[MCU] 51 MCU burning those things

Pre tutorial

• 【 Single chip microcomputer 】51 Summary of single chip microcomputer use

Preface

   On a whim recently, I want to study 51 Single chip microcomputer installation system , So I bought one 51 The minimum system board of single chip microcomputer , As shown in the figure below .

I also bought one STC86C52, I plan to experiment with this single chip microcomputer . But unfortunately , First step —— There is a problem with the burning program , So I spent several hours searching for relevant information , Meanwhile, I also studied other models 51 Download mode of MCU .

51 There are several ways to download SCM ？

It is suggested to read this blog before reading ：【 The embedded 】 A thorough understanding of MCU program burning

   For this question , The most important thing is to distinguish models . First, let's talk about the older ATmel Of AT89S52, This type of single chip microcomputer adopts SPI agreement For program writing , That is, the one on the right in the above figure 10 One pin . Although it uses more pins than SPI many , But its essence is based on SPI agreement .
   And for the still widely used STC Of 51 Single chip microcomputer , Usually download programs through serial port , It's using Bootstrap The way of burning . But there are two kinds , One is cold start , One is hot start .

STC89C52

   First, Cold start , because STC SCM is based on serial port to download , And its internal boot program has been solidified , Every time you power on and reset , The system first executes the boot program , Check whether there are download instructions , without , Continue to execute the user program , If there is , Then update the program , The execution logic is shown in the figure below .【 The picture is from the official website manual 】

therefore , In actual use , Because the bootstrap executes too fast , You need to click the download button on the upper computer first , At this time, the upper computer began to transmit instructions to the MCU to download the program （0x7F）, Then power on to start from the boot program , In this way, you can realize the cold start to download the program .

attach ：STC What is the difference between cold start and reset of single chip microcomputer

   however , What needs to be noted here is , General USB turn TTL Modules cannot be used to STC Of 51 SCM download program ！ The circuit must be slightly modified , Refer to the official website manual , As shown in the figure below .

   If it's general USB turn TTL The module will be connected only TXD,RXD,GND The chip will also have electricity （ because TXD and RXD All are 5V）, This phenomenon is called Serial port leakage , This will cause the chip to remain in a state of power , Thus, it cannot be cold started . So generally speaking 51 The cold start burning circuits of single chip microcomputer have been arranged , It is estimated that no one will specially make one that only applies to STC MCU program burning USB turn TTL modular .

   Find a tutorial , This download circuit and related theoretical knowledge are introduced in detail , It is suggested that those who want to draw their own board can look at it in combination with the official manual .  attach ： link

   This cold start download procedure is a little complicated , Need to power on and power off repeatedly , Therefore, there is another download method that can realize hot start , That is, the program update operation can be completed without powering down , The principle of this implementation is STC There are registers in the single chip microcomputer, which can make the chip execute from the boot program . As shown in the figure below .

The specific practice of this method remains to be studied , Take a look at the following links

• STC Cold free start burner DIY - CSDN
• STC Power free automatic program download - CSDN

Latest test //2022.7.18

   I tried again today STC89C52 Serial port download , It's easy to find out by accident ！ When I wrote this blog before, I found that I usually bought it USB The module to serial port cannot be directly used to STC89C52 Download the program's , But I tried it today and found it was possible ！, Although there will be serial port leakage , That is, the power indicator is half on , But it can be burned into the program ！ Make a note of .

AT89S52

   After that, the commonly used STC Single chip microcomputer , Let's talk about the older AT89S52. The burning mode of this type of MCU is based on SPI agreement , That's what it is 10 Pin interface . This kind of MCU needs to be bought USBisp perhaps USBasp equipment , As shown in the figure below .

   The corresponding upper computer is ProgISP, Here is a software station Download link , It's still relatively clean . At present, there are mainly two versions circulating on the Internet ：1.72 and 2.0, It is recommended to use 1.72 Version of , because 2.0 Version does not support USBasp. Open software , The interface is shown in the figure below .

First of all, pay attention to that program state, If Programmer inserted （USBasp or USBisp） And the one on the left PRG The icon of is colored , All is well , It shows that your current programmer can use , If it's gray , Then start troubleshooting , First determine Is the driver installed , because USBasp You need to install the driver , Personally, I don't recommend looking for someone else to download a good driver file , Then you use this to update the driver . A better solution is to use software Zadig, This software is very common , It is mainly used to install some USB The driver , Here is also a software station Download link , It's very clean .
   If the driver has been installed but it is difficult to use , It is recommended to delete the device in the device manager first , Then install the drive . Start by opening Zadig, Then insert USBasp, You can find it in its list USBasp The option to , Then install the drive as shown in the figure below .

If there is no device in the list , You can click on option, choice List All Devices, As shown in the figure below .

   After installing the drive , It can be restarted ProgISP try , See if that icon is still gray , If something goes wrong , That's basically a hardware problem , I have to buy another .