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RatFink
Joined: 01 May 2004
Posts: 49
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| Another small problem I could use some help with |
 Posted: Mon May 03, 2004 12:45 am |
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Looking at this
| Code: | else if (PB_Plastic == 0)
{
Plastic = 1; |
How can I make it so that when "Plastic = 1;" I get a count down timer that when it reaches zero in makes "Plastic = 0;" and prints the count down as it happens.
I've tried just asigning a memory address and loading it with a value and then having it decrement the value every 60,000 mS, printing that value, and then set Plastic = 0 when that address reaches zero.
My problem is that while it loads the address, it doesn't decrament. I also can't get it to print the value in that address.
Could somebody point me in the right direction please?[/b]
Last edited by RatFink on Mon May 03, 2004 11:35 am; edited 1 time in total |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Mon May 03, 2004 5:15 am |
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Why are you assigning a memory address to a variable? The nice thing about using a compiler is that the compiler can handle that low level stuff for you.
I would suggest to use a global variable and I guess your problems will disappear. |
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rwyoung
Joined: 12 Nov 2003
Posts: 563
Location: Lawrence, KS USA
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| Posted: Mon May 03, 2004 7:52 am |
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For you countdown timer you should probably use the PIC's timer2.
Set up the timer to generate an interrupt once per 1ms or 60ms or some even multiple of the 60,000ms you desire.
In the timer interrupt service routine you would have a 16-bit unsigned int (assuming you set the interval to get 1ms resolution, the variable would need to count to 60,000). At each interrupt you increment the counter and when it reaches 60,000 you change the value of your global variable Plastic back to zero.
But, do not enable the timer interrupt yet. You would clear its counter and enable just before your Plastic=1 expression.
As far as printing the time, DON'T DO THAT INSIDE THE INTERRUPT SERVICE ROUTINE. This is important, so I'll say it again, DON'T USE PRINTF INSIDE THE INTERRUPT SERVICE ROUTINE. ISRs should be small and fast. printf is neither small nor fast.
If you must display the count value, do it in your main()'s infinite loop (remember I mentioned using a while(1){} structure). If your loop takes long enough to get through that you can guarantee the timer would have changed, just printf each pass through the loop. Otherwise you can monitor the timer's count variable for change and only print if it has changed.
Keep in mind that the printf statement will take a fairly long time to execute, probably longer than 1ms.
Probably much more information than you wanted, so I'm going to give you even more data to digest...
Examples of timer2 interrupt service routines are found in the CCS example programs. Check the help file for a list of example programs and descriptions. Also this board has a very good search feature. You will get lots and lots of hits if you search on "timer2" or "timer2 setup". And finally, read the Microchip datasheet on the operation of the timers. I think you mentioned before you were using a 16F part so you would also benefit from reading the mid-range reference manual.
You have 30 minutes to complete the exercise, begin! 
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month! |
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Ttelmah
Guest
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| Re: Another small problem I could use some help with |
| Posted: Mon May 03, 2004 8:32 am |
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| RatFink wrote: | Looking at this
| Code: | else if (PB_Plastic = 0)
{
Plastic = 1; |
How can I make it so that when "Plastic = 1;" I get a count down timer that when it reaches zero in makes "Plastic = 0;" and prints the count down as it happens.
I've tried just asigning a memory address and loading it with a value and then having it decrement the value every 60,000 mS, printing that value, and then set Plastic = 0 when that address reaches zero.
My problem is that while it loads the address, it doesn't decrament. I also can't get it to print the value in that address.
Could somebody point me in the right direction please?[/b] |
Note also, that as written, the code sets 'PB_Plastic', to zero, which will evaluate as 'false' all the time...
Best Wishes |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Mon May 03, 2004 9:26 am |
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From a previous post:
| Quote: |
Posted: Sun May 02, 2004 2:31 pm
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Thank you guys, I can't believe I misses the "=" instead of "==", I was tearing my hair out wondering why it wouldn't work.
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Hi RatFink,
You get a choice:
1) study/practice a little more "C"
2) or you will get becoming baldness... 
Hope not being offensive.
Humberto |
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RatFink
Joined: 01 May 2004
Posts: 49
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| Posted: Mon May 03, 2004 10:01 am |
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| Humberto wrote: | From a previous post:
| Quote: |
Posted: Sun May 02, 2004 2:31 pm
--------------------------------------------------------------------------------
Thank you guys, I can't believe I misses the "=" instead of "==", I was tearing my hair out wondering why it wouldn't work.
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Hi RatFink,
You get a choice:
1) study/practice a little more "C"
2) or you will get becoming baldness...
Hope not being offensive.
Humberto |
Nope not offensive, I've taken on this project thinking that the few things I wanted to do were simple, and I still think they are, but I just lack the experience to see small mistakes and simple paths to do things. getting ponted in the right direction here helps.
I've tried looking through all the examples, and I've searched through the forum but it just got me more confused because I wasn't even sure what exactly I was looking for, but now I have an idea what it is I need.
Thanks to all that showed me what I need to do and what I was doing wrong, I'll go look up all this Timer2 stuff. |
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AK
Joined: 20 Apr 2004
Posts: 33
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| Posted: Mon May 03, 2004 11:14 am |
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The else if statement should be:
| Code: | else if (PB_Plastic == 0)
{
Plastic = 1; |
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RatFink
Joined: 01 May 2004
Posts: 49
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| Posted: Mon May 03, 2004 11:34 am |
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| AK wrote: | The else if statement should be:
| Code: | else if (PB_Plastic == 0)
{
Plastic = 1; |
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Yup, I got that in my other thread, when I posted this thread I just copy/pasted the code from the other thread without the fix. I just fixed it in my first post so people would quit seeing how stupid I am |
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rwyoung
Joined: 12 Nov 2003
Posts: 563
Location: Lawrence, KS USA
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| Posted: Tue May 04, 2004 8:27 am |
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Ratfink -
Keep trying. I know I have lots of scars from doing stupid things when I started learning C and again later when I started working with microcontrollers. Make mistakes, just learn from them so you can make new and better mistakes later.
I can only imagine how scarred and disfigured PCM Programmer and RJHamlet (and Neutone and dozens of others on this forum) are with their deep understaning of C & ASM on the PIC. I'm sure it came at a heavy price. 
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month! |
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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Posted: Tue May 04, 2004 5:41 pm |
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Rob is right on the spot.
"There is only one thing more painful than learning from experience and that is not learning from experience."
Archibald McLeish |
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RatFink
Joined: 01 May 2004
Posts: 49
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| Posted: Wed May 05, 2004 1:00 am |
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Thanks guys, I got it to work and it was much easier than I thought it would be, it works fine but you guys tell me how ugly this is;
| Code: | else if (PB_Plastic == 0)
{
PORTD =0x13;
}
/* Timer Function "Plastic" */
if (Timed1 == 1) /*I assigned this earlier "#bit Timed1 = PORTD.4"*/
{
int T_Plastic = 20;
while (T_Plastic > 0)
{
printf("%d\n", T_Plastic);
--T_Plastic;
delay_ms (60000);
}
if (T_Plastic == 0)
{
PORTD =0x0C;
}
}
/* End Timer Function "Plastic" */ |
Now when the button is pressed, the heat coil and fan activates and the time is displayed. it then counts down and 20 minutes later the heat coil turns off, the fan kicks into high speed and the vent baffle opens.
Now I have to hook up an LCD and make it work |
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rwyoung
Joined: 12 Nov 2003
Posts: 563
Location: Lawrence, KS USA
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| Posted: Wed May 05, 2004 7:56 am |
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This portion will prevent you from servicing any button presses unless you do them as interrupts. And for that matter, the PIC can't be doing anything else unless it is an interrupt service routine. It is also going to have some accuracy problems, I predict it will tend to run a bit on the long side if for no other reason than the printf statement takes some finite amount of time so your delay is really (60,000 + time-printf + time-to-decrement + loop-overhead) * T_Plastic
| Code: | while (T_Plastic > 0)
{
printf("%d\n", T_Plastic);
--T_Plastic;
delay_ms (60000);
}
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But, if it works and does what you need with the accuracy you need then fine. You have plenty of things to learn how to do and keep you busy.
You mentioned an LCD, if you are planning on a "standard" character based LCD with driver, the example programs supplied with the compiler are very good. You may need to re-arrange your port assignments so you can use the example code though. I think it is designed for PORTB and uses 6 of the 8 available lines. d
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month! |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Wed May 05, 2004 10:07 am |
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Hi RatFink,
I�m feeling a kind of embarrassment regarding my previous comments, it wasnt
my intention to be ofensive in any way, just to steal a smile...
I want to compensate such fault. Feel free to drop me a line at
my email if you want some help with your project regarding the LCD upgrade.
Sincerely,
Humberto |
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RatFink
Joined: 01 May 2004
Posts: 49
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| Posted: Wed May 05, 2004 11:24 am |
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| rwyoung wrote: | | But, if it works and does what you need with the accuracy you need then fine. You have plenty of things to learn how to do and keep you busy. |
Running a few seconds off will not be a problem here, and according to my watch it seems to be pretty dang close to 20 minutes, but I did think about that having noticed you mentioned it in a previous post. This just worked out easiest for me at this time, I may make some changes if I have time later. It just makes me happy know that it does what it's supposed to.
| rwyoung wrote: | | You mentioned an LCD, if you are planning on a "standard" character based LCD with driver, the example programs supplied with the compiler are very good. You may need to re-arrange your port assignments so you can use the example code though. I think it is designed for PORTB and uses 6 of the 8 available lines. d |
I know about the conflict between my inputs on PORTB and the LCD driver, but for some reason I'm having any other port just work, they all have some wierdness that requires extra hardware or something. I will have to deal with it though, it would be easier for me to change my 4 inputs than to try messing around with the default LCD driver.
| Humberto wrote: | Hi RatFink,
I�m feeling a kind of embarrassment regarding my previous comments, it wasnt
my intention to be ofensive in any way, just to steal a smile...
I want to compensate such fault. Feel free to drop me a line at
my email if you want some help with your project regarding the LCD upgrade.
Sincerely,
Humberto |
Don't worry, I took no offense to your post, and saw it as you just goofing around, but I may take you up on your offer of help w/ the LCD if I have trouble. Thank you for the offer. |
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