help needed with setting prescaller for ATmega 32

[joephie]

[HELP] precise 1 second

can anyone help me calculating the prescale for ATmega 32 on Timer1 with crystal 11.0592 MHz. I'm using BASCOM but i don't know what is the prescale to make precise 1 second.

thank you

 

[bosparra]

Re: [HELP] precise 1 second

Set the prescaler to 1024 and keep a 16bit counter in the interrupt routine to count to 10800(0x2a30), which will be 1 second exactly.

 

[Tahmid]

[HELP] precise 1 second

Yes do what bosparra said.
Use the compare module to count upto 10800 and then clear timer on compare (CTC) and generate interrupt on compare match.

 

[joephie]

Re: [HELP] precise 1 second

i'll give it a try guys.. but i have another problem on enabling the crystal. could anyone help setting up the fuse bit... wich part i should select? ? [CKSEL SUT CKOPT]

 

[Tahmid]

[HELP] precise 1 second

Set the fuse bits as:
CKOPT: 0(PROGRAMMED)
BOOTRST: 1(UNPROGRAMMED)
CKSEL3: 1(UNPROGRAMMED)
CKSEL2: 1(UNPROGRAMMED)
CKSEL1: 1(UNPROGRAMMED)
CKSEL0: 1(UNPROGRAMMED)
SUT1: 0(PROGRAMMED)
SUT0: 1(UNPROGRAMMED)
Hope this helped.
Tahmid.

 

[joephie]

Re: [HELP] precise 1 second

thank you very much for the help... but now im waiting the electricyti, it has been black out since yesterday ....oh my

 

[Aya2002]

Re: [HELP] precise 1 second

thank you very much for the help... but now im waiting the electricyti, it has been black out since yesterday ....oh my

are you from Iraq

 

[joephie]

this is my code

$regfile = "m32def.dat"
$crystal = 11059200

Config Timer1 = Counter , Edge = Falling , Prescale = 1024
Config Lcd = 16 * 2
Config Lcdpin = Pin , Db4 = Porta.2 , Db5 = Porta.3 , Db6 = Porta.4 , Db7 = Porta.5 , E = Porta.1 , Rs = Porta.0
Cursor Off

Stop Counter1
Dim Speed As Long
Dim Speedo As Long

Cls
Do
Counter1 = 0
Start Counter1
Waitms 1000
Stop Counter1
Speed = Counter1
Speed = Speed * 1000
Speedo = Speed / 2
Locate 1 , 1
Lcd "pulse: " ; Speedo
Lowerline
Lcd "Rotation perminute"
Waitms 250

Loop

End

how would i know if my sistem is already running at precise 1 second.....

 

[Tahmid]

Hi,
That code seems to be written in BASCOM, am I right?
I use mikroBASIC and the codes look quite different. So I can't help you.

 

[joephie]

ouh, is there anyone can help....its been a headache to select the prescaler