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jaethelegend
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| simple arithmatic BCD_RTN |
 Posted: Sun Jun 07, 2009 9:55 pm |
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Hi, I am using CCP1 port to measure the length of pulses.
I have couple of problems
1), I am using BCD_ routine which separates the 4 digits for displaying onto the LCD which is
| Code: |
void BCD_RTN(buffer){
thou_digit = buffer/1000;
buffer-= thou_digit*1000;
hund_digit = buffer/100;
buffer -= hund_digit*100;
ten_digit = buffer/10;
one_digit = buffer-ten_digit*10;
} |
However, the algorithm doesn't seem to separate correct digits.
For example, if a variable passed on to the function had the value of
1243, or 0x04DB, it yields, thou_digit = 0, hund_digit = 2, ten_digit = 2, one_digit = 0, which is very off.
Is it because I am using unsigned int16 variable? Is there anything I should keep in mind when computing with those type of variable??
Below is my complete coding.
Thanks in advance
| Code: |
#include<C:\Documents and Settings\Microsoft\My Documents\PIC\Header\16f886.h>
#include<C:\Documents and Settings\Microsoft\My Documents\PIC\Header\def_16f886.h>
#fuses INTRC_IO,DEBUG
#use delay(clock = 1000000)
#define LCD_PORT PORTA
#define LCD_TRIS TRISA
#include<C:\Documents and Settings\Microsoft\My Documents\PIC\Header\LCD4bit.h>
unsigned int16 this_time = 0; //stores the time that was just captured
unsigned int16 last_time = 0; //stores the time that was captured last.
unsigned int16 diff = 0;
//unsigned int16 frequency_in_KHz = 0;
unsigned int16 thou_digit = 0;
unsigned int16 hund_digit = 0;
unsigned int16 ten_digit = 0;
unsigned int16 one_digit = 0;
void Init_rtn(){
LCD_INIT(0x28);
osccon = 0x45;
TRISC2 = 1; //CCP1 input
PORTC2 = 0;
GIE = 1;
PEIE = 1;
CCP1IE = 1;
PIR1 = 0x00;
CCP1CON = 0x05;// Capture mode, every rising edge
T1CON = 0x01;
TMR1L = 0x00;
TMR1H = 0x00;
goto_xy(0,0);
send_char("Difference");
send_cmd(CURSOR_OFF_BLINK_OFF);
}
#int_ccp1
void ccp1_isr(){
last_time = this_time;//Last "this_time" becomes "last_time"
this_time = CCPR1H<<8;
this_time = this_time|CCPR1L;
//Wrap around has not occured.
if(this_time>last_time) diff = this_time-last_time;
//wrap around has occured.
else diff = (2^16) -1 - last_time + this_time;
delay_us(10);
//frequency_in_KHz = 4*(10^3)/diff;
}
void BCD_RTN(buffer){
thou_digit = buffer/1000;
buffer-= thou_digit*1000;
hund_digit = buffer/100;
buffer -= hund_digit*100;
ten_digit = buffer/10;
one_digit = buffer-ten_digit*10;
}
void disp_rtn(void){
BCD_rtn(diff);
goto_xy(5,1);
send_char(ascii_num_table[thou_digit]);
send_char(ascii_num_table[hund_digit]);
send_char(ascii_num_table[ten_digit]);
send_char(ascii_num_table[one_digit]);
}
void main(void){
Init_rtn();
while(1){
disp_rtn();
}
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Jun 07, 2009 10:30 pm |
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Do you want to display a number on a normal 2x16 LCD ?
Use printf to convert the number to ASCII. It's much easier.
Also use the re-direction feature of printf, to send the output
to the lcd_putc() routine, so it will be displayed on the LCD.
http://www.ccsinfo.com/forum/viewtopic.php?t=33390 |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Sun Jun 07, 2009 11:26 pm |
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I agree, that the code is a kind of reinventing the square wheel.
Regarding it's failure, you may want to correct it to
| Code: | | void BCD_RTN(int16 buffer); |
CCS has a default integer data type, it's int8. |
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