CODEWITHSUNDEEP
cmicrocontroller
a_chr1s
a_chr1s

Reputation: 25

Issue with " Error: '_asm': undefined identifier "

I have written out code to allow for an 8051 Microcontroller to be able to interface with an LCD and display a temperature that is read as an 8bit binary value on the LCD. The code was working when and was able to display text on the LCD however, when introducing code to allow for the temperature to be read, the program breaks. The error seems to be centralised around the function that reads the temperature from the ADC and seems to be about '_asm' which is something I have never dealt with before. The errors are listed below:

compiling main.c...
main.c(72): error C231: 'get_temp': redefinition
main.c(74): error C141: syntax error near 'int', expected '__asm'
main.c(74): error C202: 'readvalue': undefined identifier
main.c(75): error C141: syntax error near 'int', expected '__asm'
main.c(75): error C202: 'temp': undefined identifier
main.c(76): error C141: syntax error near 'int', expected '__asm'
main.c(76): error C202: 'binaryvalue': undefined identifier
main.c(76): error C141: syntax error near '{', expected 'sizeof'
main.c(76): error C141: syntax error near '}', expected ';'
main.c(77): error C141: syntax error near 'int', expected '__asm'
main.c(77): error C141: syntax error near '{', expected 'sizeof'
main.c(82): error C141: syntax error near '}', expected ';'
main.c(83): error C141: syntax error near '{', expected 'sizeof'
main.c(83): error C141: syntax error near ')', expected ';'
main.c(85): error C202: 'temp': undefined identifier
main.c(88): error C202: 'temp': undefined identifier
main.c(89): error C231: 'get_temp': redefinition
main.c(118): error C141: syntax error near 'int', expected '__asm'
main.c(118): error C202: 'atemp': undefined identifier
main.c(119): error C202: 'atemp': undefined identifier
main.c(120): error C202: 'atemp': undefined identifier

The Code has been developed in Keil uVision and is shown below. The function prototypes were commented out as they were causing further issues with the program and when commented out some errors were resolved:

#include<reg51.h>
#include<stdio.h>

/********************************************* LCD control signals declaration ***************************************************/
 
sbit RS = P0^0;     //
sbit RW = P0^1;  // Read/write line
sbit Enable = P0^2; // Enable line
#define LCD_PORT P2 // define port
 
/********************************************* LCD function prototypes ************************************************/
//void send_cmd(unsigned char);
//void send_char(unsigned char);
//void send_int()
//void LCD_init(void);
//void delayms(unsigned int);
//int get_temp();
////int get_humidity();

/******************************************* delayms Function declaration***********************************************/
void delayms(unsigned int val)
{
 unsigned int i,j;
   
 for(i=0;i<=val;i++)
 {
  for(j=0;j<=2;j++)  ;
  //_nop_();   // no operation produce 1us time delay
 }
  
}
/*********************************************LCD Command Sending Function declaration********************************/
 
void send_cmd(unsigned char Command)
{
 LCD_PORT = Command;
 RS = 0;      // Select Command Register
 RW = 0;    // write operation
 Enable = 1;      // High to Low pulse provided on the enable pin with nearly 1ms(>450ns)
 delayms(1);   // 1 millisec delay
 Enable = 0;
}
 

 

/********************************************* LCD Initialization Function declaration ********************************/
 
void LCD_init()
{
 send_cmd(0x38);      // configuring LCD as 2 line 5x7 matrix
 send_cmd(0x0E);      // Display on, Cursor blinking
 send_cmd(0x01);      // Clear Display Screen
 send_cmd(0x06);      // Increment Cursor (Right side)
}
 
void send_char(unsigned char character)
{
 LCD_PORT = character;
 RS = 1;    // Select Data Register
 RW = 0;    // write operation
 Enable = 1;      // High to Low pulse provided on the enable pin with nearly 1ms(>450ns)
 delayms(1);   // 1 millisec delay
 Enable = 0;
 delayms(10);   // 100 millisec delay
}
 
 


/****************************************** Temperature Function Declaration ********************************************/
void get_temp(){
    P1 = 0xFF;
    int readvalue = P1;
    int temp;
    int binaryvalue[70] = {01000001,00100001,01100001,00010001,10010001,11010001,10110001,11110001,00001001,01001001,00101001,01101001,11101001,10011001,01011001,00111001,01111001,11111001,10000101,01000101,00100101,10100101,01100101,00010101,10010101,11010101,00110101,01110101,01110101,00001101,10001101,01001101,11001101,00101101,01101101,01101101,11101101,00011101,01011101,01011101,11011101,00111101,10111101,01111101,11111101,11111101,00000011,10000011,10000011,01000011,11000011,00100011,00100011,10100011,10100011,01100011,11100011,11100011,11100011,00010011,00010011,10010011,10010011,01010011,01010011,11010011,11010011,11010011,00110011,00110011,10110011};
    int temperature[70] = {-20,-19,-18,-17,-16,-15,-14,-13,
                                            -12,-10,-9,-8,-7,-6,-5,-4,-3,-2,-1,
                                            0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,
                                            15,16,17,18,19,20,21,22,23,24,25,26,
                                            27,28,29,30,31,32,33,34,35,36,37,38,
                                            39,40,41,42,43,44,45,46,47,48,49,50};
    for(i=0;i<sizeof{binaryvalue};i++){
        if(readvalue == binaryvalue[i]){
            temp = temperature[i];
        }
    }
    return temp;
}

/********************************************* Main Funciton declaration ***********************************************/
void main()
{

    LCD_PORT = 0x00; // Make the port as output port
   
    LCD_init();            // LCD initialization
  send_cmd(0x80);     // Force cursor to beginning of 1st line, if the number is 0x83 then force the cursor to 53rd position
  delayms(100);    // Delay of 100millisec
  send_char('T');
    send_char('H');
    send_char('E');
    send_char('R');
    send_char('M');  // Send data
    send_char('I');
    send_char('S');
    send_char('T');
    send_char('O');
    send_char('R');  // Send data   
  send_cmd(0xC0);     // Force cursor to beginning of 2nd line
  delayms(100);    // Delay of 100millisec
  send_char('V');  // Send data 
  send_char('A');  // Send data 
  send_char('L');  // Send data 
    send_char('U');  // Send data 
  send_char('E');  // Send data 
  send_char(':');  // Send data
    int atemp = get_temp();
    while (atemp > 0){
        int k = atemp % 10;
        char send_x;
        itoa(k,send_x,10);
        send_char(send_x);
        temp /= 10;
    }
 //}
}

Any assistance would be greatly appreciated as my knowledge in C is limited. Thanks in advance.

Upvotes: 2

Views: 1777

Answers (1)

ralf htp
ralf htp

Reputation: 9422

_asm marks inline assembly and the correct syntax depends on the machine you use ( What is the difference between 'asm', '__asm' and '__asm__'? ). i do not know where you got the library with the LCD driver code from but inline assembly in Keil is described in https://www.keil.com/support/man/docs/armcc/armcc_chr1359124246903.htm and https://www.keil.com/support/man/docs/c51/c51_ap_ctoasm.htm (for 8051)

The error is in the lines

void get_temp(){
    P1 = 0xFF;
    _asm int readvalue = P1;
    _asm int temp;

i think you want to read or modify the P1 special function register (SFR) because it has a connection to your temperature sensor, for this see https://www.includehelp.com/embedded-system/accessing-ports-and-pins-in-8051-microcontroller.aspx

In addition you try an 8 bit value into an int that is at least 16 bit...

In addition you try to write/read the latch of P1, not read its value (https://developer.arm.com/documentation/ka004317/latest)

Upvotes: 1

Related Questions