0
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Lately I've been trying to interface HC-SR04 with PIC16F877A using capture mode and interrupt but am getting "Warnings" and I've pasted the code below:

Compile output:

"C:\Program Files (x86)\Microchip\xc8\v1.10\bin\xc8.exe" --pass1  --chip=16F877A -Q -G --asmlist  --double=24 --float=24 --emi=wordwrite --opt=default,+asm,-asmfile,-speed,+space,-debug,9 --addrqual=ignore -P -N31 --warn=0 --summary=default,-psect,-class,+mem,-hex,-file --runtime=default,+clear,+init,-keep,-no_startup,+osccal,-resetbits,-download,-stackcall,-config,+clib,-plib "--errformat=%%f:%%l: error: %%s" "--warnformat=%%f:%%l: warning: %%s" "--msgformat=%%f:%%l: advisory: %%s"  -obuild/default/production/Ultrasonic.p1  Ultrasonic.c 

Ultrasonic.c:23: warning: unknown pragma "code"
Ultrasonic.c:29: warning: unknown pragma "interrupt"
Ultrasonic.c:36: warning: unknown pragma "code"
Ultrasonic.c:64: warning: illegal conversion between pointer types
pointer to const unsigned char -> pointer to unsigned char
Ultrasonic.c:66: warning: illegal conversion between pointer types
pointer to const unsigned char -> pointer to unsigned char
Ultrasonic.c:83: warning: implicit conversion of float to integer
Ultrasonic.c:88: warning: illegal conversion between pointer types
pointer to const unsigned char -> pointer to unsigned char
Ultrasonic.c:92: warning: illegal conversion between pointer types
pointer to const unsigned char -> pointer to unsigned char
"C:\Program Files (x86)\Microchip\xc8\v1.10\bin\xc8.exe"  --chip=16F877A -G --asmlist -mdist/default/production/Ultrasonic.X.production.map  --double=24 --float=24 --emi=wordwrite --opt=default,+asm,-asmfile,-speed,+space,-debug,9 --addrqual=ignore -P -N31 --warn=0 --summary=default,-psect,-class,+mem,-hex,-file --runtime=default,+clear,+init,-keep,-no_startup,+osccal,-resetbits,-download,-stackcall,-config,+clib,-plib "--errformat=%%f:%%l: error: %%s" "--warnformat=%%f:%%l: warning: %%s" "--msgformat=%%f:%%l: advisory: %%s"   -odist/default/production/Ultrasonic.X.production.cof  build/default/production/Ultrasonic.p1     
Microchip MPLAB XC8 C Compiler (PRO Mode)  V1.10
Copyright (C) 2012 Microchip Technology Inc.
Ultrasonic.c:21: warning: variable "_rf" is not used

Memory Summary:
    Program space        used   3F1h (  1009) of  2000h words   ( 12.3%)
    Data space           used    3Ch (    60) of   170h bytes   ( 16.3%)
    EEPROM space         used     0h (     0) of   100h bytes   (  0.0%)
    Configuration bits   used     0h (     0) of     1h word    (  0.0%)
    ID Location space    used     0h (     0) of     4h bytes   (  0.0%)

make[2]: Leaving directory `E:/MPLAB Projects/Ultrasonic/Ultrasonic.X'
make[1]: Leaving directory `E:/MPLAB Projects/Ultrasonic/Ultrasonic.X'

BUILD SUCCESSFUL (total time: 6s)
Loading code from E:/MPLAB Projects/Ultrasonic/Ultrasonic.X/dist/default/production/Ultrasonic.X.production.hex...
Loading symbols from E:/MPLAB Projects/Ultrasonic/Ultrasonic.X/dist/default/production/Ultrasonic.X.production.cof...
Loading completed

I've read your previous posts but still couldn't resolve the problem and I've never used #pragma directive before please help me to resolve this problem. I've pasted the code and any help will be appreciated a lot.

Code

#include <pic.h>
#include <htc.h>
#define TRIG RB7
#define PD PORTD
#define RS RE0
#define RW RE1
#define E RE2
void cmdwrite(unsigned char);
void datawrite(unsigned char);
void strdis(unsigned char *str);
void MSDelay(unsigned int itime);
void ms_delay();
/*void msd();*/
void dis4digit(unsigned int var);
void CCP1_ISR(void);
void rising(void);
void falling(void);
void chk_isr();
void My_HiPrio_Int();
unsigned char disp=0;
unsigned char rf=0;

#pragma code My_HiPrio_Int=0x0008
void My_HiPrio_Int(void)
{
    chk_isr();
}

#pragma interrupt chk_isr
void chk_isr(void)
{
     if(CCP1IF==1)
       CCP1_ISR();
}

#pragma code
void main()
{
unsigned long int distance_in_cm;
unsigned long int distance_in_inches;
unsigned long int F_byte;
unsigned char H_byte,L_byte;

      ADCON1=0x0F;
      GIE=1;
      PEIE=1;
      CCP1IE=1;
      TRISD=0;
      TRISE=0;
      TRISB7=0;
      TRISC2=1;
      CCP1CON=0x05;
      T1CON=0x00;
      CCPR1L=0x00;
      CCPR1H=0x00;
      TRIG=0;
      E=0;
      cmdwrite(0x01);
      cmdwrite(0x38);
      cmdwrite(0x38);
      cmdwrite(0x38);
      cmdwrite(0x0C);
      cmdwrite(0x83);
      strdis("Ultrasonic");
      cmdwrite(0xC0);
      strdis("Distance Sensor");
      MSDelay(2000);
          while(1)
          {
              H_byte=0; L_byte=0; F_byte=0;
              TRIG=1;
              TRIG=0;
              TMR1H=0x00;
              TMR1L=0x00;
              while(disp==0);
              disp=0;

              H_byte=CCPR1H;
              L_byte=CCPR1L;
              CCPR1L=0x00; CCPR1H=0x00;
              F_byte=(H_byte * 256);
              F_byte=F_byte + L_byte;
              F_byte=(F_byte * 0.5);
              distance_in_cm=F_byte/58;
              distance_in_inches=F_byte/148;
              cmdwrite(0x01);
              cmdwrite(0x80);
              strdis("Dist.cm:");
              cmdwrite(0x88);
              dis4digit(distance_in_cm);
              cmdwrite(0xC0);
              strdis("Dist.in:");
              cmdwrite(0xC8);
              dis4digit(distance_in_inches);
              MSDelay(6000);
              cmdwrite(0x01);
          }
}

void cmdwrite(unsigned char var1)
{
PD=var1;
RS=0;
RW=0;
E=1;
ms_delay();
E=0;
}
void datawrite(unsigned char var2)
{
PD=var2;
RS=1;
RW=0;
E=1;
ms_delay();
E=0;
}
void strdis(unsigned char *str)
{
        while(*str!='\0')
        {
        datawrite(*str);
        str++;
        }
}
void dis4digit(unsigned int var)
{
     unsigned char thp,hp,up,tp,w,x,y;
     w=var/10;
     x=w/10;
     y=x/10;
     thp=y;
     hp=x%10;
     tp=w%10;
     up=var%10;
     datawrite(thp+48);
     datawrite(hp+48);
     datawrite(tp+48);
     datawrite(up+48);
}
void ms_delay()
{
T1CON = 0x30;
TMR1H=0xC2;
TMR1L=0xF7;
TMR1ON=1;
while(TMR1IF==0);
TMR1ON=0;
TMR1IF=0;
}
/*void msd()
{
T1CON = 0x30;
TMR1H=0xFF;
TMR1L=0xFE;
T1CON.TMR1ON=1;
while(PIR1.TMR1IF==0);
T1CON.TMR1ON=0;
PIR1.TMR1IF=0;
} */
void MSDelay(unsigned int itime)
{
unsigned int i;
unsigned int j;
for(i=0;i<itime;i++)
for(j=0;j<165;j++);
}
void CCP1_ISR()
{
if(rf==0) rising();
else falling();
}
void rising()
{
TMR1ON=1;
rf=1;
CCP1M0=0;
CCP1IF=0;
}
void falling()
{
TMR1ON=0;
disp=1;
rf=0;
CCP1CON=0x00;
CCP1M0=1;
CCP1IF=0;
}
\$\endgroup\$
  • \$\begingroup\$ am using MPLABX \$\endgroup\$ – Kulbir Singh Sep 22 '14 at 6:48
  • 1
    \$\begingroup\$ The compiler doesn't know the key words "code" and "interrupt". Have a look at this Migration Guide (ww1.microchip.com/downloads/en/DeviceDoc/50002184A.pdf). The other warnings I need a clear look at home, but after a first look I think you use wrong pointer types... \$\endgroup\$ – GER_Moki Sep 22 '14 at 7:24
  • \$\begingroup\$ For a start you should be using #include <xc.h> not htc.h or pic.h. Change this, recompile then post the output again. \$\endgroup\$ – David Sep 22 '14 at 7:48
  • \$\begingroup\$ This time i used #include <xc.h> and it build successfully but still with unknown pragma and pointer warnings. The pointer code works perfectly in mikroc. I am new to MPLAB and the other question i want to ask is what exactly xC8, xc16, xc18 and xc32 means. Am sorry if thats a silly question. Please help me i need to learn MPLAB. \$\endgroup\$ – Kulbir Singh Sep 22 '14 at 14:33
  • \$\begingroup\$ I didn't test, but I think this would compile fine on MPLAB IDE if you change the first line to include 16f877a.h instead. However, it's far from recommendable and should only be used if you need a quick fix. \$\endgroup\$ – user17592 Sep 22 '14 at 16:58
2
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Even if you use MPLab IDE, the code you are writing is still C.

xC8, xc16 and xc32 The XC8, XC16 and XC32 are compilers for the PIC processors by Microchip. XC8 are used for 8bit-MCUs, XC16 for 16bit-MCUs and XC32 for 32bit-MCUs. Here you will get a clear overview about the compilers

The C18 was an old compiler for 8bit MCUs. If you just start programming PICs use the XC-equivalent :-)

Pragma warnings

I already showed you the Migration guide. For getting the warning on line 23 away write

void My_HiPrio_Int @ 0x0008 (void)

instead of

#pragma code My_HiPrio_Int=0x0008
void My_HiPrio_Int(void)

Have a clear look at page 34 for this!

The pragma statement on line 36 is not neccessary anymore, when compiling with XC8 instead of C18.

To avoid the warning in line 30 you can write

 void interrupt chk_isr(void)

instead of

 #pragma interrupt chk_isr
 void chk_isr(void)

Page 32 will help you with this ;-)

illegal pointer conversion

You try to send a const-String with the strdis()-function. Write

 void strdis(unsigned char const  *str)

to show the compiler that the pointer values won't be overwritten in the function (hope this works, i don't have XC8 compiler with we, sorry). Otherwise you can make a type conversion when calling strdis(). For example:

 strdis((unsigned char *)"Hello")

But i won't recommend this! Even if you know what you do!

Last in line 83 you write

 F_byte=(F_byte * 0.5);

Instead write the following

 F_byte=(F_byte / 2);

When calculating with float numbers the compiler will do a type conversion by himself. So he converts F_byte to a float and then multiplies with 0.5. float-calculation is much slower than integer-calculation, so avoid this whereever possible.

If you find something like F_byte=(F_byte >> 1); anywhere in the www, you can be sure that every compiler, which is nearly up-to-date will do this code optimisation while compiling.

Complete Code

With XC8 v1.33 this code compiles without any error or warning:

#include<xc.h>

#define TRIG RB7
#define PD PORTD
#define RS RE0
#define RW RE1
#define E RE2

void cmdwrite(unsigned char);
void datawrite(unsigned char);
void strdis(unsigned char const *str);
void MSDelay(unsigned int itime);
void ms_delay();
void dis4digit(unsigned int var);
void CCP1_ISR(void);
void rising(void);
void falling(void);
void interrupt chk_isr();
unsigned char disp = 0;
unsigned char rf = 0;

void interrupt chk_isr(void) {
    if (CCP1IF == 1)
        CCP1_ISR();
}

void main() {
    unsigned long int distance_in_cm;
    unsigned long int distance_in_inches;
    unsigned long int F_byte;
    unsigned char H_byte, L_byte;

    ADCON1 = 0x0F;
    GIE = 1;
    PEIE = 1;
    CCP1IE = 1;
    TRISD = 0;
    TRISE = 0;
    TRISB7 = 0;
    TRISC2 = 1;
    CCP1CON = 0x05;
    T1CON = 0x00;
    CCPR1L = 0x00;
    CCPR1H = 0x00;
    TRIG = 0;
    E = 0;
    cmdwrite(0x01);
    cmdwrite(0x38);
    cmdwrite(0x38);
    cmdwrite(0x38);
    cmdwrite(0x0C);
    cmdwrite(0x83);
    strdis("Ultrasonic");
    cmdwrite(0xC0);
    strdis("Distance Sensor");
    MSDelay(2000);
    while (1) {
        H_byte = 0;
        L_byte = 0;
        F_byte = 0;
        TRIG = 1;
        TRIG = 0;
        TMR1H = 0x00;
        TMR1L = 0x00;
        while (disp == 0);
        disp = 0;

        H_byte = CCPR1H;
        L_byte = CCPR1L;
        CCPR1L = 0x00;
        CCPR1H = 0x00;
        F_byte = (H_byte * 256);
        F_byte = F_byte + L_byte;
        F_byte = (F_byte / 2);
        distance_in_cm = F_byte / 58;
        distance_in_inches = F_byte / 148;
        cmdwrite(0x01);
        cmdwrite(0x80);
        strdis("Dist.cm:");
        cmdwrite(0x88);
        dis4digit(distance_in_cm);
        cmdwrite(0xC0);
        strdis("Dist.in:");
        cmdwrite(0xC8);
        dis4digit(distance_in_inches);
        MSDelay(6000);
        cmdwrite(0x01);
    }
}

void cmdwrite(unsigned char var1) {
    PD = var1;
    RS = 0;
    RW = 0;
    E = 1;
    ms_delay();
    E = 0;
}

void datawrite(unsigned char var2) {
    PD = var2;
    RS = 1;
    RW = 0;
    E = 1;
    ms_delay();
    E = 0;
}

void strdis(unsigned char const *str) {
    while (*str != '\0') {
        datawrite(*str);
        str++;
    }
}

void dis4digit(unsigned int var) {
    unsigned char thp, hp, up, tp, w, x, y;
    w = var / 10;
    x = w / 10;
    y = x / 10;
    thp = y;
    hp = x % 10;
    tp = w % 10;
    up = var % 10;
    datawrite(thp + 48);
    datawrite(hp + 48);
    datawrite(tp + 48);
    datawrite(up + 48);
}

void ms_delay() {
    T1CON = 0x30;
    TMR1H = 0xC2;
    TMR1L = 0xF7;
    TMR1ON = 1;
    while (TMR1IF == 0);
    TMR1ON = 0;
    TMR1IF = 0;
}

void MSDelay(unsigned int itime) {
    unsigned int i;
    unsigned int j;
    for (i = 0; i < itime; i++)
        for (j = 0; j < 165; j++);
}

void CCP1_ISR() {
    if (rf == 0) rising();
    else falling();
}

void rising() {
    TMR1ON = 1;
    rf = 1;
    CCP1M0 = 0;
    CCP1IF = 0;
}

void falling() {
    TMR1ON = 0;
    disp = 1;
    rf = 0;
    CCP1CON = 0x00;
    CCP1M0 = 1;
    CCP1IF = 0;
}

Here's my build log:

make -f nbproject/Makefile-default.mk SUBPROJECTS= .build-conf
make[1]: Entering directory `C:/Users/x.x/VirtualBox VMs/KT/test.X'
make  -f nbproject/Makefile-default.mk dist/default/production/test.X.production.hex
make[2]: Entering directory `C:/Users/x.x/VirtualBox VMs/KT/test.X'
"C:\Program Files (x86)\Microchip\xc8\v1.33\bin\xc8.exe" --pass1  --chip=16F877A -Q -G  --double=24 --float=24 --opt=default,+asm,+asmfile,-speed,+space,-debug --addrqual=ignore --mode=free -P -N255 --warn=0 --asmlist --summary=default,-psect,-class,+mem,-hex,-file --output=default,-inhx032 --runtime=default,+clear,+init,-keep,-no_startup,+osccal,-resetbits,-download,-stackcall,+clib --output=-mcof,+elf:multilocs --stack=compiled:auto:auto "--errformat=%%f:%%l: error: (%%n) %%s" "--warnformat=%%f:%%l: warning: (%%n) %%s" "--msgformat=%%f:%%l: advisory: (%%n) %%s"    -obuild/default/production/main.p1  main.c 
"C:\Program Files (x86)\Microchip\xc8\v1.33\bin\xc8.exe"  --chip=16F877A -G -mdist/default/production/test.X.production.map  --double=24 --float=24 --opt=default,+asm,+asmfile,-speed,+space,-debug --addrqual=ignore --mode=free -P -N255 --warn=0 --asmlist --summary=default,-psect,-class,+mem,-hex,-file --output=default,-inhx032 --runtime=default,+clear,+init,-keep,-no_startup,+osccal,-resetbits,-download,-stackcall,+clib --output=-mcof,+elf:multilocs --stack=compiled:auto:auto "--errformat=%%f:%%l: error: %%s" "--warnformat=%%f:%%l: warning: (%%n) %%s" "--msgformat=%%f:%%l: advisory: (%%n) %%s"     -odist/default/production/test.X.production.elf  build/default/production/main.p1     
Microchip MPLAB XC8 C Compiler (Free Mode) V1.33
Part Support Version: 1.33 (A)
Copyright (C) 2014 Microchip Technology Inc.
License type: Node Configuration

:: warning: (1273) Omniscient Code Generation not available in Free mode

Memory Summary:
    Program space        used   46Ch (  1132) of  2000h words   ( 13.8%)
    Data space           used    33h (    51) of   170h bytes   ( 13.9%)
    EEPROM space         used     0h (     0) of   100h bytes   (  0.0%)
    Data stack space     used     0h (     0) of    60h bytes   (  0.0%)
    Configuration bits   used     0h (     0) of     1h word    (  0.0%)
    ID Location space    used     0h (     0) of     4h bytes   (  0.0%)


Running this compiler in PRO mode, with Omniscient Code Generation enabled,
produces code which is typically 40% smaller than in Free mode.
The MPLAB XC8 PRO compiler output for this code could be 432 words smaller.
See http://microchip.com for more information.

make[2]: Leaving directory `C:/Users/x.x/VirtualBox VMs/KT/test.X'
make[1]: Leaving directory `C:/Users/x.x/VirtualBox VMs/KT/test.X'

BUILD SUCCESSFUL (total time: 1s)
Loading code from C:/Users/x.x/VirtualBox VMs/KT/test.X/dist/default/production/test.X.production.hex...
Loading symbols from C:/Users/x.x/VirtualBox VMs/KT/test.X/dist/default/production/test.X.production.elf...
Loading completed

The errors and warnings you get are not MPLab specific... Consider reading a GOOD book about C programming (for example K&R) and google the errors at first.

|improve this answer|||||
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  • \$\begingroup\$ I truly appreciate your help. I've made changes as you suggested. Now since yesterday am getting two warnings on "CCP1_ISR" function. First warning points to "rising();" while second warning points to "falling();". And two errors on "void rising()" function. Both the errors points to the curly brackets in the function. "Warnings: function declared implicit int" and "Errors: type redeclared and conflicting declarations for variable "rising"". \$\endgroup\$ – Kulbir Singh Sep 23 '14 at 7:31
  • \$\begingroup\$ Are you sure, this is exactly the same code you posted above? \$\endgroup\$ – GER_Moki Sep 23 '14 at 8:44
  • \$\begingroup\$ yes i am sure. this is the same code \$\endgroup\$ – Kulbir Singh Sep 23 '14 at 9:57
  • \$\begingroup\$ ok now there are no warnings and errors. I've made few changes in the interrupt function tell me if am wrong. void chk_isr(void); unsigned char disp=0,rf=0; void chk_isr(void) { if(CCP1IF==1) CCP1_ISR(); } void interrupt Hi_Prio_Int(void) @ 0x0008 { chk_isr(); } but unfortunately the code is not working on kit. \$\endgroup\$ – Kulbir Singh Sep 23 '14 at 12:58
  • \$\begingroup\$ I don't have this PIC here, so can't give it a try. I will have a look later :) \$\endgroup\$ – GER_Moki Sep 23 '14 at 13:16

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