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vic481
Joined: 02 Dec 2010
Posts: 2
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| help with array send as argument |
 Posted: Thu Dec 02, 2010 2:23 am |
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Hi, all! I'm trying make pwm sound:
| Code: |
void snd(int8 how_many_times,int8 freq_val[5])
{
int8 i;
for(i=0;i<how_many_times;i++)
{
setup_timer_2(T2_DIV_BY_4,freq_val[i],1);
set_pwm1_duty(512);
setup_ccp1(CCP_PWM);
delay_ms(90);
}
setup_ccp1(CCP_off);
}
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If I call this procedure (example for one beep)
| Code: |
snd(1,(184,0,0,0,0));
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only last argument (last 0) is sent to procedure (I see it in .lst file).
What I'm doing wrong? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Thu Dec 02, 2010 5:01 am |
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(184,0,0,0,0), is not an array. It is a mathematical statement, which evaluates each element in turn, and returns the last value in the list. So, '0'. Basic C....
In C, an 'array', is a pointer _to_ a block of values in memory. So you need to pre-declare the array, and hand it's address to the function.
So:
int8 vals[] = {184,0,0,0,0};
snd(1,vals);
Note multiple things:
1) the squirly brackets, not round brackets for the initialisation.
2) You are handing the 'address' of the list to the function, so: &vals[0], which is the address of the first element. However 'C' has a shortcut, which says if you use the 'name' of an array, without a subscript, to automatically assume you want the address. So &vals[0] gives the same address as vals on it's own.
Best Wishes |
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vic481
Joined: 02 Dec 2010
Posts: 2
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| Posted: Thu Dec 02, 2010 12:51 pm |
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| Tnx for reply and explanation. |
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