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young
Joined: 24 Jun 2004
Posts: 285
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| getc() problem |
 Posted: Wed Oct 13, 2004 1:38 pm |
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I have made a small program
| Code: |
#if defined(__PCM__)
#include <16F819.h>
#fuses XT,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, parity=N, xmit=PIN_B7, rcv=PIN_B6, INVERT)
#include <math.h>
void main()
{
int8 duty,i;
char st=' ';
int val1,val2,val3;
float Total;
int1 incr_decr;
int mode; //lighting condition grabbing set
// setup_comparator(NC_NC_NC_NC);
setup_port_a(AN0_AN1_AN3);
setup_adc( ADC_CLOCK_INTERNAL );
set_tris_b(0b10111011); //set ccp1 pin as low as output ccp1 pin is b2
setup_ccp1(CCP_PWM); // Configure CCP1 as a PWM
setup_timer_2(T2_DIV_BY_1, 255, 1);
duty=50;
set_pwm1_duty(duty);
delay_ms(10);
incr_decr=1;
while(1)
{
while(getc()=='a')
{
set_pwm1_duty(0);
delay_ms(100);
for(i=0;i<256;i++)
{
set_pwm1_duty(i);
delay_ms(50);
set_adc_channel( 0 );
delay_us(100);
val1 = Read_ADC();
set_adc_channel( 1 );
delay_us(100);
val2 = Read_ADC();
set_adc_channel( 3 );
delay_us(100);
val3 = Read_ADC();
printf("%2u %2u %2u %2u\n\r",val1,val2,val3,i);
st=' ';
}
}
}
}
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In this program, What I want is whenever I click on letter'a', it start loop, when I am not clicking on letter 'a', it will wait for me to click on the letter 'a' again. however, the program works like this way, when power is on, it waiting for me to click on letter 'a', after I click on letter on, the program start for-next loop, and keep loop again without waiting me to click on letter 'a'. please help to find what is the reaseon and how to correct it? |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Wed Oct 13, 2004 2:29 pm |
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The 16F819 does�n have UART.
The reason of the endless loop is
while(getc()=='a') where once keyed "a", the while always is true.
Try this way:
| Code: |
while(1)
{
do
{
char_rcved = getc();
}while(char_rcved !='a');
set_pwm1_duty(0);
delay_ms(100);
for(i=0;i<256;i++)
{
set_pwm1_duty(i);
delay_ms(50);
set_adc_channel( 0 );
delay_us(100);
val1 = Read_ADC();
set_adc_channel( 1 );
delay_us(100);
val2 = Read_ADC();
set_adc_channel( 3 );
delay_us(100);
val3 = Read_ADC();
printf("%2u %2u %2u %2u\n\r",val1,val2,val3,i);
st=' ';
char_rcved = 0; // clear char_rcved to break the TRUE condition
// inside the do while cycle
} // for...
} // while(1)
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best wishes,
Humberto |
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dyeatman
Joined: 06 Sep 2003
Posts: 1934
Location: Norman, OK
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| one idea... |
| Posted: Wed Oct 13, 2004 3:37 pm |
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Do you think an integer only goes from 0 to 255 might have something to do with it?
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Guest
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| Posted: Wed Oct 13, 2004 4:28 pm |
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| I did as you advised, I still get the same result anyway. |
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Guest
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| Posted: Wed Oct 13, 2004 4:33 pm |
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what do you mean by
| Quote: |
Do you think an integer only goes from 0 to 255 might have something to do with it?
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do you thing I should go to a big loop, but I do not a bigger loop anyway? |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Wed Oct 13, 2004 5:19 pm |
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| Quote: | while(getc()=='a') where once keyed "a", the while always is true.
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Wrong. It will wait for another press.
| Quote: | | Do you think an integer only goes from 0 to 255 might have something to do with it? |
What he means is that i<256 will always be true since the next value after 255 is 0 for an 8bit int. Change it to i<255 or make i be a int16. |
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Guest
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| Posted: Wed Oct 13, 2004 6:34 pm |
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| Thank you, Dayman and mark is right |
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