/ *
* IR reception
* 05/Sep/1999 JLS & CAE
* jls at certi.ufsc.br
* cae at certi.ufsc.br
* CC5xFree v3.0E (http://www.bknd.com)
* use CC1B for SX
*/
/*
Sony Data format: 12 bits
Bit zero:
400
+--+ +...
| | |
+ +---+
800
Bit one:
400
+--+ +...
| | |
+ +------+
1400
Frame:
400 400
--+ +--+ +--+ +--+
| | | | | | |
+---2600---+ +---+ +------+ +...
800 1400
Decoding algorithm:
- Detect 2600us pulse,
- measure next high pulse as P1 (400us)
- measure next low pulse as P2 (800/1400us)
- store min(P1)
- store max(P2)
After all measurements:
- calculate mean = (max-min)/2 + min
- For all (P1,P2) measured:
. Add P1+P2=P3
. If P3< mean => bit is zero
. If P3>=mean => bit is one
Measures with Timer0 & Prescaler:16
2600us = 162
1400us = 87
800us = 50
400us = 25
400+800 = 25+50 = 75
400+1400 = 25+87 = 112
mean ~= (112-75)/2+75 = 18+75 = 93
*/
#define _sx28_
#include <sx28.h>
#ifdef _12C508_
bit _TxOUT @ GP0;
bit RxD_pin @ GP1;
bit IR_input @ GP2;
#else
#define RP0 STATUS.5
#pragma update_RP 0 /* OFF */
#define DEF_TRISA 0
#define DEF_TRISB 6
bit Rele @ PORTA.1;
bit IR_input @ PORTB.1;
bit RxD_pin @ PORTB.2;
bit _TxOUT @ PORTB.3;
bit LED @ PORTB.4;
#endif
#ifdef _sx28_
unsigned char x,y;
bank0 unsigned char r[4];
bank0 unsigned char med,min,max,rxBuf;
bank1 unsigned char buff[16];
bank2 unsigned char buff2[16];
#else
unsigned char x,y,med,min,max,rxBuf;
unsigned char r[4];
unsigned char buff[16];
unsigned char buff2[16];
#endif
void TxSerial (unsigned char txBuf);
/*--------------------------------------------------------------------------*/
void TxEnter (void) {
/*--------------------------------------------------------------------------*/
TxSerial(0xD);
TxSerial(0xA);
}
/*--------------------------------------------------------------------------*/
void TxHexAscii (unsigned char in) {
/*--------------------------------------------------------------------------*/
unsigned char Hex;
Hex = swap(in); // upper nibble
Hex &= 0x0F;
if (Hex<10) Hex += 0x30;
else Hex += 0x37;
TxSerial(Hex);
Hex = in & 0x0F;
if (Hex<0x0A) Hex += 0x30;
else Hex += 0x37;
TxSerial(Hex);
}
/*--------------------------------------------------------------------------*/
void Delay_uSeg (unsigned char timeout) {
/*--------------------------------------------------------------------------*/
// delay = 3*timeout + 7uS (including call and return)
while (1) {
timeout--;
if (timeout==0) {
nop();
nop();
return;
}
}
}
/*--------------------------------------------------------------------------*/
void TxSerial (unsigned char txBuf) {
/*--------------------------------------------------------------------------*/
/*
;---------------------------------------------------------------------------*
; Transmit 1 start bit Lo, 8 data bits and 1 stop bit Hi at 9600 bps
; No Parity
; Byte time = 1.040 mS
; Bit time = 104 uS (0.16% erro w/4.00 Mhz Internal RC)
; Input : W = byte to be transmitted
; Output: byte transmitted by serial pin
;---------------------------------------------------------------------------*
*/
char idx;
while (1)
{
Carry = 0; // start bit
for (idx=10; idx; idx--) // 3us
{
_TxOUT = Carry; // 4us
Delay_uSeg(28); // 91us (28*3+7)
Carry = 1; // 1us
txBuf = rr(txBuf); // 1us
nop(); // 1us
} // 3us
return;
}
}
/*--------------------------------------------------------------------------*/
void RxSerial (void) {
/*--------------------------------------------------------------------------*/
/*
;---------------------------------------------------------------------------*
; Receives 1 start bit Lo, 8 data bits and 1 stop bit Hi at 9600 bps
; No Parity
; Byte time = 1.040 mS
; Bit time = 104 uS (0.16% erro w/4.00 Mhz Internal RC)
;
; False start bit check
;
; Start bit hunting timeout = 4*1.283ms
;
; Input : none
; Output : Carry = 1 => success
; rxBuf = input byte
; Carry = 0 => error (timeout or stop bit=0)
;---------------------------------------------------------------------------*
*/
char idx;
rxBuf = 4; // 5.135 ms timeout
idx = 0;
while (1)
{
while (RxD_pin) // input "high"
{
if ((-- idx)==0)
{
if ((-- rxBuf)==0)
{
Carry = 0;
return;
}
}
}
Delay_uSeg(14); // 1/2 bit delay (14*3+7)
if (RxD_pin)
continue; // false start bit detection
rxBuf = 0x80; // 8 bits counter and reception buffer
nop();
nop(); // timming adjustment
do
{
Delay_uSeg(30); // (30*3+7)us
Carry = RxD_pin; // bit read
rxBuf = rr(rxBuf); // store and count
}
while (Carry==0);
Delay_uSeg(30); // 1 bit delay
nop(); // timming adjustment
Carry = RxD_pin; // stop bit read
return; // 100 us availiable
}
}
/*--------------------------------------------------------------------------*/
void main (void) {
/*--------------------------------------------------------------------------*/
#ifdef _12C508_
// OSCCAL = W; // OscCal Value - OTP part
OSCCAL = 0xB0; // OscCal Value - Windowed part
GPIO = 0x00;
TRIS = 0x08; // GP3 input
#endif
#ifdef _sx28_
#pragma config &= 0b11010011 // reg 1 = RTCC, no int on RTCC, RTCC internal, prescale, 1:16
PORTA = 0;
PORTB = 0;
DDRA = DEF_TRISA;
DDRA = DEF_TRISB;
PA0 = 0;
PA1 = 0;
PA2 = 0;
#endif
#ifdef _16f84_
INTCON = 0; // no interrupts
PCLATH = 0; // bank 0
PORTA = 0;
PORTB = 0;
TRISA = DEF_TRISA;
TRISB = DEF_TRISB;
RP0 = 1; // RAM bank 1
RP0 = 0; // RAM bank 0
#endif
while (1)
{
/* set vars to start */
min = 255; // min period
max = 0; // max period
y = 0; // pointer to buffer
x = 12; // only 12 bits
/* start bit management */
while (IR_input==1); // wait for 0
/* 2600us start bit */
while (IR_input==0); // wait for 1
TMR0 = 0; // start counter
do
{
// buff[y] = 0;
// buff2[y] = 0;
/* measure high pulse */
while (TMR0==0); // wait TMR0 advance
while (IR_input==1) // wait for 0
{
if (TMR0==0) // timer overflow (4096us) ?
goto frame_end ; // yes, exit
}
buff[y] = TMR0; // store period
med = TMR0; // save high period
TMR0 = 0; // start counter
/* measure low pulse */
while (TMR0==0); // wait TMR0 advance
while (IR_input==0); // wait for 1
buff2[y] = TMR0; // store period
med += TMR0; // total period
TMR0 = 0; // start counter
if (med>=max) max = med; // find max
if (med<min) min = med; // find min
y++; // bump pointer
x--; // dec max bits
}
while (x);
frame_end:
LED = 1;
med = max - min;
med /= 2;
med += min;
r[0] = 0;
r[1] = 0;
r[2] = 0;
r[3] = 0;
x = y; //save the size
do
{
Carry = 0;
r[3] = rl(r[3]);
r[2] = rl(r[2]);
r[1] = rl(r[1]);
r[0] = rl(r[0]);
y--;
max = buff[y];
max += buff2[y];
if (max>=med) r[3]++;
} while (y);
/* now r[0],r[1],r[2], r[3] has the frame */
/* Tx the periods and the encoded word */
TxHexAscii(x*2); //size
TxSerial(0x20);
TxHexAscii(med);
TxEnter();
for(y=0;y<x; y++) {
TxHexAscii(buff[y]);
TxHexAscii(buff2[y]);
TxSerial(0x20);
}
TxEnter();
TxHexAscii(r[0]);
TxHexAscii(r[1]);
TxHexAscii(r[2]);
TxHexAscii(r[3]);
TxEnter();
LED = 0;
}
}
| file: /Techref/scenix/lib/io/osi2/ir/ir2ser.c, 11KB, , updated: 2002/10/25 18:33, local time: 2024/5/11 11:23,
13.59.100.205:LOG IN
|
| ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? <A HREF="http://www.piclist.com/techref/scenix/lib/io/osi2/ir/ir2ser.c"> scenix lib io osi2 ir ir2ser</A> |
| Did you find what you needed? |
|
PICList 2024 contributors:
o List host: MIT, Site host massmind.org, Top posters @none found - Page Editors: James Newton, David Cary, and YOU! * Roman Black of Black Robotics donates from sales of Linistep stepper controller kits. * Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters. * Monthly Subscribers: Gregg Rew. on-going support is MOST appreciated! * Contributors: Richard Seriani, Sr. |
Welcome to www.piclist.com! |
.