[PIC] Read RS232 using PIC16F877A

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kirankumar.t2

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Hi All,

I am new to this microcontroller world, I need support form you all.

I need to make a simple PIC program to ead RS232 data using PIC16F877A, the RS232 data formate is as shown below

Date time voltage currrent
22/10/2013 10:10am 18.05V 20.05A
22/10/2013 10:15am 18.05V 20.05A
22/10/2013 10:20am 18.05V 20.05A
......

RS232 data will be continuously available to PIC for Every 5s once,

if any one of the RS232 data either voltage or current dcross the limit ( 16 V- 19 V ) or ( 19A - 21 A) then Port B first pin should go high ( any port is ok ).

Many thanks in advance.

Regards
Ponnkatt
 

As the data you are sending is in string format use UART receive interrupt to receive data into a buffer (char array) of say 40 bytes. You then have to parse this string and extract voltage and current values to wo temp buffers of size say 8 bytes and then subtract 0x30 from each element if it is not decimal point. convert the elements in array to a float value. You can then compare these values with limit values.
 

simply use microC, there is a library function to do this job and also use MAX232 in hardware in between MCU and PC. Its simple.

Here is a sample code. Hope it will help you...
Code: 
/*******************************************************************************
Program for PC Based Load Control
Program Written by_ Engr. Mithun K. Das
Email: [email]mithun060@gmail.com[/email] Cell: +8801722448270;
MCU: PIC16F73; X_Tal: 8MHz;
Date: 28/10/2013;
*******************************************************************************/

unsigned char uart_rd;     // read the received data,

void main() 
{
   //Initialize the USART
   UART1_Init(9600);
   //Write Some lines of TEXT
   UART1_Write_Text(" ");
   UART1_Write_Text(" PC Based LOAD Control");
   UART1_Write_Text(" ");

    Delay_ms(1000);
    TRISB = 0x00;//all out
    PORTB = 0x00;
    while (1)
    {
        if (UART1_Data_Ready())
        { // If data has been received
            uart_rd = UART1_Read();     // read the received data,
            if(uart_rd=='1') RB0_bit = ~RB0_bit;
            if(uart_rd=='2') RB1_bit = ~RB1_bit;
            if(uart_rd=='3') RB2_bit = ~RB2_bit;
            if(uart_rd=='4') RB3_bit = ~RB3_bit;
        }


        Delay_ms(100);
    }
}
 

If your data format is fixed then try attached hex file. I have compiled for PIC18F45K22, 4 MHz external clock. Proteus file attached. test.hex doesn't read UART. Run.hex reads UART. Test.hex extracts data from a fixed string for testing purpose. Use Run.hex in hardware and reply.

 

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  • Proteus.rar
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  • vi_test.png
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many thanks for the support,

I am using PIC simulater IDE for simulation, in this simulator i don't have
PIC18F45K22, please let me know how to check with present simulator

Regards,
Ponnkatt
 
Last edited:

I can compile code for any other PIC18(L)F devices. Mention the PIC18(L)F available in PIC Simulator IDE and also Fosc and baudrate. I will compile and post hex file for testing. I tested code with PIC16F and it doesn't work as expected because I got "IRP_bit must be set manually in code" warning in mikroC Compiler. Use PIC18F device for testing in Simulator and also in hardware.


Edit: You have to use Proteus 7.10 or newer or PIC 18 Simulator IDE. Both support PIC18F46K22.
 
Last edited:

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Hi Milan,

Can you send me the PIC16F source code for the above program,

Regards
Ponnkatt
 

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