【发布时间】：2009-12-15 20:22:07
【问题描述】：
我已经在下面定义了这些函数，当我询问 Device_ID 函数时，例如 家庭代码，我只得到FF（应该是28），实际上我得到了家庭代码，48位串行和crc 8位都是“一”。似乎检测从设备功能正常工作......如果我连接从设备，他说我在这里，如果我把它拿走......没有设备存在。我在 1wire 上也有一个 5kohm 的上拉电阻。
而且我不知道为什么我的 Device_ID 不起作用，所以我的问题是为什么它不起作用！？你能在这段代码中看到任何错误吗（我使用的是 PIC 18F87J50 和一个 DS18B20）：
我在 Main 中的声明：
OSCTUNEbits.PLLEN = 1;
Init_Registers();
Init_Settings();
Init_Ports();
Init_Glcd();
Detect_Slave_Device();
Device_ID( 0x33 );
用到的函数：
void Detect_Slave_Device(void){
uint8_t value;
OW_reset_pulse();
if (OW_reset_pulse())
{
Display_Cls();
Display_StringAt("No Device Present!",5,6);
Delay_1sec();
Delay_1sec();
} else {
Display_Cls();
Display_StringAt("Device Present!",5,6);
Delay_1sec();
Delay_1sec(); }}
uint8_t OW_reset_pulse(void){
uint8_t presence_detect;
drive_OW_low(); // Drive the bus low
Delay_us(200); // Delay at least 480 microsecond (us)
Delay_us(200);
Delay_us(85);
drive_OW_high (); // Release the bus
// Here should the client drive low
Delay_us(50); // Delay 50 microsecond (us)
presence_detect = read_OW(); // Sample for presence pulse from slave
Delay_us(200); // Delay 435 microsecond (us)
Delay_us(200);
Delay_us(35);
drive_OW_high (); // Release the bus
return presence_detect;}
void drive_OW_low (void){
LATHbits.LATH0 = 0;
TRISHbits.TRISH0 = 0; }// Output
void drive_OW_high (void){
LATHbits.LATH0 = 0;
TRISHbits.TRISH0 = 1;} // Input
uint8_t read_OW (void){
unsigned char read_data=0;
TRISHbits.TRISH0 = 1;
if (1 == PORTHbits.RH0)
read_data = 1;
else
read_data = 0;
return read_data;}
现在还有一些重要的 device_id：
void Device_ID( uint8_t command ){
uint8_t loop, family, checksum, ROM_CODE[8]; // 1 byte CRC, 6 bytes SERIAL, 1 byte Family code
static char container[1];
OW_reset_pulse();
OW_write_byte( 0x33 ); // READ ROM COMMAND DS18B20
for(loop = 0; loop < 9; loop++) // 1 byte in per time = 64-bits
{
ROM_CODE[loop] = OW_read_byte();
}
family = ROM_CODE[1];
checksum = ROM_CODE[8];
And so on = Print MY VALUES ->
void OW_write_byte (uint8_t write_data){
uint8_t loop;
for (loop = 0; loop < 8; loop++)
{
OW_write_bit(write_data & 0x01); //Sending LS-bit first
write_data >>= 1; // shift the data byte for the next bit to send
} }
void OW_write_bit (uint8_t write_bit){
if (write_bit) // Write 1 time slot
{
Brakepoint(); // 1 us
//writing a bit '1'
drive_OW_low(); // Drive the bus low
Delay_us(6); // Delay 6 microsecond (us)
drive_OW_high (); // Release the bus
Delay_us(64);; // Delay 64 microsecond (us)
}
else // Write 0 time slot
{
Brakepoint(); // 1 us
//writing a bit '0'
drive_OW_low(); // Drive the bus low
Delay_us(65); // Delay 65 microsecond (us)
drive_OW_high (); // Release the bus
Delay_us(10); // Delay 10 microsecond for recovery (us)
}}
uint8_t OW_read_byte (void)
uint8_t loop, result=0;
for (loop = 0; loop < 8; loop++)
{
result >>= 1; // shift the result to get it ready for the next bit to receive
if (OW_read_bit())
result |= 0x80; // if result is one, then set MS-bit
}
return result; }
uint8_t OW_read_bit (void){
uint8_t read_data; // Reading a bit
Brakepoint(); // 1 us
drive_OW_low(); // Drive the bus low
Delay_us(6); // delay 6 microsecond (us)
drive_OW_high (); // Release the bus
Delay_us(9); // delay 9 microsecond (us)
read_data = read_OW(); //Read the status of OW_PIN
Delay_us(55); // delay 55 microsecond (us)
return read_data;}
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