's blog ,Text Send Chinese SMS in mode （Sim900A R11.0）_boliu218 The blog of -CSDN Blog , A line of code configuration is found to be different from that in the routine , as follows ：

AT+CSMP=17,167,0,8          // Represents normal text mode 

          The difference here is the fourth parameter , Then I looked for the instruction manual for a detailed explanation of this instruction , The most important thing to pay attention to is ： The fourth parameter is 0 It means English mode , by 8 Represents Chinese normal text mode .

2、 Send a successful example
 

AT+CMGF=1
AT+CSCS="UCS2"
AT+CSMP=17,167,0,8 // Normal text mode 
AT+CMGS="00310033003200320035003500360037003200360033"  // Of mobile phone number Unicode code 
> 4F60597D          // Content of short message （ Hello ）Unicode code 
ox1a                // Means to send 

  Be careful ： Here we need to use Chinese Translation Unicode Coded software , The shopkeeper will give it

The third part 、STM32 drive SIM900A Send SMS in Chinese and English

About Unicode code
Unicode Basic introduction
Unicode Generally refers to unified code , It's also called the universal code 、 Single code , It's an industry standard in the field of computer science , Include character set 、 Coding scheme, etc .Unicode It is to solve the limitation of traditional character coding scheme , It sets a uniform and unique binary encoding for each character in each language , To meet cross language needs 、 Cross platform text conversion 、 Handling requirements .

1、 Encoding mode
unicode It is a character coding scheme developed by international organizations that can accommodate all characters and symbols .Unicode Use numbers 0-0x10FFFF To map these characters , Maximum capacity 1114112 Characters , Or there is 1114112 A code bit . A code point is a number that can be assigned to a character .UTF-8、UTF-16、UTF-32 They are all coding schemes that convert numbers to program data .

We put ASCII The string is converted into a double byte Chinese character unicode Code you find 1 This character becomes 0031
this 31 Did you think of something ,1 Of 16 No, it's just 0X31 Do you ？ Front complement 2 individual 0 The back is its 16 It's over ？

/**********************************************************************
 describe : ASCII  turn  unicode       such as  '1'   Turn into  "0031"
***********************************************************************/
void ASCII_TO_Unicode(char *ASCII,char *Unicode)
{
    int length;
    int i = 0;
    int j = 0;
	memset(Unicode,'\0',sizeof(Unicode));
    length = strlen(ASCII);

    for(i=0;i<length;i++)
    {
        Unicode[j++] = '0';
        Unicode[j++] = '0';

        Unicode[j++] = (ASCII[i] / 16) + 0x30;
        Unicode[j++] = (ASCII[i] % 16) + 0x30;
    }

}

 

1. Module and Single chip microcomputer Wiring mode  

        1、 The power supply of the single chip microcomputer is connected to the corresponding power supply

Single chip microcomputer PB10	Corresponding to	SIM900A The pins of 5VR
Single chip microcomputer PB11	Corresponding to	SIM900A The pins of 5VT
Single chip microcomputer GND	Corresponding to	modular GND
Single chip microcomputer 5V	Corresponding to	modular VCC_MCU

        2、 The module is powered separately

Modular VCC( or VCC5V)	Corresponding to	external DC5V
Modular GND	Corresponding to	External power supply GND

2. Send English text messages

/**************************************************************************/
// Function function ： Send English SMS function 
// The name of the function ：sim900a_send_English_message(char *message,char *phonenumber)(uint8_t number);
// Internal parameters ：message phonenumber
// modification date ：2022 year 1 month 26 Japan    In the morning 2：40、
// author ：       (CSDN search ) Big fart peach 
/**************************************************************************/
void sim900a_send_English_message(char *message,char *phonenumber)
{
 
	Usart_SendString2(USART3,"AT\r\n");                            //SIM900A Whether the connection with MCU is successful 
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));                      
	printf("English_message_OK1\r\n");
	
	Usart_SendString2(USART3,"AT&F\r\n");                           //SIM900A Reset 
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));                     // String matching function    
	printf("English_message_OK2\r\n");	
	
	Usart_SendString2(USART3,"AT+CSCS=\"GSM\"\r\n");               // English SMS instructions 1
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));                     
	printf("English_message_OK3\r\n");
	
	
	Usart_SendString2(USART3,"AT+CMGF=1\r\n");                     // English SMS instructions 2
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));  
	printf("English_message_OK4\r\n");
	
	sprintf(dispbuf,"AT+CMGS=\"%s\"\r\n",phonenumber);
	Usart_SendString2(USART3,dispbuf);                             // English SMS instructions 3
	delay_ms(200);
	while(Find_char((char*)Usart3_buff,"OK")); 
	printf("English_message_OK5\r\n");
	
	Usart_SendString2(USART3,message);                              // English SMS instructions 4
	delay_ms(200);
	while(Find_char((char*)Usart3_buff,"OK"));  
	printf("English_message_OK6\r\n");
	
	Usart_SendHalfWord(USART3,0x1a);                                // End order 
	delay_ms(2000);  // Two seconds later 
	while(Find_char((char*)Usart3_buff,"OK"));  
	printf("English_message_OK7\r\n");
} 

2. Send Chinese text messages

The difference between sending Chinese and sending English is that the phone number and content should be used Unicode coded , This requires conversion software , Or use the above conversion code . Secondly, there is one more line of code than sending English  Usart_SendString2(USART3,"AT+CSMP=17,167,0,8\r\n"); 

/**************************************************************************/
// Function function ： Send Chinese SMS function 
// The name of the function ：sim900a_send_Chinese_message(char *message,char *phonenumber)(uint8_t number);
// Internal parameters ：message phonenumber
// modification date ：2022 year 1 month 26 Japan    In the morning 2：40
// author ：       (CSDN search ) Big fart peach 
/**************************************************************************/
void sim900a_send_Chinese_message(char *message,char *phonenumber)
{ 
	
	Usart_SendString2(USART3,"AT\r\n");                           //SIM900A Whether the connection with MCU is successful 
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));                     // String matching function    
	printf("Chinese_message_OK1\r\n");
	
	Usart_SendString2(USART3,"AT&F\r\n");                          //SIM900A Reset 
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));                    
	printf("Chinese_message_OK2\r\n");	
	
	Usart_SendString2(USART3,"AT+CSCS=\"UCS2\"\r\n");               // Chinese SMS instructions 1
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));                       
	printf("Chinese_message_OK3\r\n");
	
	
	Usart_SendString2(USART3,"AT+CMGF=1\r\n");                     // Chinese SMS instructions 2
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));  
	printf("Chinese_message_OK4\r\n");
	
	Usart_SendString2(USART3,"AT+CSMP=17,167,0,8\r\n");            // Chinese SMS instructions 2
	delay_ms(200);	
	while(Find_char((char*)Usart3_buff,"OK"));  
	printf("Chinese_message_OK5\r\n");
	
	sprintf(dispbuf,"AT+CMGS=\"%s\"\r\n",phonenumber);
	Usart_SendString2(USART3,dispbuf);                             // Chinese SMS instructions 3
	delay_ms(200);
	while(Find_char((char*)Usart3_buff,"OK")); 
	printf("Chinese_message_OK6\r\n");
	
	Usart_SendString2(USART3,message);                              // Chinese SMS instructions 4
	delay_ms(200);
	while(Find_char((char*)Usart3_buff,"OK"));  
	printf("Chinese_message_OK7\r\n");
	
	Usart_SendHalfWord(USART3,0x1a);                                // Chinese end instruction 
	delay_ms(2000);  // Two seconds later 
	while(Find_char((char*)Usart3_buff,"OK"));  
	printf("Chinese_message_OK8\r\n");
} 

Last

In fact, I'm just an integrator

I have referred to many people's articles

【STM32 Training —SIM900A modular 1】 Second articles 、STM32 drive SIM900A Send SMS in Chinese and English _ Big fart peach's blog -CSDN Blog _stm32 Serial port to send Chinese characters

be based on STM32F103——SIM900A Send a text message + Serial printing _ Pica Churchill's blog -CSDN Blog _sim900a Send a text message