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sonicfire
Joined: 11 Feb 2007
Posts: 19
Location: Cedar Rapids
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| problems with int16 or methods |
 Posted: Tue Mar 06, 2007 12:24 pm |
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Right now, I'm drawing up an outline for my dc motor control. I was trying to compile this preliminary program, but I get error messages that say "A numeric expression must appear here" for all the lines that say int16. Does this have something to do with the way I wrote the methods (my programming skills are rusty). Thanks for your help. Here's the code:
| Code: | #include <16F877.h>
#device adc=10
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=10000000)
void check_reset() {
int reset_value = 0;
while (reset_value==0) {
reset_value = input(PIN_B1); //delays circuit until user resets circuit (emits high signal to pin B1
}
}
int check_current() {
set_adc_channel( 0 );
int16 current_value;
current_value = (read_adc()*512)/1024;
int overload;
if (current_value > 5) //NOT SURE WHAT THIS VALUE WILL BE YET, BUT 5 is probably a good guess
overload = 1;
else
overload = 0;
return overload;
}
int check_speed() {
return 0; //not sure how to handle this just yet...
}
void compare_with_user() {
int16 value1;
int16 value2;
value1=(read_adc()*512)/1024; //note, adc_channel should already be set to 0 from check_current method!
delay_us( 10 ); //10uS delay is necessary for proper ADC reading.
value2=(read_adc()*512)/1024;
//COMPARISON GOES HERE...
set_pwm1_duty(value1);
/* This sets the time the pulse is high each cycle.
The high time will be:
if value is LONG INT: value*(1/clock)*t2div
if value is INT: value*4*(1/clock)*t2div
for example a value of 30 and t2div of 1 the high time 12uS
A value too high or too low will prevent the output from changing.
*/
}
void main() {
setup_ccp1(CCP_PWM); // Configure CCP1 as a PWM
setup_timer_2(T2_DIV_BY_1, 24, 1); //output at 50KHz
//Period = (1/clock)*4*t2div*(period+1)
setup_port_a(ALL_ANALOG);
setup_adc(adc_clock_internal);
int shutdown1;
int shutdown2;
while( TRUE ) {
shutdown1 = check_current(); //returns 0 if okay and 1 if overloaded
shutdown2 = check_speed(); //returns 0 if okay and 1 if it's too fast
if ( (shutdown1==0)&&(shutdown2==0) )
compare_with_user();
else {
set_pwm1_duty(0);
check_reset();
}
}
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Mar 06, 2007 12:33 pm |
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All local variables must be declared at the start of the function,
before any code. |
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sonicfire
Joined: 11 Feb 2007
Posts: 19
Location: Cedar Rapids
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| Posted: Tue Mar 06, 2007 12:44 pm |
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| That did the trick! Many thanks... |
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rwyoung
Joined: 12 Nov 2003
Posts: 563
Location: Lawrence, KS USA
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| Posted: Tue Mar 06, 2007 1:55 pm |
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| PCM programmer wrote: | All local variables must be declared at the start of the function,
before any code. |
sonicfire - get a copy of Kernighan and Richie's "C Lanugage" 2nd edition. In ANSI C (and in CCS's decidedly non-ANSI C) you MUST complete all declarations prior to starting code in the body of a function.
C++ however relaxed that requirement.
_________________
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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