327 lines
9.4 KiB
C
327 lines
9.4 KiB
C
#include "one_wire.h"
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#define OW_SLOT_A 6
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#define OW_SLOT_B 64
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#define OW_SLOT_C 60
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#define OW_SLOT_D 10
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#define OW_SLOT_E 9
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#define OW_SLOT_F 55
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#define OW_SLOT_G 10
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#define OW_SLOT_H 480
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#define OW_SLOT_I 70
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#define OW_SLOT_J 410
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#define DRIVE_DQ(x) ow->cb.drive_dq(ow->user_data, x)
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#define DELAY_US(x) ow->cb.delay_usec(ow->user_data, x)
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#define READ_DQ() ow->cb.read_dq(ow->user_data)
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static inline uint8_t onewire_op_reset(onewire_t *ow) {
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uint8_t sample_result;
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// Delay G
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DRIVE_DQ(1);
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DELAY_US(OW_SLOT_G);
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// Drive bus low, delay H
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DRIVE_DQ(0);
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DELAY_US(OW_SLOT_H);
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// Release bus, delay I
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DRIVE_DQ(1);
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DELAY_US(OW_SLOT_I);
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// Sample bus, delay J
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sample_result = READ_DQ();
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DELAY_US(OW_SLOT_J);
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return sample_result;
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}
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static inline onewire_ret_t onewire_op_write_one_bit(onewire_t *ow) {
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// Drive bus low, delay A
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DRIVE_DQ(0);
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DELAY_US(OW_SLOT_A);
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// Release bus, delay B
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DRIVE_DQ(1);
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DELAY_US(OW_SLOT_B);
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return OW_OK;
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}
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static inline onewire_ret_t onewire_op_write_zero_bit(onewire_t *ow) {
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// Drive bus low, delay C
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DRIVE_DQ(0);
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DELAY_US(OW_SLOT_C);
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// Release bus, delay D
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DRIVE_DQ(1);
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DELAY_US(OW_SLOT_D);
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return OW_OK;
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}
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static inline uint8_t onewire_op_read_bit(onewire_t *ow) {
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uint8_t sample_value;
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// Drive bus low, delay A
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DRIVE_DQ(0);
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DELAY_US(OW_SLOT_A);
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// Release bus, delay E
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DRIVE_DQ(1);
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DELAY_US(OW_SLOT_E);
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// Sample bus to read bit from slave, delay F
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sample_value = READ_DQ();
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DELAY_US(OW_SLOT_F);
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return sample_value;
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}
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uint8_t onewire_bus_reset(onewire_t *ow) {
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uint8_t device_response = onewire_op_reset(ow);
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return device_response ? 0 : 1;
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}
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static inline onewire_ret_t onewire_op_write_bit(onewire_t *ow, uint8_t bit) {
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if(bit) {
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onewire_op_write_one_bit(ow);
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}else{
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onewire_op_write_zero_bit(ow);
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}
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return OW_OK;
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}
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onewire_ret_t onrwire_bus_write_bit(onewire_t *ow, uint8_t bit) {
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if(bit) onewire_op_write_one_bit(ow);
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else onewire_op_write_zero_bit(ow);
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return OW_OK;
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}
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uint8_t onewire_bus_read_bit(onewire_t *ow) {
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return onewire_op_read_bit(ow);
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}
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onewire_ret_t onewire_bus_write_byte(onewire_t *ow, uint8_t byte) {
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for(uint8_t i = 0; i < 8; i++) {
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onewire_op_write_bit(ow, byte & 0x01);
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byte >>= 1U;
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}
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return OW_OK;
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}
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uint8_t onewire_bus_read_byte(onewire_t *ow) {
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uint8_t result = 0x00;
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for(uint8_t i = 0; i < 8; i++) {
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result >>= 1U;
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if(onewire_op_read_bit(ow)) {
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result |= 0x80U;
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}
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}
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return result;
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}
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static uint8_t dscrc_table[] = {
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0, 94,188,226, 97, 63,221,131,194,156,126, 32,163,253, 31, 65,
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157,195, 33,127,252,162, 64, 30, 95, 1,227,189, 62, 96,130,220,
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35,125,159,193, 66, 28,254,160,225,191, 93, 3,128,222, 60, 98,
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190,224, 2, 92,223,129, 99, 61,124, 34,192,158, 29, 67,161,255,
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70, 24,250,164, 39,121,155,197,132,218, 56,102,229,187, 89, 7,
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219,133,103, 57,186,228, 6, 88, 25, 71,165,251,120, 38,196,154,
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101, 59,217,135, 4, 90,184,230,167,249, 27, 69,198,152,122, 36,
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248,166, 68, 26,153,199, 37,123, 58,100,134,216, 91, 5,231,185,
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140,210, 48,110,237,179, 81, 15, 78, 16,242,172, 47,113,147,205,
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17, 79,173,243,112, 46,204,146,211,141,111, 49,178,236, 14, 80,
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175,241, 19, 77,206,144,114, 44,109, 51,209,143, 12, 82,176,238,
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50,108,142,208, 83, 13,239,177,240,174, 76, 18,145,207, 45,115,
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202,148,118, 40,171,245, 23, 73, 8, 86,180,234,105, 55,213,139,
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87, 9,235,181, 54,104,138,212,149,203, 41,119,244,170, 72, 22,
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233,183, 85, 11,136,214, 52,106, 43,117,151,201, 74, 20,246,168,
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116, 42,200,150, 21, 75,169,247,182,232, 10, 84,215,137,107, 53};
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const int FALSE = 0;
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const int TRUE = 1;
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//--------------------------------------------------------------------------
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// Calculate the CRC8 of the byte value provided with the current
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// crc8_state.
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// Returns current crc8_state value
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//
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uint8_t update_crc8(uint8_t *crc8_state, uint8_t value)
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{
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// See Application Note 27
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// TEST BUILD
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*crc8_state = dscrc_table[*crc8_state ^ value];
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return *crc8_state;
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}
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//--------------------------------------------------------------------------
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// Init device discovery on the 1-Wire bus
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// Return OW_OK
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//
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onewire_ret_t onewire_bus_search_init(onewire_t *ow)
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{
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// reset the search state
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ow->_search_state.LastDiscrepancy = 0;
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ow->_search_state.LastDeviceFlag = FALSE;
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ow->_search_state.LastFamilyDiscrepancy = 0;
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return OW_OK;
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}
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//--------------------------------------------------------------------------
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// Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
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// search state.
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// Return OW_OK : device found, ROM number in ROM_NO buffer
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// OW_ERROR : device not found, end of search
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//
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static inline onewire_ret_t onewire_bus_search(onewire_t *ow, onewire_rom_num_t *rom)
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{
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int id_bit_number;
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int last_zero, rom_byte_number, search_result;
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int id_bit, cmp_id_bit;
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uint8_t rom_byte_mask, search_direction;
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// initialize for search
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id_bit_number = 1;
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last_zero = 0;
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rom_byte_number = 0;
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rom_byte_mask = 1;
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search_result = 0;
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ow->_search_state.crc8 = 0;
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// if the last call was not the last one
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if (!ow->_search_state.LastDeviceFlag)
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{
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// 1-Wire reset
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if (!onewire_bus_reset(ow))
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{
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// reset the search
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ow->_search_state.LastDiscrepancy = 0;
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ow->_search_state.LastDeviceFlag = FALSE;
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ow->_search_state.LastFamilyDiscrepancy = 0;
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return OW_ERROR;
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}
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// issue the search command
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onewire_bus_write_byte(ow, 0xF0);
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// loop to do the search
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do
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{
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// read a bit and its complement
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id_bit = onewire_op_read_bit(ow);
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cmp_id_bit = onewire_op_read_bit(ow);
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// check for no devices on 1-wire
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if ((id_bit == 1) && (cmp_id_bit == 1))
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break;
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else
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{
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// all devices coupled have 0 or 1
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if (id_bit != cmp_id_bit)
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search_direction = id_bit; // bit write value for search
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else
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{
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// if this discrepancy if before the Last Discrepancy
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// on a previous next then pick the same as last time
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if (id_bit_number < ow->_search_state.LastDiscrepancy)
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search_direction =
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((ow->_search_state.rom_num.rom_num[rom_byte_number]
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& rom_byte_mask) > 0);
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else
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// if equal to last pick 1, if not then pick 0
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search_direction =
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(id_bit_number == ow->_search_state.LastDiscrepancy);
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// if 0 was picked then record its position in LastZero
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if (search_direction == 0)
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{
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last_zero = id_bit_number;
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// check for Last discrepancy in family
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if (last_zero < 9)
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ow->_search_state.LastFamilyDiscrepancy = last_zero;
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}
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}
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// set or clear the bit in the ROM byte rom_byte_number
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// with mask rom_byte_mask
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if (search_direction == 1)
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ow->_search_state.rom_num.rom_num[rom_byte_number]
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|= rom_byte_mask;
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else
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ow->_search_state.rom_num.rom_num[rom_byte_number]
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&= ~rom_byte_mask;
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// serial number search direction write bit
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onewire_op_write_bit(ow, search_direction);
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// increment the byte counter id_bit_number
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// and shift the mask rom_byte_mask
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id_bit_number++;
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rom_byte_mask <<= 1;
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// if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
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if (rom_byte_mask == 0)
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{
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update_crc8(&ow->_search_state.crc8,
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ow->_search_state.rom_num.rom_num[rom_byte_number]); // accumulate the CRC
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rom_byte_number++;
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rom_byte_mask = 1;
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}
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}
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}
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while(rom_byte_number < 8); // loop until through all ROM bytes 0-7
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// if the search was successful then
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if (!((id_bit_number < 65) || (ow->_search_state.crc8 != 0)))
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{
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// search successful so set LastDiscrepancy,LastDeviceFlag,search_result
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ow->_search_state.LastDiscrepancy = last_zero;
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// check for last device
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if (ow->_search_state.LastDiscrepancy == 0)
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ow->_search_state.LastDeviceFlag = TRUE;
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search_result = TRUE;
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}
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}
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// if no device found then reset counters so next 'search' will be like a first
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if (!search_result || !ow->_search_state.rom_num.rom_num[0])
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{
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ow->_search_state.LastDiscrepancy = 0;
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ow->_search_state.LastDeviceFlag = FALSE;
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ow->_search_state.LastFamilyDiscrepancy = 0;
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search_result = FALSE;
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}
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if (search_result){
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*rom = ow->_search_state.rom_num;
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return OW_OK;
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}else{
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return OW_ERROR;
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}
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}
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//--------------------------------------------------------------------------
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// Find the 'next' devices on the 1-Wire bus
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// Return OW_OK : device found, ROM number in rom buffer
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// OW_ERROR : device not found, end of search
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//
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onewire_ret_t onewire_bus_search_nextdev(onewire_t *ow, onewire_rom_num_t *rom)
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{
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// leave the search state alone
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return onewire_bus_search(ow, rom);
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}
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