demo_14_1.i

AVR原理与应用例程

/*****************************************************
File name           : demo_14_1.c
Chip type           : ATmega16L
Program type        : Application
Clock frequency     : 4.000000 MHz
Memory model        : Small
External SRAM size  : 0
Data Stack size     : 256
*****************************************************/
// CodeVisionAVR C Compiler
// (C) 1998-2001 Pavel Haiduc, HP InfoTech S.R.L.

// I/O registers definitions for the ATmega16


#pragma used+
sfrb TWBR=0;
sfrb TWSR=1;
sfrb TWAR=2;
sfrb TWDR=3;
sfrb ADCL=4;
sfrb ADCH=5;
sfrw ADCW=4;      // 16 bit access
sfrb ADCSRA=6;
sfrb ADMUX=7;
sfrb ACSR=8;
sfrb UBRRL=9;
sfrb UCSRB=0xa;
sfrb UCSRA=0xb;
sfrb UDR=0xc;
sfrb SPCR=0xd;
sfrb SPSR=0xe;
sfrb SPDR=0xf;
sfrb PIND=0x10;
sfrb DDRD=0x11;
sfrb PORTD=0x12;
sfrb PINC=0x13;
sfrb DDRC=0x14;
sfrb PORTC=0x15;
sfrb PINB=0x16;
sfrb DDRB=0x17;
sfrb PORTB=0x18;
sfrb PINA=0x19;
sfrb DDRA=0x1a;
sfrb PORTA=0x1b;
sfrb EECR=0x1c;
sfrb EEDR=0x1d;
sfrb EEARL=0x1e;
sfrb EEARH=0x1f;
sfrw EEAR=0x1e;   // 16 bit access
sfrb UBRRH=0x20;
sfrb UCSRC=0X20;
sfrb WDTCR=0x21;
sfrb ASSR=0x22;
sfrb OCR2=0x23;
sfrb TCNT2=0x24;
sfrb TCCR2=0x25;
sfrb ICR1L=0x26;
sfrb ICR1H=0x27;
sfrb OCR1BL=0x28;
sfrb OCR1BH=0x29;
sfrw OCR1B=0x28;  // 16 bit access
sfrb OCR1AL=0x2a;
sfrb OCR1AH=0x2b;
sfrw OCR1A=0x2a;  // 16 bit access
sfrb TCNT1L=0x2c;
sfrb TCNT1H=0x2d;
sfrw TCNT1=0x2c;  // 16 bit access
sfrb TCCR1B=0x2e;
sfrb TCCR1A=0x2f;
sfrb SFIOR=0x30;
sfrb OSCCAL=0x31;
sfrb OCDR=0x31;
sfrb TCNT0=0x32;
sfrb TCCR0=0x33;
sfrb MCUCSR=0x34;
sfrb MCUCR=0x35;
sfrb TWCR=0x36;
sfrb SPMCR=0x37;
sfrb TIFR=0x38;
sfrb TIMSK=0x39;
sfrb GIFR=0x3a;
sfrb GICR=0x3b;
sfrb OCR0=0X3c;
sfrb SPL=0x3d;
sfrb SPH=0x3e;
sfrb SREG=0x3f;
#pragma used-

// Interrupt vectors definitions


// Needed by the power management functions (sleep.h)
#asm
	#ifndef __SLEEP_DEFINED__
	#define __SLEEP_DEFINED__
	.EQU __se_bit=0x40
	.EQU __sm_mask=0xB0
	.EQU __sm_powerdown=0x20
	.EQU __sm_powersave=0x30
	.EQU __sm_standby=0xA0
	.EQU __sm_ext_standby=0xB0
	.EQU __sm_adc_noise_red=0x10
	.SET power_ctrl_reg=mcucr
	#endif
#endasm






unsigned char tx_buffer[5];         // USART Transmitter buffer
unsigned char tx_wr_index,tx_rd_index,tx_counter;

// USART Transmitter interrupt service routine
interrupt [14] void usart_tx_isr(void)
{
    if (tx_counter)
    {
        --tx_counter;
        UDR=tx_buffer[tx_rd_index];
        if (++tx_rd_index == 5) tx_rd_index=0;
    }
}

void putchar(unsigned char c)
{
    while (tx_counter == 5);
    #asm("cli")
    if (tx_counter || ((UCSRA & (1<<5))==0))
    {
        tx_buffer[tx_wr_index]=c;
        if (++tx_wr_index == 5) tx_wr_index=0;
        ++tx_counter;
    }
    else
        UDR=c;
    #asm("sei")
}

unsigned char rx_buffer[5];     // USART Receiver buffer
unsigned char rx_counter;
bit Uart_RecvFlag;

// USART Receiver interrupt service routine
interrupt [12] void usart_rx_isr(void)
{
    unsigned char status,data;
    status = UCSRA;
    data = UDR;
    if (!Uart_RecvFlag)     // 判断是否允许接收一个新的数据包
    {
        if ((status & ((1<<4) | (1<<2) | (1<<3)))==0)
        {
            rx_buffer[rx_counter] = data;
            rx_counter++;
            switch (rx_counter)
            {
                case 1:     // 检验起始字符
                    if (data != 0xBB) rx_counter = 0;
                    break;
                case 4:     // 检验校验字
                    if (data != (rx_buffer[1]^rx_buffer[2])) rx_counter = 0;
                    break;
                case 5:     // 检验结束字符
                    rx_counter = 0;
                    if (data == 0xEE) Uart_RecvFlag = 1;
                    break;   // Uart_RecvFlag=1，表示正确接收到一个数据包
            }
        }
    }                 
}

void main(void)
{
    unsigned char channel = 0x07;
    unsigned char tx_1,tx_3;
        
    PORTA = ~(0x01<<channel);
    DDRA=0xFF;
    // USART initialization
    UCSRA=0x00;     // Communication Parameters: 8 Data, 1 Stop, No Parity
    UCSRB=0xD8;     // USART Receiver: On, USART Transmitter: On
    UCSRC=0x86;     // USART Mode: Asynchronous, USART Baud Rate: 9600
    UBRRH=0x00;
    UBRRL=0x19;
    #asm("sei")      // Global enable interrupts

    while (1)
    {
        if (Uart_RecvFlag)
        {                       // 有刚接收到数据包需要处理
            tx_1 = 0x00;
            switch (rx_buffer[1])   // 数据包处理过程
            {
                case 0xA0:
                    break;
                case 0xA1:
                    if (rx_buffer[2]>=0x00 && rx_buffer[2]<=0x07)
                    {
                        channel = rx_buffer[2];
                        PORTA = ~(0x01<<channel);
                    }    
                    else
                        tx_1 = 0x02;        
                    break;
                default:
                    tx_1 = 0x01;
                    break;
            }
            tx_3 = tx_1^channel;
            putchar(0xBB);    // 发送回送数据包
            putchar(tx_1);
            putchar(channel);
            putchar(tx_3);
            putchar(0xEE);
            Uart_RecvFlag = 0;          // 允许接收下一个数据包               
        }
    }
}