Need Help in C question

[Lion]

Hello everyone,

I am using PIC 16F877 and CCS 3.222 version, MPLAB V8.1 .

My question is that I am using UV tron flame detector.

When the sensor detect the fire, it will output_high.

I am using UV tron and Temperature sensor at the same time.

[Ttemah]

Probably.
Only though, if your 'temp' value, is directly reading in degrees. Most sensors, won't...

Best Wishes

[Lion]

Hello everyone,

Maybe I need to describe problem clearly.

I know that I can use " while(! input(PIN_D5)) " to wait for the PIN_D5 go high or use "while(input(PIN_D5))" to wait for the PIN_D5 go low.

My question is that may I use "if" to do the same thing? I mean that I have two conditions for " if " loop. One is " Temp>30 " and the other one is UV sensor output is high.

May I use " if (Temp> 30 && input(PIN_D5))" ? So far, I tried many ways but it can not get in the " if loop " Sometimes when Temp> 30 but PIN_D5 does not high. The code get in the loop.

Do I do something wrong? Could you give me some suggestion?




I really really appreaciate it.

[apcaye]

I think there is nothing wrong in your code, it's supposed to work. However, I would suggest that you force both conditions to be true inside an infinite loop, as below:

[Lion]

Hello everyone,

apcaye!! Thank you for your reply.

Following is my code. I think that I can not add a "while(1)" in there in my situation.

I am confused. I use many "goto" command in my code. Does it damage the code structure?

In Problem 1, I try to check two conditions but it can not get in the "Problme 1" code in the beginning but I tries many method. Now it always get in the "Problem One" code but the flame detector do not detect the fire (if detect the fire, flame detector will output high). I do not understand why the code do not consider the condition?

My second question:
May I use the condition like (input(PIN_A2)!=0) or (input(PIN_A2)>1)
or (input(PIN_A2)==0)

The syntax is correct or not? If the PIN_A2 is used to check the flame detector output is high or low.

I really need someone help me to figure out.
Any help will be really really apprecitated.
Thank you so much

[apcaye]

You're welcome, Lion. If you can't add a while(1) loop in your code, create another test program with only this simple loop. One way to try to solve a problem is to isolate it, as in this case.

Have you simulated your code, step-by-step? It could help a lot. In MPLAB IDE's Stimulus window, you can simulate an I/O pin going high or low, which is fine to test your "if" statements.

Yes, using "goto" is not a good programming practice, you should avoid them. Try to rewrite your code, replace them with function calls, for example.

"input(PIN_A2)>1" is not a valid test, because the "input" function return a boolean value. The other tests you mentioned are Ok.

Hope that helps! Regards,
Adriano.

[apcaye]

And one more thing: you should initialize your I/O pins, telling the compiler what pins are input and what pins are output. By default, all pins are input. I use to write directly to TRISx registers to do that, but there should be a function for that if you prefer.

Regards,
Adriano.