Question

I am trying to execute some commands using USART communication and reading some values using ATmega32-A. have a look at my code . My problem is i am trying to add some cases (nested switch case) but i am not getting what i want. I hope i am giving all most all information required to solve my problem.

void uniCom(void) {
switch (Command) {
/* ... */
case (muxsel):
  printf(muxselection);
  switch (c) {
    case 1:
      printf("this is mux chaneel1");
      DDRB = 0b10111111;
      PORTB = 0b00000000;
      printf("adc Value", ReadAdc());
      Command = 0;
      break;
    case 2:
      /*-------------------*/
      break;
  }
  Command = 0;
break;
/* ... */
default:
    Command = 0;
    break;
}

}
The problem is undefined c. And I don’t see any declaration of muxselection, maybe missing “” ? Now the second approach.

void selcase(void) {
unsigned char c;
printf("muxselection");
while (rx_counter0) {
 c = getchar();
switch (c) {
  case 1:
    printf("this is mux chaneel1");
    DDRB = 0b10111111;
    PORTB = 0b00000000;
    printf("adc Value", ReadAdc());
    Command = 0;
    break;
  case 2:
    /*-------------------*/
    break;
}
}
}
void uniCom(void) {
switch (Command) {
/* ... */
case (muxsel):
  printf(muxselection);
  selcase();
  Command = 0;
  break;
/* ... */
default:
    Command = 0;
    break;
}
}

My problem is i am executing all the commands as i declared but i want to select some more cases in one of the main switch case command “muxsel”. for that i wrote nested switch case. if i select “muxsel” command on hyperteminal then it is printing like “muxselection” then if i enter 1 to select “case ‘1’”in second switch, nothing is printing. it is printing “command not found”. what is the problem. I want execute nested switch but i am not able to do that using above code I have tried like this also.

void selcase(void) {
         unsigned char c;
         printf("muxselection");
         while (rx_counter0) {
         c = getchar();

         switch (c) {
                  case '1':
                    printf("this is mux chaneel1");
                    DDRB = 0b10111111;
                    PORTB = 0b00000000;
                    printf("adc Value", ReadAdc());
                    c= 0;
                    break;
                  case '2':
                  /*-------------------*/
                  break;
                 default;
                  break;
               }
            }
          }

creating one function for nested switch case and calling in main switch case as shown below.

  void uniCom(void) {
      switch (Command) {
                 /* ... */
                   case (muxsel):
                          printf(muxselection);
                          selcase();
                          Command = 0;
                          break;
                     /* ... */
                     default:
                       Command = 0;
                       break;
         }
       }

this way also not working please suggest me how to overcome this problem. i want to select one of the command in main switch case such as “muxsel” after that i have select mux channels using case statement. any help appreciated.

Thanks in advance.

I have solved this problem.

Answer 1

OK… the code isn’t terribly clear, but I think I see your problem.
You tried to modify the code like this:

case (muxsel):
 printf(muxselection);
  switch (c) {
     case 1:
         printf("this is mux chaneel1");
         DDRB = 0b10111111;
         PORTB = 0b00000000;
         printf("adc Value", ReadAdc());
         Command = 0;
         break;
     case 2: 

First, you don’t have c declared in the scope of the uniCom() function. So that would not compile. Because you didn’t give full code I assume you know that and probably really did something like this:

void uniCom(void) {

    unsigned char c;
    c = getchar();  

    switch (Command) {
      case (no_com):
          Command = 0;
    ....
      case (muxsel):
          printf("muxselection\n"); //Need quotes here and maybe a \n?
          switch (c) {
             case 1:
              ...

Which leads to the next problem. You’re asking for a char c but your cases are built on an int. For example, if the user enters 3, what you’re getting is the character ‘3’ or the int 51. Check the ASCII Table

So your cases are for start of header (SOH), start of text (STX), etc right now… that’s not going to work the way you wanted it to. You need to either do this:

          switch (c) {
             case 51:     // This is ASCII '1'
              ...
              break;
             case 52:     // This is ASCII '2'

Or do this:

          switch (c) {
             case '1':
              ...
              break;
             case '2':

Since you didn’t give your input, or how c was defined, I could be wrong… but I’m going to wager that’s your problem. By the way, make sure you have a default case at the end with a message like “bad input”, it makes this type of thing easier to catch.

EDIT:
Modify the code as follows and share the result:

void runCom(void){
      unsigned char c;
      c = getchar();
      printf("%c %d\n", c, c);   //<-- add this line here
      switch(Command){ 

and

void selcase(void) {
    unsigned char c;
    printf("muxselection");
    while (rx_counter0) {
        c = getchar();
        printf("%c %d\n", c, c); //<-- and this line here
        switch (c) {