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feederic
Joined: 08 Apr 2008
Posts: 7
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| Problems with Button Delay on 16f887 |
 Posted: Tue Apr 08, 2008 8:42 pm |
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I'm new to the PIC programming scene and have been teaching myself while programming a school project.
I've been having problems getting a button to react instantly in my code while using the A2D and case statements.
Namely, I've got a A2D converter controlling the speed of 4 scrolling LEDs. I have 4 buttons, one assigned to each LED, and I want the button to pause its corresponding LED if and only the LED is on.
My problem is I need to hold the button down for a half second (sometimes longer) to get it to react. Sometimes it will react 2 seconds later.
| Code: |
#include <16F887.h> // header file for the PIC16F887
// includes built-in functions and constants
// for arguments/returns.
#use delay (clock = 4MHZ)
#use fast_io(A) // all other ports default to 'standard_io'
#use fast_io(B) // fast_io means the tris bits only change
#use fast_io(C)
#use fast_io(D)
#FUSES INTRC,NOWDT,NOPUT,NOMCLR,NOPROTECT,NOCPD,NOBROWNOUT,NOIESO,NOFCMEN,NOLVP
long int state_delay = 0;
int state_delay_temp = 0;
int mult = 20;
unsigned char state_led = 0;
struct adc_result
{
int8 value;
int1 new_flag;
} adc_conversion;
void init_io()
{
SET_TRIS_A(0x0F); // bit 0 = output, 1 = input
SET_TRIS_B(0x3F); // bit 0 = output, 1 = input
SET_TRIS_D(0xF0);
SET_TRIS_C(0x00);
OUTPUT_E(0x00);
}
void init_adc()
{
// Set up RA0 as the only analog input, using VDD and VSS
// as the references
SETUP_ADC_PORTS(sAN0 | VSS_VDD);
// Turn on ADC and use Fosc/8 as the conversion clock
// (Fosc = 4MHz)
SETUP_ADC(ADC_CLOCK_DIV_8);
// Set channel for conversion to AN0 (on RA0)
SET_ADC_CHANNEL(0);
// start the first conversion
READ_ADC(ADC_START_ONLY);
}
#INT_RTCC // This function will be called on a Timer0 interrupt
void timer0_interrupt_service()
{
// channel is always set to AN0. Otherwise we might change
// it here
// Get last conversion result.
adc_conversion.value = READ_ADC(ADC_READ_ONLY);
adc_conversion.new_flag = 1; // new value
delay_ms(state_delay);
state_led++;
// start next conversion
READ_ADC(ADC_START_ONLY);
}
void main()
{
int switch_count = 0;
int temp1 = 0;
int led_display = 0;
adc_conversion.value = 0;
adc_conversion.new_flag = 0;
init_io();
init_adc();
SETUP_TIMER_0(RTCC_INTERNAL | RTCC_DIV_256);
ENABLE_INTERRUPTS(GLOBAL);
ENABLE_INTERRUPTS(INT_RTCC);
while(1)
{
// look for a new conversion result
if (adc_conversion.new_flag == 1)
{
state_delay_temp = adc_conversion.value;
state_delay = _mul(state_delay_temp, mult);
adc_conversion.new_flag = 0;
led_display = 0;
}
if (INPUT_STATE(PIN_B0) == 0 && state_led == 0)
{
if (switch_count < 4)
{
switch_count ++;
if (switch_count == 4)
{
output_d(1);
}
}
}
else
{
switch_count = 0;
}
if (INPUT_STATE(PIN_B1) == 0 && state_led == 1)
{
if (switch_count < 4)
{
switch_count ++;
if (switch_count == 4)
{
output_d(2);
}
}
}
else
{
switch_count = 0;
}
if (INPUT_STATE(PIN_B2) == 0 && state_led == 2)
{
if (switch_count < 4)
{
switch_count ++;
if (switch_count == 4)
{
output_d(4);
}
}
}
else
{
switch_count = 0;
}
if (INPUT_STATE(PIN_B3) == 0 && state_led == 3)
{
if (switch_count < 4)
{
switch_count ++;
if (switch_count == 4)
{
output_d(8);
}
}
}
else
{
switch_count = 0;
}
switch (state_led)
{
case 0:
led_display = 1;
if(INPUT_STATE(PIN_D7) == 1)
{
state_led =1;
break;
}
OUTPUT_D(1);
break;
case 1:
led_display = 2;
if(INPUT_STATE(PIN_D6) == 1)
{
state_led = 2;
break;
}
OUTPUT_D(2);
break;
case 2:
led_display = 4;
if(INPUT_STATE(PIN_D5) == 1)
{
state_led = 3;
break;
}
OUTPUT_D(4);
break;
case 3:
led_display = 8;
if(INPUT_STATE(PIN_D4) == 1)
{
state_led = 4;
break;
}
OUTPUT_D(8);
break;
case 4:
state_led = 0;
break;
case 5:
OUTPUT_D(led_display);
state_led = 5;
break;
}
}
}
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I have a variable state_led that is being incremented in the Timer0 ISR, this increment will cause the next led to light in the case statements.
I would greatly appreciate any help. |
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Matro
Guest
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| Posted: Wed Apr 09, 2008 1:36 am |
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I would have coded that differently.
Do a read_adc() only once per loop (endless loop of the main()).
Use interrupt-on-change feature of the port B to handle button pushes.
Here in your timer interrupt, the read_adc() will slow down the code and the delay_ms() too.
When this interrupt is triggered, main() execution is stopped so if this interrupt continuously "breaks" the main() the reaction delay will be very long.
I think you don't need to acquire very often the new adc_value (once per loop should be sufficient) so place the read in the main() loop.
And (if your buttons are connected to port B) use the interrupt-on-change of this port to handle button changes.
Matro. |
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Guest
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| Posted: Wed Apr 09, 2008 12:26 pm |
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Thank you Matro, I knew the problem was around the a2d conversion but didn't know how to remedy it.
I will try out all of your suggestions immediately! |
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Guest
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| Posted: Thu Apr 10, 2008 4:53 pm |
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I tried the suggested fixes, and have had some success.
The button delays are gone, and the a2d has smoothed out when turning the pot.
The only issue I have right now is being able to generate a interrupt the whole time an LED is lit.
For clarity, I have RB1-4 assigned to LEDs 1-4 (on PortD)
When LED 1 is on and button RB1 is pushed I want to generate the inerrupt.
When LED 2 is on and button RB2 is pushed I want ""
...and so on.
I'm pretty much using this code in the RB interrupt code.
| Code: | if (INPUT_STATE(PIN_B2) == 0 && state_led == 2)
{
if (switch_count < 4)
{
switch_count ++;
if (switch_count == 4)
{
output_d(4);
}
}
}
else
{
switch_count = 0;
}
|
anyone have any suggestions?? |
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feederic
Joined: 08 Apr 2008
Posts: 7
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| Posted: Thu Apr 10, 2008 4:59 pm |
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That was my post above.
I also did change the button polling for portB to interrupt on change. |
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feederic
Joined: 08 Apr 2008
Posts: 7
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| Posted: Wed Apr 16, 2008 8:42 pm |
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Hi everyone, I'm still having a few problems I can't work out.
The buttons work fine except when the LED speed is slow. When the delay coming from the A2D produces a large value, the portB interrupts work unless we hold the button down for about a second.
My code thus far:
| Code: | #include <16F887.h> // header file for the PIC16F887
// includes built-in functions and constants
// for arguments/returns.
#use delay (clock = 4MHZ)
#use fast_io(A) // all other ports default to 'standard_io'
#use fast_io(B) // fast_io means the tris bits only change
#use fast_io(C)
#use fast_io(D)
// when we explicitly set them.
// FUSES sets the PIC16F887 Configuration Words. See top of the header file
// 16F887.h for fuse option constants.
#FUSES INTRC,NOWDT,NOPUT,NOMCLR,NOPROTECT,NOCPD,NOBROWNOUT,NOIESO,NOFCMEN,NOLVP
long int state_delay = 0;
int state_delay_temp = 0;
int mult = 20;
unsigned char state_led = 0;
int led_display = 0;
int switch_count1 = 0;
int temp = 0;
struct adc_result
{
int8 value; // ADC built-in functions default to 8 bit result.
int1 new_flag; // 1-bit falg to indicate a new (fresh) value
} adc_conversion;
void init_io()
{
// set up PORTA so RA0 is an input for the ADC, RA1-RA7 are outputs
SET_TRIS_A(0x0F); // bit 0 = output, 1 = input
// set up PORTB so RB0 is an input for the switch SW1, RB1-RB7 are outputs
SET_TRIS_B(0x3F); // bit 0 = output, 1 = input
SET_TRIS_D(0xF0);
// set up remaining ports to be all outputs
SET_TRIS_C(0x00);
PORT_B_PULLUPS(0x3f);
OUTPUT_E(0x00);
}
void init_adc()
{
// Set up RA0 as the only analog input, using VDD and VSS
// as the references
SETUP_ADC_PORTS(sAN0 | VSS_VDD);
// Turn on ADC and use Fosc/8 as the conversion clock
// (Fosc = 4MHz)
SETUP_ADC(ADC_CLOCK_DIV_8);
// Set channel for conversion to AN0 (on RA0)
SET_ADC_CHANNEL(0);
// start the first conversion
}
#INT_RTCC // This function will be called on a Timer0 interrupt
void timer0_interrupt_service()
{
// channel is always set to AN0. Otherwise we might change
// it here
// Get last conversion result.
adc_conversion.value = READ_ADC(ADC_READ_ONLY);
adc_conversion.new_flag = 1; // new value
delay_ms(state_delay);
state_led++;
}
#INT_RB
void button_interrupt_service()
{
if (INPUT_STATE(PIN_B1) != 1 )
{
while(1)
{
output_d(1);
if(input_state(pin_b5) == 0)
{
break;
}
}
}
else
{
break;
}
if (INPUT_STATE(PIN_B2) != 1 )
{
while(1)
{
output_d(2);
if(input_state(pin_b5) == 0)
{
break;
}
}
}
else
{
break;
}
if (INPUT_STATE(PIN_B3) != 1 )
{
while(1)
{
output_d(4);
if(input_state(pin_b5) == 0)
{
break;
}
}
}
else
{
break;
}
if (INPUT_STATE(PIN_B4) != 1 )
{
while(1)
{
output_d(8);
if(input_state(pin_b5) == 0)
{
break;
}
}
}
else
{
break;
}
}
void main()
{
// int1 led_bar_right = 0; // default is led bar graph starting on the left (DS0)
int switch_count = 0; // used for debouncing the switch
int switch_count1 = 0; // used to compute the number of LED "bars" to display
// int temp1 = 0; temporary working variable
// int led_display = 0; // led display value
int sound = 0;
int start =1;
int temp = 0;
// initialize global variables
adc_conversion.value = 0;
adc_conversion.new_flag = 0;
// Set up MCU
init_io();
init_adc();
// Timer 0 runs off internal clock with 1:256 prescaler
// This means it should run over every ((256*256)/(4MHz/4)) = 65.5ms
// It will be used to start an ADC conversion.
SETUP_TIMER_0(RTCC_INTERNAL | RTCC_DIV_256);
ENABLE_INTERRUPTS(GLOBAL); // enable interrupts in general to be active
ENABLE_INTERRUPTS(INT_RTCC); // enable the interrupt for Timer 0
ENABLE_INTERRUPTS(INT_RB);
while(1)
{
READ_ADC(ADC_START_ONLY);
if( start ==1)
{
// look for a new conversion result
if (adc_conversion.new_flag == 1)
{
state_delay_temp = adc_conversion.value;
state_delay = _mul(state_delay_temp, mult);
adc_conversion.new_flag = 0; // reset flag
led_display = 0; // clear display variable
}
if (INPUT_STATE(PIN_D7) == 1 && INPUT_STATE(PIN_D6) == 1 && INPUT_STATE(PIN_D5) == 1 && INPUT_STATE(PIN_D5) == 1)
{ // switch is low when pressed
if (switch_count < 4)
{ // increment the count on all consecutive checks where switch is pressed
// to a max of 3
switch_count ++;
// if we've seen 3 consecutive checks where the switch is pressed
// it's considered a valid switch press. Reverse the bar graph
if (switch_count == 4)
{
state_led = 6;
}
}
}
else
{ // anytime switch is detected as not pressed, reset the count
switch_count = 0;
}
if(INPUT_STATE(PIN_A2) == 1)
{
while(led_display ==1)
{
output_high(PIN_c6);
delay_us(500);
output_low(PIN_c6);
delay_us(500);
break;
}
while(led_display ==2)
{
output_high(PIN_c6);
delay_us(600);
output_low(PIN_c6);
delay_us(600);
break;
}
while(led_display==4)
{
output_high(PIN_c6);
delay_us(700);
output_low(PIN_c6);
delay_us(700);
break;
}
while(led_display ==8)
{
output_high(PIN_c6);
delay_us(800);
output_low(PIN_c6);
delay_us(800);
break;
}
}
switch (state_led)
{
case 0:
led_display = 1;
if(INPUT_STATE(PIN_D7) == 1)
{
state_led =1;
break;
}
OUTPUT_D(1);
break;
case 1:
led_display = 2;
if(INPUT_STATE(PIN_D6) == 1)
{
state_led = 2;
break;
}
OUTPUT_D(2);
break;
case 2:
led_display = 4;
if(INPUT_STATE(PIN_D5) == 1)
{
state_led = 3;
break;
}
OUTPUT_D(4);
break;
case 3:
led_display = 8;
if(INPUT_STATE(PIN_D4) == 1)
{
state_led = 4;
break;
}
OUTPUT_D(8);
break;
case 4:
state_led = 0;
break;
case 5:
OUTPUT_D(led_display);
state_led = 5;
break;
case 6:
OUTPUT_D(0x0f);
state_led=4;
}
}
}
} |
I'm pretty sure my problem lies here:
| Code: | #INT_RTCC // This function will be called on a Timer0 interrupt
void timer0_interrupt_service()
{
// channel is always set to AN0. Otherwise we might change
// it here
// Get last conversion result.
adc_conversion.value = READ_ADC(ADC_READ_ONLY);
adc_conversion.new_flag = 1; // new value
[b]delay_ms(state_delay);[/b]
state_led++;
} |
When the delay is large I can't generate an interrupt immediately. Is there any way I can keep this delay going while being able to generate an interrupt on portB?
I'm fresh out of ideas right now. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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feederic
Joined: 08 Apr 2008
Posts: 7
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| Posted: Wed Apr 16, 2008 9:22 pm |
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That is an excellent link!
I'll post up progress hopefully by monday. |
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feederic
Joined: 08 Apr 2008
Posts: 7
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| Posted: Mon Apr 21, 2008 12:58 am |
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Thanks PCM PROGRAMMER and MATRO!
Everything is working as desired!  |
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