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129 lines
3.7 KiB
129 lines
3.7 KiB
//
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// Created by MightyPork on 2018/02/01.
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//
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#include "platform.h"
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#include "unit_1wire.h"
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#define OW_INTERNAL
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#include "_ow_search.h"
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#include "_ow_internal.h"
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#include "_ow_low_level.h"
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#include "_ow_commands.h"
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void ow_search_init(Unit *unit, uint8_t command, bool test_checksums)
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{
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if (unit->driver != &UNIT_1WIRE)
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trap("Wrong unit type - %s", unit->driver->name);
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assert_param(command == OW_ROM_SEARCH || command == OW_ROM_ALM_SEARCH);
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struct priv *priv = unit->data;
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struct ow_search_state *state = &priv->searchState;
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state->prev_last_fork = 64;
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memset(state->prev_code, 0, 8);
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state->status = OW_SEARCH_MORE;
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state->error = E_SUCCESS;
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state->command = command;
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state->first = true;
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state->test_checksums = test_checksums;
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}
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uint32_t ow_search_run(Unit *unit, ow_romcode_t *codes, uint32_t capacity)
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{
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if (unit->driver != &UNIT_1WIRE)
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trap("Wrong unit type - %s", unit->driver->name);
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assert_param(codes);
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struct priv *priv = unit->data;
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struct ow_search_state *state = &priv->searchState;
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if (state->status != OW_SEARCH_MORE) return 0;
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uint32_t found_devices = 0;
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while (found_devices < capacity) {
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uint8_t index = 0;
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ow_romcode_t code = {};
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int8_t last_fork = -1;
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// Start a new transaction. Devices respond to reset
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if (!ow_reset(unit)) {
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state->status = OW_SEARCH_FAILED;
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state->error = E_HW_TIMEOUT;
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goto done;
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}
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// Send the search command (SEARCH_ROM, SEARCH_ALARM)
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ow_write_u8(unit, state->command);
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uint8_t *code_byte = &code[0];
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bool p, n;
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while (index != 64) {
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// Read a bit and its complement
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p = ow_read_bit(unit);
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n = ow_read_bit(unit);
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if (!p && !n) {
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// A fork: there are devices on the bus with different bit value
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// (the bus is open-drain, in both cases one device pulls it low)
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if ((found_devices > 0 || !state->first) && index < state->prev_last_fork) {
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// earlier than the last fork, take the same turn as before
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p = ow_code_getbit(state->prev_code, index);
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if (!p) last_fork = index; // remember for future runs, 1 not explored yet
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}
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else if (index == state->prev_last_fork) {
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p = 1; // both forks are now exhausted
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}
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else { // a new fork
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last_fork = index;
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}
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}
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else if (p && n) {
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// No devices left connected - this doesn't normally happen
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state->status = OW_SEARCH_FAILED;
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state->error = E_BUS_FAULT;
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goto done;
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}
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// All devices have a matching bit here, or it was resolved in a fork
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if (p) *code_byte |= (1 << (index & 7));
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ow_write_bit(unit, p);
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index++;
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if((index & 7) == 0) {
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code_byte++;
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}
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}
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memcpy(state->prev_code, code, 8);
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if (state->test_checksums) {
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if (0 != ow_checksum(code, 8)) {
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state->status = OW_SEARCH_FAILED;
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state->error = E_CHECKSUM_MISMATCH;
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goto done;
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}
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}
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// Record a found address
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memcpy(codes[found_devices], code, 8);
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found_devices++;
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// Stop condition
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if (last_fork == -1) {
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state->status = OW_SEARCH_DONE;
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goto done;
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}
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state->prev_last_fork = last_fork;
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}
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done:
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state->first = false;
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return found_devices;
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}
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