Hi everybody.

First of all, I have zero programing experince in any language.
So this may be a stupid question.

After reading and researching for a feew weeks I have decided to learn
c and starded with pic16f84a,
I found some code on the internet and tried to compile it but I get compiler errors-

This is the code


" #include <16F84A.h>
#use delay(clock=10000000)
#fuses NOWDT,HS, NOPUT, NOPROTECT
#use rs232(baud=1200,parity=N,xmit=PIN_A2,rcv=PIN_A3,bits=9)

void clockwait(void);

void main()
{
unsigned char byt; // Holds each byte received

setup_counters(RTCC_INTERNAL,RTCC_DIV_1);

while(1) // Loop forever...
{
byt=0; // Starting a new data frame

clockwait(); // Ignore start bit
for(t=0;t<8;t++) // Grab eight bits of data... LINE 21
{
clockwait();
byt|=input(PIN_A0)<<t;
}
clockwait(); // Ignore parity bit
clockwait(); // Ignore stop bit

putc(byt); // Send byte to the transmitter

} // ... rinse and repeat
}

clockwait()
{
// Waits for the next clock cycle...
while(!input(PIN_A1)); // Wait for clock to go HI
while(input(PIN_A1)); // Wait for clock to go LO
}


Thes are the errors I'm getting

"*** Error 12 "main.c" Line 21(11,12): Undefined identifier t
*** Error 12 "main.c" Line 21(16,17): Undefined identifier t
*** Error 12 "main.c" Line 21(21,22): Undefined identifier t
*** Error 12 "main.c" Line 24(33,34): Undefined identifier t
4 Errors, 1 Warnings.
Halting build on first failure as requested.
BUILD FAILED: Wed Jul 09 22:50:02 2008"


After reading about this for a feew days I know that i need to declare
a variable "t" , but i can't get the exact hang of it .

any help wuld be highly appreciated.

P.S I'm using ccs pcm and Mplab IDE ver 8.10


cheers

 

As t is used as a counter with a range of [0..8] you might try

unsigned char t ;

if you decalre it inside the function then it is a local variable, and if you declare it outside the function then it is global.

 

As t is used as a counter with a range of [0..8] you might try

unsigned char t ;

if you decalre it inside the function then it is a local variable, and if you declare it outside the function then it is global.

Thank you so much for the answer, now i know that I have bin close all the time, but I still don't know where exactly put code

This is how i tried it

"
----code snip---

while(1) // Loop forever...
{

byt=0; // Starting a new data frame

clockwait(); // Ignore start bit


unsigned char t ; YOUR CODE HERE


for(t=0; t<8; t++) // Grab eight bits of data...
{
clockwait();
byt|=input(PIN_A0)<<t;

----code snip----
"


These are the errors I got

"Executing: "C:\Program Files\PICC\Ccsc.exe" +FM "main.c" +DF +LN +T +A +M +Z +Y=9 +EA
>>> Warning 203 "main.c" Line 15(1,1): Condition always TRUE
*** Error 51 "main.c" Line 20(7,15): A numeric expression must appear here
*** Error 12 "main.c" Line 21(11,12): Undefined identifier t
*** Error 12 "main.c" Line 21(16,17): Undefined identifier t
*** Error 12 "main.c" Line 21(21,22): Undefined identifier t
*** Error 12 "main.c" Line 24(33,34): Undefined identifier t
5 Errors, 1 Warnings.
Halting build on first failure as requested.
BUILD FAILED: Thu Jul 10 00:34:40 2008"

 

Is "YOUR CODE HERE" in the actual source is that just an annotation you made after posting here?

I'd also lose the space between t and the semicolon. I don't think that's the problem (at least not with gcc) but it's just bad form.

I'd recommend reading a book on C or some tutorials on the internet ("c tutorial" is a good google query).

 

Is "YOUR CODE HERE" in the actual source is that just an annotation you made after posting here?

I'd also lose the space between t and the semicolon. I don't think that's the problem (at least not with gcc) but it's just bad form.

I'd recommend reading a book on C or some tutorials on the internet ("c tutorial" is a good google query).

"YOUR CODE HERE"
means that I have used the suggested declaration from Papabravo "unsigned char t ;"

My question is where tu put it ? (look at my previous post where I put it )

After I put it in the code I still get this error

"*** Error 51 "main.c" Line 20(7,15): A numeric expression must appear here
*** Error 12 "main.c" Line 21(11,12): Undefined identifier t"

.

 

Ahh, I think I know what the problem is. Move the declaration to the line under "unsigned char byt;" and see if that fixes the problem.

 

Ahh, I think I know what the problem is. Move the declaration to the line under "unsigned char byt;" and see if that fixes the problem.

Yes that is the problem , if not c++ the variables must be declared at the start of the program
like this;

" ----code snip----

void clockwait(void);

void main()

{
unsigned char byt; // Holds each byte received
unsigned char t; // declaration of variable t

----code snip---
"
And also in my original code I declared my function like this

"void clockwait(void);"
and defined it like this
"clockwait()" But it should be like the declaration "void clockwait(void)"

Now the firmware is compiling, I only get this warning
"Warning 202 "main.c" Line 4(5,8): Variable never used: rs232_errors"
But I'm assuming that this is because the receiving end is not conected


thank you very much for all your answers