51 single chip microcomputer temperature alarm based on WiFi control

be based on wifi The control of the 51 MCU temperature alarm

Beginner's notes , There are inevitably many mistakes . Forget that you guys will not hesitate to give advice after finding mistakes

The author is not an electrical major , There is no knowledge support in many places , It is inevitable to make mistakes or explain ambiguities

Links to a full set of materials ： Baidu SkyDrive

My applet source code ： Click extract

1、 Function is introduced

1. Expand the display to show the current temperature and threshold temperature .
2. When the temperature exceeds the set threshold, the buzzer will alarm .
3. Can pass wifi Use the mobile interface to adjust parameters .

Because there were several experiments before, the mobile phone could not be connected to the MCU , I thought wifi The function of can only change the level of hardware . But after experimental tests ,wifi The function of can directly put statements . So the logic is simple , direct if-else Dafa .

2、 Introduction to logical structure

adopt wifi The incoming characters change the existing program if else Dafa

3、 MCU pre knowledge

3.1 Why choose SCM

SCM can Collect data from reality And through the program to deal with . Make electronic devices more intelligent through program control . It is convenient for people's life .

3.2 What is single chip microcomputer .

1. In my eyes, SCM is a microcomputer .
2. It has some extended interfaces, such as ： display 、 Temperature collector 、 bluetooth 、wifi etc. . These extenders give the single chip microcomputer more powerful functions .
3. Strong electrical characteristics . Change the electrical characteristics of a certain position through the program to realize the function .

Roast can only be used C The ancient grammar of language .

3.3 How to use SCM

After the electrical details are encapsulated into a small black box, the program becomes a tone API Write C Language applet .

But if you don't understand the underlying electrical principle, you will overturn ~, For details, see the following “4.3 Show function “

1. Software direction requires programming foundation （51 The language of MCU is C）
2. Hardware direction requires understanding board principle .（ The author said he couldn't understand （ I'm not going to understand ））

4、 The overall development process

Sensor and IO The communication of the mouth is very difficult to understand , This is also one of the ideas that cut me off from learning hardware ~~

But but but Communication can hardly be changed , That is to say, directly transfer what others have written API That's it

4.1 What is in the main function

1. Capture the current temperature and display plus to judge whether to alarm
2. Capture the interrupt and enter the edit threshold mode

4.2 Realize the capture temperature function

It uses DS18B20 Temperature sensor . Determine the calculation formula according to the hardware characteristics 、 Timing controls the process of temperature reading

4.3 Implement the display function

Used to display prompt information and input information .

use LCD1602 Liquid crystal display (LCD) . Only English can be displayed . Here, the screen is not cleared after the display, and the car overturns .

4.4 Implement the alarm function

if Judge , If the temperature is higher than the threshold, the buzzer will vibrate .

4.5 Realize the modification of threshold function

Pass in the parameter ： Letter

1. A： Enter editor
2. B： Exit the editor
3. C： Delete a bit
4. D： decimal point
5. similar ‘1’： Numbers

Realization way ： Array sentry

Show function after each call

4.6 Realization wifi The incoming data enters the modified threshold function

At first, the store sent me wifi Something is wrong with the module , For a day , After the communication failed, he gave a well grounded negative comment , The store owner reissued a good module :happy:.

if - else Call the modify threshold function . The point is wifi Communication for . The use of wifi The module is ESP8266-WIFI.

Communication needs to be guaranteed wifi The baud rate is the same as that of MCU .

Function by sending AT+CIPSEND=0,7 Instructions , Set the sending data length , Then send the data To WIFI modular .

commonly APP The format of the sent data is ：+IPD,ID Number , Send data length : data .

When the mobile phone is successfully connected to the hotspot , among +IPD,ID The number is fixed , Users can send How much data , Then the length can be determined . In this way, the serial port receiving interrupt can follow this format To analyze , Our main concern is “ data ” That piece of .

For example, control in the experiment in the supporting materials LED1 On command ：+IPD,0,1:1 Each data is 10 Characters . The data is s[9] 了 .

5、 Summary

The final code still has large and small bug, It can only be said that I can barely run .

Through half a month of single-chip learning , I know more about software control . I also have some knowledge of hardware .