1-Wire bus search algorithm, new C implementation
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#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <inttypes.h>
#include "ow_search.h"
// ----------- DEMO -----------------
int main(void)
{
// The search algorithm stores its internal state in a struct.
// This allows calling it repeatedly if there are more devices
// than could fit in the address buffer.
struct ow_search_state search_state;
ow_search_init(&search_state, 0xF0 /* SEARCH_ROM */, false /* checksums */);
// Buffer for the found addresses - can have up to 65536 rows
// Keep in mind that each address uses 8 bytes
#define CODE_BUFFER_LEN 8
ow_romcode_t addresses[CODE_BUFFER_LEN];
// The algorithm stores its return value in the status field,
// we can loop until it becomes OW_SEARCH_DONE or OW_SEARCH_FAILED
while (search_state.status == OW_SEARCH_MORE) {
// Perform a run of the algorithm
uint16_t count = ow_search_run(&search_state, addresses, CODE_BUFFER_LEN);
// Do something with the found addresses
printf("Found %d addresses, status %d\n", count, search_state.status);
for (int i = 0; i < count; i++) {
printf("> ");
for (int j = 0; j < 8; j++) {
printf("%02x ", addresses[i][j]);
}
uint64_t numeric = ow_romcode_to_u64(addresses[i]);
printf(" (0x%016"PRIx64")\n", numeric);
}
printf("\n");
}
return 0;
}
// ------------ SIMULATOR ---------------
// A simple 1-wire bus simulation following the real behavior of bus devices
// in the search operation.
struct owunit {
ow_romcode_t romcode;
bool selected;
uint8_t rompos;
int state;
};
#define UNITS_COUNT 13
struct owunit units[UNITS_COUNT] = {
{.romcode = {0b00000000}},//00
{.romcode = {0b00000001}},//01
{.romcode = {0b00010001}},//11
{.romcode = {0b00110001}},//31
{.romcode = {0b00110101}},//35
{.romcode = {0b01010001}},//51
{.romcode = {0b10000000}},//80
{.romcode = {0b10101010}},//aa
{.romcode = {0b11110101}},//f5
{.romcode = {0b11110111}},//f7
{.romcode = {0xFF,0x00,0xFF,0x00,0x55,0x00,0xAA,0x00}},
{.romcode = {0x12,0x34,0x56,0x78,0x9a,0xbc,0xde,0xf0}},
{.romcode = {0x10,0x76,0xc7,0x04,0x01,0x08,0x00,0x71}}, // this is from a real 1-wire thermometer - checksum should be OK
};
void rom_device_reset(struct owunit *device)
{
device->rompos = 0;
device->state = 0;
device->selected = true;
}
bool rom_device_read(struct owunit *device)
{
if (!device->selected) return true;
bool res = 0;
if (device->state == 0) {
device->state++;
res = ow_code_getbit(device->romcode, device->rompos);
return res;
}
if (device->state == 1) {
device->state++;
res = !ow_code_getbit(device->romcode, device->rompos);
return res;
}
return res;
}
void rom_device_write(struct owunit *device, bool selectedbit)
{
if (!device->selected) return;
if (ow_code_getbit(device->romcode, device->rompos) != selectedbit) {
device->selected = false;
}
else {
device->rompos++;
device->state = 0;
}
}
bool ow_reset(void)
{
for (int i = 0; i < UNITS_COUNT; ++i) {
rom_device_reset(&units[i]);
}
return (UNITS_COUNT > 0);
}
bool ow_read_bit(void)
{
bool bus = 1;
for (int i = 0; i < UNITS_COUNT; ++i) {
bus &= rom_device_read(&units[i]);
}
return bus;
}
void ow_write_bit(bool value)
{
for (int i = 0; i < UNITS_COUNT; ++i) {
rom_device_write(&units[i], value);
}
}
void ow_write_u8(uint8_t value)
{
(void) value;
// Dummy, do nothing
}