STC12 MCU realizes automatic program download

There are two program areas in the STC microcontroller, the user program area and the ISP program area.

After the microcontroller is powered on (cold start, not external manual reset or watchdog reset), the ISP program will be run first to detect whether there is a legal download command flow, which takes tens to hundreds of milliseconds. 

If there is no legitimate download command stream, the user program is run immediately. 

If there is a legitimate download command stream, the ISP monitoring program starts to communicate with the ISP download software, and the software also enters the programming mode and sends the program code to the monitoring program. The monitoring program receives the program code and writes it into the user program area. 

After programming is completed and the program is successfully verified, the user program takes effect immediately and starts running.

If the IAP_CONTR register is not set in the software through the serial port with the host computer (such as the following program), when STC-ISP tries to handshake with the MCU, it will continuously send the "0x7F" signal from the serial port at the baud rate in the "minimum baud rate" setting item until the power-on cold start (or soft reset to ISP) detects the download command flow for tens to hundreds of milliseconds, and then stops sending the "0x7F" signal. 

If IAP_CONTR is set, the corresponding setting related commands will be executed.

#include

unsigned char RevData;

//void UartInit()   

//{

// PCON &= 0x7F;   

// SCON = 0x50;    

//AUXR &= 0xBF;   

// AUXR &= 0xFE;   

// TMOD &= 0x0F;   

// TMOD |= 0x20;   

// TL1 = 0xFD; 

//TH1 = 0xFD; 

//ET1 = 0;        

// TR1 = 1;        

//}

void UartInit()

{

    AUXR &= 0xF7;       

    S2CON = 0x50;       

    AUXR &= 0xFB;       

    BRT = 0xFD; 

    AUXR |= 0x10;   

}

void main()

{

    UartInit();

    EA = 1;

    ES = 1;

    P0 = 0;

    while(1);

}

void Uart() interrupt 4

{

    if(RI)

    {

        RI = 0;

        RevData = SBUF;

        if(RevData == 0x0a)

        {

            IAP_CONTR=0x60; 

        }

    }

    if(TI)

    {}

}