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使用环境:
处理器:S3C2440A IR receiver: HS0038 接收口: GPB9(非中断IO口)
程序设计思路:
因为是普通IO口接收遥控，不能使用中断来检测IR波形。这里使用查询的方式来进行检测。
由于遥控波形的不稳定性，一般认为合理误差在20%或30%以内。
NEC波形的最小水平是560us，所以我们设定一个100us的定时器对IO口做检测。另设置一个计数器对高低电平计数。
注意事项:
定时器输出时钟频率=PCLK/(prescaler+1)/divider
其中prescaler值由TCFG0决定，divider值由TCFG1决定，而prescaler只能取0~255之间的整数，divider只能取2、4、8和16。
如果程序定义多个定时器，要先设定满足多个定时器时钟频率的prescaler,再设定divider.
以下是部分程序：
#define HEAD_LOW_MIN (63) // 9000*0.7/100 = 63
#define HEAD_LOW_MAX (117) //9000*1.3/100 = 117
#define HEAD_HIGH_MIN (31) //4500*0.7/100=31
#define HEAD_HIGH_MAX (59) //4500*1.3/100 = 59
#define CODE_LOW_MIN (4) //560*0.7/100=3.92
#define CODE_LOW_MAX (8) //560*1.3/100 =7.28
#define CODE0_HIGH_MIN CODE_LOW_MIN //
#define CODE0_HIGH_MAX CODE_LOW_MAX
#define CODE1_HIGH_MIN (12) //1690*0.7/100 = 11.83
#define CODE1_HIGH_MAX (22) //1690*1.3/100 = 21.97
#define REP_LOW_MIN HEAD_LOW_MIN
#define REP_LOW_MAX HEAD_LOW_MAX
#define REP_HIGH_MIN (15) //2250*0.7/100 = 15.75
#define REP_HIGH_MAX (30) //2250*1.3/100 = 29.25
#define FLAME_INTERVAL_MIN (864) //108000*0.8/100=864
#define FLAME_INTERVAL_MAX (1296) //108000*1.2/100=1296
#define HIGH_LEVEL (1)
#define LOW_LEVEL (0)
#define IR_IDLE 0
#define IR_HEAD 1
#define IR_CODES 2
#define IR_REPEAT_9 3
#define IR_REPEAT_2_25 4
#define IR_REPEAT_STOP 5
static U8 last_level;
static U8 ir_state;
static U8 bits_received; //count how many bits received.
static U8 code_received; //whether receive a data or not.
static U8 repeat_received; //whether receive a repeat code or not.
static U32 ir_counter; //count how many cycle a level last for.
static U32 ir_data; //record the received IR bits.
static U32 ir_interval_counter; //record the flame interval. normal 108ms.
static U8 customer_data;
static U8 command_data;
int Test_IrDecoder()
{
Uart_Printf("\n==irda decoder=\n");
Uart_Printf("press ESC to exit\n");
rGPBCON&= ~(0x10<<18); //GPB9:IRDA
Ir_DecodeError();
//TIMER3 is used for delay function.
rTCFG0 &= ~(0xff<<8);
rTCFG0 |= 3<<8; //prescaler = 3
rTCFG1 &= ~(0xf<<16);
rTCFG1 |= 3<<16; //mux = 1/16 utput clock freq. = 50*1000000/16/4;
//781250Hz. cycle=1/781250= 1.28us
rTCNTB4 = 78; // 1.28us*75 =100 us.
rTCON &= ~(0x07<<20);
rTCON |= 0x700000;
rTCON &= ~0x200000; //clear manual update bit.
pISR_TIMER4=(U32)IsrTime4; //set timer4 entry point, that is, install timer.
rSRCPND = BIT_TIMER4; //clear the interrupt apply bit.
rINTPND = BIT_TIMER4;
rINTMSK &= ~BIT_TIMER4; //enable timer4
while(1)
{
Delay(10);
....
if ( Uart_GetKey() == ESC_KEY ) break;
}
return(0);
}
//NEC
// 9ms 4.5ms 2.25ms
// __ _____ __ _1.12ms
// | | || |||
// | | || |||
// |________| || |||
// head code 1 0
static void __irq IsrTime4(void)
{
U8 current_level;
U32 m,m_invert;
current_level= HIGH_LEVEL;
rSRCPND |= BIT_TIMER4;
rINTPND |= BIT_TIMER4; //Clear
if ((rGPBDAT&0x200) != 0x200)
{
current_level = LOW_LEVEL;
}
switch (ir_state)
{
case IR_IDLE:
if (LOW_LEVEL == current_level)
{
ir_counter = 1;
ir_state = IR_HEAD;
}
break;
case IR_HEAD: //Ready to receive IR head.
if (LOW_LEVEL == current_level)
{
if (LOW_LEVEL == last_level )
{
ir_counter++;
if (ir_counter > HEAD_LOW_MAX)
{
Ir_DecodeError();
}
}
else if (HIGH_LEVEL == last_level)
{
if (ir_counter >= HEAD_HIGH_MIN)
{
ir_counter = 1;
ir_state = IR_CODES; //Head received, ready to receive IR data.
}
else
{
Ir_DecodeError();
}
}
}
else //current_level = High
{
if (HIGH_LEVEL == last_level)
{
ir_counter++;
if (ir_counter > HEAD_HIGH_MAX)
{
Ir_DecodeError();
}
}
else
{
if (ir_counter >= HEAD_LOW_MIN)
{
ir_counter = 1;
}
else
{
Ir_DecodeError();
}
}
}
break;
case IR_CODES: //Ready to receive 32-bit IR codes.
if (LOW_LEVEL == current_level)
{
if (LOW_LEVEL == last_level )
{
ir_counter++;
if (ir_counter > CODE_LOW_MAX)
{
Ir_DecodeError();
}
}
else if (HIGH_LEVEL == last_level)
{
if ((ir_counter >= CODE0_HIGH_MIN) && (ir_counter <=CODE0_HIGH_MAX))
{
ir_data = (ir_data >>1);
ir_data |= 0x00; // add onr "0" to ir data
ir_counter = 1;
bits_received++;
}
else if ((ir_counter >= CODE1_HIGH_MIN) && (ir_counter <=CODE1_HIGH_MAX))
{
ir_data = (ir_data >>1);
ir_data |= 0x80000000; // add onr "1" to ir data
ir_counter = 1;
bits_received++;
}
else
{
Ir_DecodeError();
}
if ((16 == bits_received)||(32 == bits_received))
{
m = ((ir_data>>16) & 0x000000FF);
m_invert = ((ir_data>>24) &0x000000FF);
if ((m^m_invert)!=0x000000FF)
{
Ir_DecodeError();
}
if (32 == bits_received)
{
code_received = TRUE; //First Key received.
ir_state = IR_REPEAT_9; //Ready to check whether repeat key
ir_counter = 1; //received or not.
}
}
}
}
else //current_level = High
{
if (HIGH_LEVEL == last_level)
{
ir_counter++;
if (ir_counter > CODE1_HIGH_MAX)
{
Ir_DecodeError();
}
}
else
{
if (ir_counter >= CODE_LOW_MIN)
{
ir_counter = 1;
}
else
{
Ir_DecodeError();
}
}
}
break;
case IR_REPEAT_9:
if (ir_interval_counter < FLAME_INTERVAL_MAX)
{
if (LOW_LEVEL == current_level)
{
if (HIGH_LEVEL == last_level)
{
if (ir_interval_counter >= FLAME_INTERVAL_MIN)
{
ir_interval_counter = 0;
ir_counter = 1;
}
else
{
Ir_DecodeError();
}
}
else
{
ir_counter++;
if (ir_counter > REP_LOW_MAX)
{
Ir_DecodeError();
}
}
}
else //current HIGH level
{
if (HIGH_LEVEL == last_level)
{
if (ir_interval_counter == FLAME_INTERVAL_MAX)
{
Ir_DecodeError();
}
}
else
{
if (ir_counter >= HEAD_LOW_MIN)
{
ir_state = IR_REPEAT_2_25;
ir_counter = 1;
}
else
{
Ir_DecodeError();
}
}
}
}
else
{
Ir_DecodeError();
}
break;
case IR_REPEAT_2_25:
if (LOW_LEVEL == current_level)
{
if (ir_counter >= REP_HIGH_MIN)
{
ir_counter = 1;
ir_state = IR_REPEAT_STOP;
}
else
{
Ir_DecodeError();
}
}
else //current HIGH level
{
ir_counter++;
if (ir_counter >= REP_HIGH_MAX)
{
Ir_DecodeError();
}
}
break;
case IR_REPEAT_STOP:
if (LOW_LEVEL == current_level)
{
ir_counter++;
if (ir_counter > CODE_LOW_MAX)
{
Ir_DecodeError();
}
}
else //current HIGH level
{
ir_counter++;
if (ir_counter >= REP_HIGH_MAX)
{
Ir_DecodeError();
}
}
break;
}
if (ir_state != IR_IDLE)
{
last_level = current_level;
ir_interval_counter++;
if (ir_interval_counter > FLAME_INTERVAL_MAX)
{
Ir_DecodeError();
}
}
}
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发表于 2011-01-06 17:32