PIC16F877A serial port transmission-EEWORLD

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PIC16F877A serial port sending and querying methods. It took me a day to find out this. It turned out to be a problem with the serial port chip voltage. The summary is as follows:

1. Pay attention to the power supply voltage of the 232 serial port chip, there are 5V and 3.3V

2. Pay attention to the TXD and RXD wiring. The TXD of the microcontroller is connected to the R2OUT of the 232 chip, and the RXD of the microcontroller is connected to the T2IN of the 232 chip.

3. Note that the UTXD of ESP8266 is connected to the RX of MCU, and the URXD is connected to the TX of MCU.

4. Note that the UTXD of ESP8266 is connected to the T2IN of 232, and the URXD is connected to the R2OUT of 232

5. Set the serial port baud rate to 9600

6. Pay attention to the reliability of the connection line. If you use a wire connection, be sure to check whether the wire and the socket are stably connected.

7. System connection is shown in the figure below

PIC16F877A serial port transmission - allegro_tyc - allegro_tyc's blog

//The following is the serial port sending program

#include

#define uchar unsigned char

#define uint unsigned int

__CONFIG(0x3B32);

void delay2ms(uint x)

{

uint a,b;

for(a=x; a>0; a--)

for(b=152; b>0; b--);

}

void UART_SendByte(unsigned char dat)

{

TXREG=that;

while(TRMT==0);

}

void serial_init()

{

TRISC=0xbf; //Set RX as input and TX as output

TXSTA=0x24;

RCSTA=0x80;

SPBRG=0x33;//I use 8MHz crystal, 9600=8000000/(16*(X+1))->X=51->X=0x33

GIE=1;

LIKE=1;

RCIE=1;

}

void main()

{

serial_init();

while(1)

{

UART_SendByte(0x31);

UART_SendByte(0x32);

UART_SendByte(0x33);

delay2ms(500);

}

//The following is the program for MCU to send AT naming to ESP8266

#include

#define uchar unsigned char

#define uint unsigned int

#define LED RD1

__CONFIG(0x3B32);

#define LED_OPEN() (LED=1)

#define LED_CLOSE() (LED=0)

#define CPU_FOSC 8000000

#define BAUD 9600

unsigned char* LYMS="AT+CWMODE=3\r";

unsigned char* SZLY="AT+CWSAP=\"ESP8277_CYT\"\,\"1234567890\"\,11\,3\r";

unsigned char* RST="AT+RST\r";

unsigned char* LCAP="AT+CWLAP\r";

unsigned char* SZDLJ="AT+CIPMUX=1\r";

unsigned char* KQFU="AT+CIPSERVER=1\,5000\r";

unsigned char* FSSJ="AT+CIFSR\r";

void delay2ms(uint x)

{

uint a,b;

for(a=x; a>0; a--)

for(b=152; b>0; b--);

}

void sys_init()

{

TRISD=0x00; //Set PORTD to output

}

void usart_init()

{

TRISC=0xbf; //Set RX as input and TX as output

TXSTA=0x24;

RCSTA=0x80;

SPBRG=0x33; //I use 8MHz crystal oscillator, 9600=8000000/(16*(X+1))->X=51->X=0x33

GIE=1;

LIKE=1;

RCIE=1;

}

void usart0_putchar(unsigned char data)

{

while (!TRMT);

TXREG = data;

}

void print(unsigned char* p_string)

{

while (*p_string)

{

if (*p_string != '\r')

{

usart0_putchar(*p_string);

}

else

{

usart0_putchar('\r');

usart0_putchar('\n');

}

p_string++;

}

void send_command()

{

print(LYMS);delay2ms(500);delay2ms(500);

print(SZLY);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(RST);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(LCAP);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(SZDLJ);delay2ms(500);delay2ms(500);

print(KQFU);delay2ms(500);delay2ms(500);

print(FSSJ);delay2ms(500);delay2ms(500);

}

void main()

{

sys_init();

usart_init();

send_command();

while(1)

{

PORTD = 0xff;

delay2ms(500);

PORTD = 0x00;

delay2ms(500);

}

//The following is the program for MCU to send AT command to ESP8266, receive command, parse and respond

#include

#define uchar unsigned char

#define uint unsigned int

unsigned char RX_Buffer[32];

unsigned char RX_CNT=0;

#define LED1 RD1

#define LED2 RD2

#define LED3 RD3

__CONFIG(0x3B32);

#define LED1_OPEN() (LED1=1)

#define LED1_CLOSE() (LED1=0)

#define LED2_OPEN() (LED2=1)

#define LED2_CLOSE() (LED2=0)

#define LED3_OPEN() (LED3=1)

#define LED3_CLOSE() (LED3=0)

#define CPU_FOSC 8000000

#define BAUD 9600

unsigned char* LYMS="AT+CWMODE=3\r";

unsigned char* SZLY="AT+CWSAP=\"ESP8277_TYC\"\,\"1234567890\"\,11\,3\r";

unsigned char* RST="AT+RST\r";

unsigned char* LCAP="AT+CWLAP\r";

unsigned char* SZDLJ="AT+CIPMUX=1\r";

unsigned char* KQFU="AT+CIPSERVER=1\,5000\r";

unsigned char* FSSJ="AT+CIFSR\r";

void delay2ms(uint x)

{

uint a,b;

for(a=x; a>0; a--)

for(b=152; b>0; b--);

}

void sys_init()

{

TRISD=0x00; //Set PORTD to output

}

void usart_init()

{

TRISC=0x80; //Set RX as input and TX as output

TXSTA=0x24;

RCSTA=0x90;

SPBRG=0x33; //I use 8MHz crystal oscillator, 9600=8000000/(16*(X+1))->X=51->X=0x33

RCIE=0x01;

TXEN=0x01;

TXIE=0x01;

PEIE=0x01; //External interrupt enable

GIE=1; //General interrupt enable

}

void usart0_putchar(unsigned char data)

{

while (!TRMT);

TXREG = data;

}

void print(unsigned char* p_string)

{

while (*p_string)

{

if (*p_string != '\r')

{

usart0_putchar(*p_string);

}

else

{

usart0_putchar('\r');

usart0_putchar('\n');

}

p_string++;

}

void send_command()

{

print(LYMS);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(SZLY);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(RST);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(LCAP);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(SZDLJ);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(KQFU);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

print(FSSJ);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);delay2ms(500);

}

void interrupt usart(void)

{

if(RCIE&&RCIF)

{

//TXREG = RCREG;

RX_Buffer[RX_CNT] = RCREG;

if(RX_Buffer[0]==0x45)

RX_CNT++;

else

RX_CNT=0;

if(RX_CNT>=10)

{

if(RX_Buffer[0]==0x45&&RX_Buffer[1]==0x53&&RX_Buffer[2]==0x50)

{

if(RX_Buffer[4]==0x4C&&RX_Buffer[5]==0x45&&RX_Buffer[6]==0x44)

{

if(RX_Buffer[7]==0x31)

{

if(RX_Buffer[3]==0x4B)

LED1_OPEN();

if(RX_Buffer[3]==0x47)

LED1_CLOSE();

}

RX_CNT=0;

}

void main()

{

sys_init();

usart_init();

send_command();

LED1_OPEN();

LED2_OPEN();

LED3_OPEN();

while(1);

}

Keywords：PIC16F877A Reference address：PIC16F877A serial port transmission

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