search.c

mega16连接16个DS18B20的温度计,实在厉害的东西

#include <iom16v.h>
#include <macros.h>
 unsigned char ROM_NO[8];
 unsigned char LastDiscrepancy;
 unsigned char LastFamilyDiscrepancy;
unsigned char LastDeviceFlag;
unsigned char crc8;
unsigned char tempH,tempL;
unsigned char i,nn;
//--------------------------------------------------------------------------
// Find the 'first' devices on the 1-Wire bus
// Return TRUE : device found, ROM number in ROM_NO buffer
// FALSE : no device present
//
int OWFirst(void)
{
// reset the search state
LastDiscrepancy = 0;
LastDeviceFlag = 0;
LastFamilyDiscrepancy = 0;
return OWSearch();
}
int OWNext(void)
{
// leave the search state alone
return OWSearch();
}
//--------------------------------------------------------------------------
// Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
// search state.
// Return TRUE : device found, ROM number in ROM_NO buffer
// FALSE : device not found, end of search
//
unsigned char OWSearch(void)
{
unsigned char id_bit_number;
unsigned char last_zero, rom_byte_number, search_result;
unsigned char  id_bit, cmp_id_bit;
unsigned char rom_byte_mask, search_direction;
// initialize for search
id_bit_number = 1;
last_zero = 0;
rom_byte_number = 0;
rom_byte_mask = 1;
search_result = 0;
crc8 = 0;
// if the last call was not the last one
if (!LastDeviceFlag)
{
// 1-Wire reset
if (!OWReset())
{
// reset the search
LastDiscrepancy = 0;
LastDeviceFlag = 0;
LastFamilyDiscrepancy = 0;
return 0;
}
// issue the search command
OWWriteByte(0xf0);
// loop to do the search
do
{
// read a bit and its complement
id_bit = OWReadBit();
cmp_id_bit = OWReadBit();
// check for no devices on 1-Wire
if ((id_bit == 1) && (cmp_id_bit == 1))
break;
else
{
// all devices coupled have 0 or 1
if (id_bit != cmp_id_bit)
search_direction = id_bit; // bit write value for search
else
{
// if this discrepancy if before the Last Discrepancy
// on a previous next then pick the same as last time
if (id_bit_number < LastDiscrepancy)
search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
else
// if equal to last pick 1, if not then pick 0
search_direction = (id_bit_number == LastDiscrepancy);
// if 0 was picked then record its position in LastZero
if (search_direction == 0)
{
last_zero = id_bit_number;
// check for Last discrepancy in family
if (last_zero < 9)
LastFamilyDiscrepancy = last_zero;
}
}
// set or clear the bit in the ROM byte rom_byte_number
// with mask rom_byte_mask
if (search_direction == 1)
ROM_NO[rom_byte_number] |= rom_byte_mask;
else
ROM_NO[rom_byte_number] &= ~rom_byte_mask;
// serial number search direction write bit
OWWriteBit(search_direction);
// increment the byte counter id_bit_number
// and shift the mask rom_byte_mask
id_bit_number++;
rom_byte_mask <<= 1;
// if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
if (rom_byte_mask == 0)
{
docrc8(ROM_NO[rom_byte_number]); // accumulate the CRC
rom_byte_number++;
rom_byte_mask = 1;
}
}
}
while(rom_byte_number < 8); // loop until through all ROM bytes 0-7
// if the search was successful then
if (!((id_bit_number < 65) || (crc8 != 0)))
{
// search successful so set LastDiscrepancy,LastDeviceFlag,search_result
LastDiscrepancy = last_zero;
// check for last device
if (LastDiscrepancy == 0)
LastDeviceFlag = 1;
// check for last family group
if (LastFamilyDiscrepancy == LastDiscrepancy)
LastFamilyDiscrepancy = 0;
search_result = 1;
}
}
// if no device found then reset counters so next 'search' will be like a first
if (!search_result || !ROM_NO[0])
{
LastDiscrepancy = 0;
LastDeviceFlag = 0;
LastFamilyDiscrepancy = 0;
search_result = 0;
}
return search_result;
}
static unsigned char dscrc_table[] = {
0, 94,188,226, 97, 63,221,131,194,156,126, 32,163,253, 31, 65,
157,195, 33,127,252,162, 64, 30, 95, 1,227,189, 62, 96,130,220,
35,125,159,193, 66, 28,254,160,225,191, 93, 3,128,222, 60, 98,
190,224, 2, 92,223,129, 99, 61,124, 34,192,158, 29, 67,161,255,
70, 24,250,164, 39,121,155,197,132,218, 56,102,229,187, 89, 7,
219,133,103, 57,186,228, 6, 88, 25, 71,165,251,120, 38,196,154,
101, 59,217,135, 4, 90,184,230,167,249, 27, 69,198,152,122, 36,
248,166, 68, 26,153,199, 37,123, 58,100,134,216, 91, 5,231,185,
140,210, 48,110,237,179, 81, 15, 78, 16,242,172, 47,113,147,205,
17, 79,173,243,112, 46,204,146,211,141,111, 49,178,236, 14, 80,
175,241, 19, 77,206,144,114, 44,109, 51,209,143, 12, 82,176,238,
50,108,142,208, 83, 13,239,177,240,174, 76, 18,145,207, 45,115,
202,148,118, 40,171,245, 23, 73, 8, 86,180,234,105, 55,213,139,
87, 9,235,181, 54,104,138,212,149,203, 41,119,244,170, 72, 22,
233,183, 85, 11,136,214, 52,106, 43,117,151,201, 74, 20,246,168,
116, 42,200,150, 21, 75,169,247,182,232, 10, 84,215,137,107, 53};
//--------------------------------------------------------------------------
// Calculate the CRC8 of the byte value provided with the current
// global 'crc8' value.
// Returns current global crc8 value
//
unsigned char docrc8(unsigned char value)
{
// See Application Note 27
// TEST BUILD
crc8 = dscrc_table[crc8 ^ value];
return crc8;
}
void main()
{

	port_init();
	 uart0_init();

	
		nn=OWFirst();
		
		for(i=0;i<8;i++)
		{
		putchar(ROM_NO[i]);
				}
					
		while(OWNext())
		{PORTC=~BIT(1);
         
	for(i=0;i<8;i++)
		{putchar(ROM_NO[i]);
	     
		}
};
}