//UART->DS18B20
//Uart转1-Wire硬件控制器程序源码例程
//HotPower@126.com 2008.3.2 于雁塔菜地
LPC_INT8U OneWire_Start (void);
LPC_INT8U OneWire_ReadWriteByte (LPC_INT8U data);
LPC_INT8U OneWire_ReadId (LPC_INT8U *pData);
LPC_INT8U OneWire_Start (void)
{
LPC_INT8U ch;
Uart1Config.BaudRate = BD9600;
Uart1Config.WordLenth = WordLength8;
Uart1Config.TwoStopBitsSelect = false;//stop=1
UART_Init(UART1);
UART_PutCharByPolling(UART1, 0xf0);
//ch=0xf0 无应答 ch=0xe0 有应答 ds18b20在线
ch = UART_GetCharByPolling(UART1);
Uart1Config.BaudRate = BD115200;
Uart1Config.WordLenth = WordLength6;
Uart1Config.TwoStopBitsSelect = false;//stop=1
UART_Init(UART1);
return ch;
}
LPC_INT8U OneWire_ReadId (LPC_INT8U *pData)
{
LPC_INT8U i, ch;
//ch=0xf0 无应答 ch=0xe0 有应答 ds18b20在线
ch = OneWire_Start();//960us
OneWire_ReadWriteByte(0x33);
for (i = 0; i < 8; i ++)
{
pData = OneWire_ReadWriteByte(0xff);//读一个字节
}
return ch;//返回结果
}
LPC_INT8U OneWire_ReadWriteByte (LPC_INT8U data)
{
LPC_INT8U i, ch;
LPC_INT8U value = 0;
for (i = 0; i < 8; i ++)
{
if (data & 1)
{
UART_PutCharByPolling(UART1, 0x3f);//1
}
else
{
UART_PutCharByPolling(UART1, 0x00);//0
}
ch = UART_GetCharByPolling(UART1);
data >>= 1;
value >>= 1;
if (ch & 0x07)//收到1T+3T个'0'为0
{
value |= 0x80;
}
}
return value;
}
void main (void)
{
char RecData, TranBuff[30];
if(SysInit() == 0)
{
// Start user program
__enable_interrupt();
UserStart();
}
__disable_interrupt();
OneWire_ReadId(TranBuff);//读18b20的器件ID=28 2D 95 1D 00 00 00 22
while(1);
}
1.读DS18B20系列码程序硬件仿真帖图
2.HotCRC计数器计算CRC8过程校验帖图
3.硬件接口电路
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