serial port and timer

Do you know how to use the C167's serial port?

Do you know how to use a timer on the C167?

No unfortunately no. I have never used a Microcontroller. This problem has been assigned me and I doesn't know whether to resolve it. Could you help me?

Have you ever done any programming at all?

Here is an extremely basic program that does what you ask. Perhaps this helps to get you started as you will surely need to modify it.

#include "c167cs.h"
#include "intrins.h"

void GPT1_viTmr3(void) interrupt 0x23 {
  S0TBUF = '0';
  S0TBUF = '1';  /* allowed since the register is double buffered */
  P2 ^= 0x0001;  /* toggle P2.0 */
}

void main(void) {
  /* setup the serial port */
  S0BG  = 0x0040; /* 9.600 kbaud @ 20 MHz clock */
  S0CON = 0x0011; /* format: 8-N-1 */

  /* P3.10 is used for TxD and P3.11 is used for RxD */
  _bfld_( P3,0x0C00,0x0400);    /**/
  _bfld_(DP3,0x0C00,0x0400);    /* set data direction */

  S0CON |= 0x8000; /* enable baud rate */

  /* use GPT1 for the 1 second time base */
  T3CON = 0x0087;  /* clock tick is 51.2 usec, count down */
  T3    = 0x4C4B;  /* 1 second load value */

  T2CON = 0x0027;  /* t2 reloads T3 on the interrupt */
  T2    = 0x4C4B;

  T3IC  = 0x004B;  /* set up the interrupt level and enable it */
  T3R   = 1;       /* start timer 3 running */

  DP2   = 1;       /* toggle P2.0 every second */

  IEN   = 1;       /* globally enable interrupts */

  for(;;){};
}

Hope this helps.
-Chris

Thanks a lot. Monday I will try it to the university and I will make you know. Thanks still for the help!

The code works very well and visualizes me "01" every second. As I do for making me visualize before "0", after a second "1", after another second "0", after another second "1" ..... etc. Must I put another timer? What must I change in the list? Thanks as for the help.

If I were to do it, I could imagine that you would use a counter (volatile variable) that checks if it is even or odd. If even you send a '0' and when it is odd you send a '1'. This logic (code) would be placed in the interrupt that already exists for the one second.

"...I will try it to the university..."

Is this a homework assignment that you should be doing yourself...?

In practice I must bring my thesis stand-alone using this microcontroller and the prof has told me to begin with this application.

The have inserted to "if" in such way to make me stamp, alternatively, "0" and "1" to distance of to second. The tails is the following:

#include "c167cs.h"
#include "intrins.h"

int a;
a=0;

void GPT1_viTmr3(void) interrupt 0x23 {

  if(a=0)
     {S0TBUF = '0';
      a=1;}
  else
     {S0TBUF = '1';
      a=0;}

  P2 ^= 0x0001;  /* toggle P2.0 */
}

void main(void) {
  /* setup the serial port */
  S0BG  = 0x0040; /* 9.600 kbaud @ 20 MHz clock */
  S0CON = 0x0011; /* format: 8-N-1 */

  /* P3.10 is used for TxD and P3.11 is used for RxD */
  _bfld_( P3,0x0C00,0x0400);    /**/
  _bfld_(DP3,0x0C00,0x0400);    /* set data direction */

  S0CON |= 0x8000; /* enable baud rate */

  /* use GPT1 for the 1 second time base */
  T3CON = 0x0087;  /* clock tick is 51.2 usec, count down */
  T3    = 0x4C4B;  /* 1 second load value */

  T2CON = 0x0027;  /* t2 reloads T3 on the interrupt */
  T2    = 0x4C4B;

  T3IC  = 0x004B;  /* set up the interrupt level and enable it */
  T3R   = 1;       /* start timer 3 running */

  DP2   = 1;       /* toggle P2.0 every second */

  IEN   = 1;       /* globally enable interrupts */

  for(;;){};
}

The problem is that it stamps only me "1" every second. would someone know me to explain because? Thanks so much.

if (a = 0) { ... }

is an assignment, i.e. it doesn't matter what value a had before your test. You must use == to compare, i.e.

if (a == 0) { ... }

Or reverse the two parts of the if/else and drop the explicit comparison:

if (a) {
    S0TBUF = '1';
    a = 0;
} else {
    S0TBUF = '0';
    a = 1;
}

You can also remove the if statement totally:

S0TBUF = '0' + (a++ & 1);

This extracts the odd/even bit of a, and continuously increments a.

The problem is that I want to stamp "0" then after a second "1", after another second "0", after another second "1" .... ect.With the instruction:

S0TBUF = '0' + (a++ & 1);

does it increase the value progressively?

"does it increase the value progressively?"

Per's post clearly described what it does - read it again, carefully...

As I already mentioned: "This extracts the odd/even bit of a". This means you will alternate between adding 0 and 1 to your printout, i.e. the printout will be 0101010101010101010101...

By the way - why do you want such a printout? It isn't exactly meaningful. You already have a toggling pin. Why emit trace output whenever you toggle the pin? Doesn't your pin toggling work?

Another thing: Why do you declare a as int? You are programming an 8-bit processor and int is in this case a 16-bit data type. Using a data type larger than the native register size is not recommended unless you need the range. In this case, your code only makes use of the values 0 and 1. You could use a 1-byte variable, or you could even modify your code to use a 1-bit variable.