Sophi
Joined: 14 Jun 2005
Posts: 64
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| Problem with ltc1298 and comparator interupt |
 Posted: Tue Mar 21, 2006 8:09 pm |
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Hi- I started with the following code- it is a comparator interrupt on PortA . Pins A0, A1 wired together to a pushbutton switch. It works reliably.
| Code: | #include <16F877A.H>
#fuses HS,NOWDT,NOPROTECT, PUT, BROWNOUT, NOLVP // HS for 20 mHz, fuses specific to chip
#use delay(clock=20000000) // adjust for resonator frequency
#use i2c(Master, SDA=PIN_C4, SCL=PIN_C3) // set up options
#include <LCD_16f877A.c>
#include <ltc1298_sk.c>
#include <24128.c> // try removing
#use fast_io(c)
#use fast_io(a)
#use fast_io(b)
#include <stdlib.h>
#byte PORTB=6
//this is the one that works
#INT_COMP
comp_isr() {
delay_ms(25); //debounce
printf(lcd_putc,"\fInterrupt loop ");
delay_ms(500);
}
void main() {
init:
set_tris_a(0b00000011); // sets PORTA
set_tris_b(0x00);
set_tris_c(0b00110111); // set all PORTC, pin_C1 in for marry
lcd_init();
lcd_putc("\nLucky13");
delay_ms(1000);
setup_comparator(A0_VR_A1_VR); // Mode 2 -A0, A1 inputs to
// 2 comparators, compare with Vref
setup_vref(VREF_HIGH|2); // (mode|value) 5*value/32+1.25=vref
// value = 2, vref = 1.56V
enable_interrupts(INT_COMP);
enable_interrupts(GLOBAL);
delay_ms(2000);
adc_init();
delay_us(10);
while(1)
{
lcd_putc("\fMain loop");
delay_ms(500);
}
} |
Then using the CCS driver for the ADLTC1298, I changed the pinouts to | Code: | #define ADC_CS PIN_A3
#define ADC_CLK PIN_E0 // output from MP
#define ADC_DIN PIN_E2 // output from MP
#define ADC_DOUT PIN_E1 // input to MP |
and the delays in the driver to "delay_cycles(1);"
I think my wiring is OK.
I added (tested and working) code to the one above:
| Code: | #include <16F877A.H>
#fuses HS,NOWDT,NOPROTECT, PUT, BROWNOUT, NOLVP // changed to HS for 20 mHz
#use delay(clock=20000000) // adjust for resonator frequency
#use i2c(Master, SDA=PIN_C4, SCL=PIN_C3) // set up options
#include <LCD_16f877A.c>
#include <ltc1298_sk.c>
#use fast_io(a)
#use fast_io(b)
#use fast_io(c)
#use fast_io(e)
#include <stdlib.h>
#byte PORTB=6
//*****************************************************************
//function to use variable 16 bit delay...are you reading this PCM? I owe you bigtime for this function!!
void long_delay_us (long int count)
{
char i;
i = (char)(count >> 8); // typecast count >>8 (right shift count) as char
while(i >= 1) // loop while i >= 1
{
i--;
delay_us(248); // delay 253 us, adjustable
restart_wdt(); // restart watchdog timer
}
delay_us((char)count); // use built-in function delay_us to typecast count
}
#INT_COMP
comp_isr(){
delay_ms(25); //debounce
printf(lcd_putc,"\fInterrupt loop ");
delay_ms(500);
}
void main()
{
int i = 0; // loop count
float ad12, ad12temp; // digital output of a/d channel 0 (light)
// digital output of a/d channel 1 (temp sensor)
long int count;
set_tris_a(0b11110011); // sets port a direction 0=out 1=in
set_tris_b(0x00);
set_tris_c(0b00110011); // set all PORTC, pin_C1 in for marry
set_tris_e(0b11111100); // set all PORTE, pin_C1 in for marry
init:
lcd_init();
lcd_putc("\fFab 15 "); // welcome
delay_ms(1000);
setup_comparator(A0_VR_A1_VR); // Mode 2 -A0, A1 inputs to
// 2 comparators, compare with Vref
setup_vref(VREF_HIGH|2); // (mode|value) 5*value/32+1.25=vref
// value = 2, vref = 1.56V
enable_interrupts(INT_COMP);
enable_interrupts(GLOBAL);
adc_init();
do{
ad12 = read_analog(0) >> 4; // get a/d value (channel 0) and shift
ad12temp = read_analog(1) >> 4; // get a/d value (channel 1) and shift
lcd_gotoxy(1,1); // start at 1st line
printf(lcd_putc,"AD = %5.0f", ad12); // print to LCD
delay_us(1500);
for (i=1; i<=100; i++) // start of light sensor action
{
count = ((0.244*ad12)+1000); // y=mx+b-function to relate ad12 and servo 1000us - 2000us
// b = 1000, m = .244, for light sensor
output_high (PIN_C2); // servo out high
long_delay_us (count); // function call allow 16 bit us
output_low (PIN_C2); // servo out (off)
long_delay_us (22000-count);
}//end of for
lcd_gotoxy(2,2); // start at 2nd line
printf(lcd_putc,"\nTemp = %5.0f", ad12temp);// print temperature sensor reading to LCD
delay_us(750);
}while(1); // while true
}
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On startup, the code goes straight to the interrupt loop. When I reset, the software runs in the main loop and interrupts when I push the button. But then it hangs in the interrupt...forever....until I push the button again and it goes back to main. I can push the button over and over and flip back between threads.
I have no experience with interrupts and am at a total loss for what is wrong.
Another wierd thing is that the A/D works great but there is no signal on the clock pin (7 on A/D, 8 on MP). Unless I have a bad probe...
Thanks muchly for any help-
SophE |
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