51 microcontroller connects to ESP8266 serial port WiFi module

　　51 microcontroller is the collective name for all microcontrollers compatible with the Intel 8031 ​​instruction system. The ancestor of this series of microcontrollers is Intel's 8004 microcontroller. Later, with the development of Flash rom technology, the 8004 microcontroller made great progress and became one of the most widely used 8-bit microcontrollers. Its representative model is the AT89 series of ATMEL Company. It is widely used in industrial measurement and control systems. Many companies have launched compatible models of the 51 series, which will occupy a large market for a long time in the future. The 51 microcontroller is a basic entry-level microcontroller, and it is also the most widely used one. It should be noted that 51 series microcontrollers generally do not have self-programming capabilities.

　　51 microcontroller difference

　　The same program will produce the same result when running on the hardware of various microcontroller manufacturers, such as ATMEL's 89C51 (discontinued), 89S51, PHILIPS, and WINBOND, etc. The 89C51 that we often say has been discontinued refers to ATMEL. The AT89C51 microcontroller has enhanced many features on the original basis, such as clock. What's even better is that the original ROM (one-time write) is replaced by Flash (the contents of the program memory can be rewritten at least 1000 times). The performance of AT89C51 It is very superior to 8051.

　　However, in terms of marketization, 89C51 has been challenged by the PIC microcontroller camp. The most fatal flaw of 89C51 is that it does not support ISP (online update program) function. New functions such as ISP function must be added to better continue the legend of MCS-51.

　　It is against this background that 89S51 replaced 89C51. 89S51 has become the new darling in the practical application market. Atmel, which has the largest market share, has discontinued AT89C51 and will replace it with AT89S51. 89S51 has been improved in the process. 89S51 adopts 0.35 new process, which reduces the cost and improves the functions to increase its competitiveness. 89SXX is backward compatible with 51 series chips such as 89CXX. At the same time, Atmel no longer accepts orders for 89CXX. The 89C51 you see on the market is actually a huge inventory of Atmel's early production. If the market demands it, Atmel can of course resume production of AT89C51.

　　51 microcontroller connects to ESP8266 serial port WiFi module

　　Pin connection

　　Burn firmware

　　Open the burning software, select the configuration tab, and click the small gear icon in the second column - load the firmware address

　　Click the selection bar for other options, uncheck it, and select only the second option (firmware address)

　　Return to the operation tab, select the correct COM port, and click one-click programming

　　The module is powered on again, the download starts, and waits for the download to complete.

　　Serial port assistant tests ESP8266 serial port WiFi module

　　Pin connection

　　Note: At this time, the connection status is WiFi module - "51 microcontroller -" serial port assistant (PC). Since the TXD and RXD of the WiFi module and the microcontroller are in a positive connection state, the microcontroller and the WiFi module do not communicate, which is equivalent to the WiFi module being directly connected to the serial port assistant.

　　AT common commands

　　The ESP8266 serial WiFi module is divided into three working modes: Station mode (similar to a wireless terminal), AP mode (providing wireless access services), and AP mode and Station mode.

　　When testing the WiFi module through the serial port assistant,

　　test

　　Send command: AT

　　Response: OK

　　Restart module

　　Send command: AT+RST

　　Response: OK

　　Setup module

　　Send command: AT+CWMODE = "mode"

　　Note: It takes effect after restarting (AT+RST)

　　"mode": 1-Station mode, 2-AP mode, 3-AP and Station mode.

　　Response: OK

　　Configure AP parameters

　　send command:

　　Command: AT+ CWSAP= "ssid", "pwd", "chl", "ecn"

　　Note: The command is only valid after the AP mode is turned on.

　　"ssid": string parameter, access point name

　　"pwd": string parameter, password up to 64 bytes, ASCII

　　"chl": channel number

　　"ecn": encryption mode, 0-OPEN, 1-WEP, 2-WPA_PSK, 3-WPA2_PSK, 4-WPA_WPA2_PSK

　　Example: AT+CWSAP="TEST","123456123456",1,3

　　Response: OK

　　Turn on multi-connection mode

　　Send command: AT+CIPMUX=《mode》

　　Description: "mode": 0-single connection mode, 1-multiple connection mode

　　Response: OK

　　Create server

　　Send command: AT+CIPSERVER=《mode》,《port》

　　Note: The server can be turned on only when AT+ CIPMUX=1; turning off the server mode requires a restart. After opening the server, server monitoring is automatically established. When a client accesses, a connection will be automatically occupied in sequence.

　　"mode": 0-turn off server mode, 1-turn on server mode

　　"port": port number, the default value is 333

　　Response: OK

　　Initialize WiFi module through 51 microcontroller

　　By testing AT commands through the serial port assistant, you can find that some AT commands will not be saved when the power is turned off, so initialization settings need to be made in the code.

　　Pin connection

　　Note: At this time, the connection status is WiFi module - "51 microcontroller -" serial port assistant (PC). Since the TXD and RXD of the WiFi module and the microcontroller are in the positive connection state, the microcontroller and WiFi module can carry out serial communication.

　　Implement code

　　#include《reg52.h》 //Commonly used header files for 51 microcontrollers

　　#define uchar unsigned char //Macro defines an unsigned char type

　　#define uint unsigned int //Macro defines an unsigned int type

　　//Send one byte

　　void sendByte（float b）

　　{

　　SBUF = b;

　　while (!IF);

　　TI = 0;

　　}

　　//Send string

　　void sendString（uchar *s）

　　{

　　while (*s != '') //The default end of the string is '', to determine the end of the string

　　{

　　sendByte（*s）;

　　s++;

　　}

　　}

　　//Initialize ESP8266WiFi module

　　void initEsp（）

　　{

　　uint a;

　　SCON = 0x50; //8-bit data, variable baud rate

　　TMOD = 0x20; //Set the timer 1-bit 16-bit automatic reload mode

　　TL1 = 0xfd; //Set the initial value of the timer, the baud rate is 9600

　　TH1 = 0xfd;

　　ET1 = 0; //Disable timer 1 interrupt

　　TR1 = 1; //Start timer 1

　　EA = 1;

　　for (a=0; a<50000; a++); //Delay for a few seconds to allow the module time to start

　　sendString(“AT+CWMODE=2”); //Set to softAP and station coexistence mode

　　//WiFi hotspot cannot be set through code. You can use the serial port assistant to set it up. The settings will not be lost when the power is turned off.

　　/*

　　for （a=0; a《20000; a++）;

　　sendString("AT+CWSAP='TEST','12345678',1,3"); //Establish WiFi hotspot

　　*/

　　for （a=0; a《50000; a++）;

　　sendString(“AT+CIPMUX=1”); //Start multiple connections

　　for （a=0; a《20000; a++）;

　　sendString("AT+CIPSERVER=1,333");//Establish server, port is 333

　　for （a=0; a《20000; a++）;

　　sendString(“AT+CIPSTO=50”); //Server timeout setting

　　RI=0;

　　ES=1; //Initialization completed, serial port interrupt is opened

　　}

　　//Main function

　　void main（）

　　{

　　initEsp（）;

　　}

　　Note: The baud rate in the code should match the baud rate of the serial port assistant, and some AT commands such as restarting the module and setting up WiFi hotspots cannot be used.

　　Get data transmitted by WiFi

　　As a TCP server, the ESP8266WiFi module will add +IPD, n, "string.length" by default before accepting information from the client: such characters should be paid attention to when processing.

　　Implement code

　　//Get data, data format example: +IPD, 0, 14: "time": "11:11"

　　void getData（）

　　{

　　uint a;

　　if（receiveFlag）

　　{

　　for（i=0; i《2; i++）

　　{

　　Hour［i］=Buffer［17+i］;

　　}

　　Hour［2］=‘’;

　　for（i=0; i《2; i++）

　　{

　　Minute［i］=Buffer［20+i］;

　　}

　　Minute［2］=‘’;

　　//Send the obtained data to the serial port assistant for display

　　for (a=0; a<10000; a++); //Delay is required, which may cause data confusion and packet loss.

　　sendString(Hour);

　　for （a=0; a《10000; a++）;

　　sendString（Minute）;

　　receiveFlag=0;

　　count=0;

　　for（i=0; i《22; i++）

　　{

　　Buffer［i］=0;

　　}

　　}

　　}

　　//Main function

　　void main（）

　　{

　　initEsp(); //Initialize WiFi module

　　receiveFlag = 0; //receiveFlag determines the flag for executing getData()

　　count = 0; //index of count buffer RXDdata[count]

　　while（1）

　　{

　　getData（）;

　　}

　　}

　　//Use interrupt to receive information and discard invalid information

　　void uart（） interrupt 4

　　{

　　if（RI == 1）

　　{

　　ES = 0; //Turn off serial interrupt

　　RI = 0; //Clear the serial port receiving flag bit

　　temp = SBUF; //Get data from the serial port buffer

　　if(count<20) //Satisfy the length of information to be received and store the data in the buffer

　　{

　　Buffer［count］=temp;

　　count++;

　　if (Buffer[0]=='+') //Determine whether it is invalid data, because the WiFi module will automatically add a string starting with "+PID.."

　　{

　　receiveFlag = 1;

　　}

　　else

　　{

　　receiveFlag = 0;

　　count = 0;

　　}

　　}

　　ES = 1;

　　}

　　}