esphome/esphome/components/dallas/esp_one_wire.cpp
2020-07-14 18:45:42 +02:00

217 lines
5.5 KiB
C++

#include "esp_one_wire.h"
#include "esphome/core/log.h"
#include "esphome/core/helpers.h"
namespace esphome {
namespace dallas {
static const char *TAG = "dallas.one_wire";
const uint8_t ONE_WIRE_ROM_SELECT = 0x55;
const int ONE_WIRE_ROM_SEARCH = 0xF0;
ESPOneWire::ESPOneWire(GPIOPin *pin) : pin_(pin) {}
bool HOT ICACHE_RAM_ATTR ESPOneWire::reset() {
uint8_t retries = 125;
// Wait for communication to clear
this->pin_->pin_mode(INPUT_PULLUP);
do {
if (--retries == 0)
return false;
delayMicroseconds(2);
} while (!this->pin_->digital_read());
// Send 480µs LOW TX reset pulse
this->pin_->pin_mode(OUTPUT);
this->pin_->digital_write(false);
delayMicroseconds(480);
// Switch into RX mode, letting the pin float
this->pin_->pin_mode(INPUT_PULLUP);
// after 15µs-60µs wait time, responder pulls low for 60µs-240µs
// let's have 70µs just in case
delayMicroseconds(70);
bool r = !this->pin_->digital_read();
delayMicroseconds(410);
return r;
}
void HOT ICACHE_RAM_ATTR ESPOneWire::write_bit(bool bit) {
// Initiate write/read by pulling low.
this->pin_->pin_mode(OUTPUT);
this->pin_->digital_write(false);
// bus sampled within 15µs and 60µs after pulling LOW.
if (bit) {
// pull high/release within 15µs
delayMicroseconds(10);
this->pin_->digital_write(true);
// in total minimum of 60µs long
delayMicroseconds(55);
} else {
// continue pulling LOW for at least 60µs
delayMicroseconds(65);
this->pin_->digital_write(true);
// grace period, 1µs recovery time
delayMicroseconds(5);
}
}
bool HOT ICACHE_RAM_ATTR ESPOneWire::read_bit() {
// Initiate read slot by pulling LOW for at least 1µs
this->pin_->pin_mode(OUTPUT);
this->pin_->digital_write(false);
delayMicroseconds(3);
// release bus, we have to sample within 15µs of pulling low
this->pin_->pin_mode(INPUT_PULLUP);
delayMicroseconds(10);
bool r = this->pin_->digital_read();
// read time slot at least 60µs long + 1µs recovery time between slots
delayMicroseconds(53);
return r;
}
void ICACHE_RAM_ATTR ESPOneWire::write8(uint8_t val) {
for (uint8_t i = 0; i < 8; i++) {
this->write_bit(bool((1u << i) & val));
}
}
void ICACHE_RAM_ATTR ESPOneWire::write64(uint64_t val) {
for (uint8_t i = 0; i < 64; i++) {
this->write_bit(bool((1ULL << i) & val));
}
}
uint8_t ICACHE_RAM_ATTR ESPOneWire::read8() {
uint8_t ret = 0;
for (uint8_t i = 0; i < 8; i++) {
ret |= (uint8_t(this->read_bit()) << i);
}
return ret;
}
uint64_t ICACHE_RAM_ATTR ESPOneWire::read64() {
uint64_t ret = 0;
for (uint8_t i = 0; i < 8; i++) {
ret |= (uint64_t(this->read_bit()) << i);
}
return ret;
}
void ICACHE_RAM_ATTR ESPOneWire::select(uint64_t address) {
this->write8(ONE_WIRE_ROM_SELECT);
this->write64(address);
}
void ICACHE_RAM_ATTR ESPOneWire::reset_search() {
this->last_discrepancy_ = 0;
this->last_device_flag_ = false;
this->last_family_discrepancy_ = 0;
this->rom_number_ = 0;
}
uint64_t HOT ICACHE_RAM_ATTR ESPOneWire::search() {
if (this->last_device_flag_) {
return 0u;
}
if (!this->reset()) {
// Reset failed
this->reset_search();
return 0u;
}
uint8_t id_bit_number = 1;
uint8_t last_zero = 0;
uint8_t rom_byte_number = 0;
bool search_result = false;
uint8_t rom_byte_mask = 1;
// Initiate search
this->write8(ONE_WIRE_ROM_SEARCH);
do {
// read bit
bool id_bit = this->read_bit();
// read its complement
bool cmp_id_bit = this->read_bit();
if (id_bit && cmp_id_bit)
// No devices participating in search
break;
bool branch;
if (id_bit != cmp_id_bit) {
// only chose one branch, the other one doesn't have any devices.
branch = id_bit;
} else {
// there are devices with both 0s and 1s at this bit
if (id_bit_number < this->last_discrepancy_) {
branch = (this->rom_number8_()[rom_byte_number] & rom_byte_mask) > 0;
} else {
branch = id_bit_number == this->last_discrepancy_;
}
if (!branch) {
last_zero = id_bit_number;
if (last_zero < 9) {
this->last_discrepancy_ = last_zero;
}
}
}
if (branch)
// set bit
this->rom_number8_()[rom_byte_number] |= rom_byte_mask;
else
// clear bit
this->rom_number8_()[rom_byte_number] &= ~rom_byte_mask;
// choose/announce branch
this->write_bit(branch);
id_bit_number++;
rom_byte_mask <<= 1;
if (rom_byte_mask == 0u) {
// go to next byte
rom_byte_number++;
rom_byte_mask = 1;
}
} while (rom_byte_number < 8); // loop through all bytes
if (id_bit_number >= 65) {
this->last_discrepancy_ = last_zero;
if (this->last_discrepancy_ == 0)
// we're at root and have no choices left, so this was the last one.
this->last_device_flag_ = true;
search_result = true;
}
search_result = search_result && (this->rom_number8_()[0] != 0);
if (!search_result) {
this->reset_search();
return 0u;
}
return this->rom_number_;
}
std::vector<uint64_t> ICACHE_RAM_ATTR ESPOneWire::search_vec() {
std::vector<uint64_t> res;
this->reset_search();
uint64_t address;
while ((address = this->search()) != 0u)
res.push_back(address);
return res;
}
void ICACHE_RAM_ATTR ESPOneWire::skip() {
this->write8(0xCC); // skip ROM
}
GPIOPin *ESPOneWire::get_pin() { return this->pin_; }
uint8_t ICACHE_RAM_ATTR *ESPOneWire::rom_number8_() { return reinterpret_cast<uint8_t *>(&this->rom_number_); }
} // namespace dallas
} // namespace esphome