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esp-geiger/components/esp32-ds18b20/ds18b20.c

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/*
* MIT License
*
* Copyright (c) 2017-2019 David Antliff
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
/**
* @file ds18b20.c
*
* Resolution is cached in the DS18B20_Info object to avoid querying the hardware
* every time a temperature conversion is required. However this can result in the
* cached value becoming inconsistent with the hardware value, so care must be taken.
*
*/
#include <stddef.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <math.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#include "esp_system.h"
#include "esp_log.h"
#include "ds18b20.h"
#include "owb.h"
static const char * TAG = "ds18b20";
static const int T_CONV = 750; // maximum conversion time at 12-bit resolution in milliseconds
// Function commands
#define DS18B20_FUNCTION_TEMP_CONVERT 0x44 ///< Initiate a single temperature conversion
#define DS18B20_FUNCTION_SCRATCHPAD_WRITE 0x4E ///< Write 3 bytes of data to the device scratchpad at positions 2, 3 and 4
#define DS18B20_FUNCTION_SCRATCHPAD_READ 0xBE ///< Read 9 bytes of data (including CRC) from the device scratchpad
#define DS18B20_FUNCTION_SCRATCHPAD_COPY 0x48 ///< Copy the contents of the scratchpad to the device EEPROM
#define DS18B20_FUNCTION_EEPROM_RECALL 0xB8 ///< Restore alarm trigger values and configuration data from EEPROM to the scratchpad
#define DS18B20_FUNCTION_POWER_SUPPLY_READ 0xB4 ///< Determine if a device is using parasitic power
/// @cond ignore
typedef struct
{
uint8_t temperature[2]; // [0] is LSB, [1] is MSB
uint8_t trigger_high;
uint8_t trigger_low;
uint8_t configuration;
uint8_t reserved[3];
uint8_t crc;
} __attribute__((packed)) Scratchpad;
/// @endcond ignore
static void _init(DS18B20_Info * ds18b20_info, const OneWireBus * bus)
{
if (ds18b20_info != NULL)
{
ds18b20_info->bus = bus;
memset(&ds18b20_info->rom_code, 0, sizeof(ds18b20_info->rom_code));
ds18b20_info->use_crc = false;
ds18b20_info->resolution = DS18B20_RESOLUTION_INVALID;
ds18b20_info->solo = false; // assume multiple devices unless told otherwise
ds18b20_info->init = true;
}
else
{
ESP_LOGE(TAG, "ds18b20_info is NULL");
}
}
static bool _is_init(const DS18B20_Info * ds18b20_info)
{
bool ok = false;
if (ds18b20_info != NULL)
{
if (ds18b20_info->init)
{
// OK
ok = true;
}
else
{
ESP_LOGE(TAG, "ds18b20_info is not initialised");
}
}
else
{
ESP_LOGE(TAG, "ds18b20_info is NULL");
}
return ok;
}
static bool _address_device(const DS18B20_Info * ds18b20_info)
{
bool present = false;
if (_is_init(ds18b20_info))
{
owb_reset(ds18b20_info->bus, &present);
if (present)
{
if (ds18b20_info->solo)
{
// if there's only one device on the bus, we can skip
// sending the ROM code and instruct it directly
owb_write_byte(ds18b20_info->bus, OWB_ROM_SKIP);
}
else
{
// if there are multiple devices on the bus, a Match ROM command
// must be issued to address a specific slave
owb_write_byte(ds18b20_info->bus, OWB_ROM_MATCH);
owb_write_rom_code(ds18b20_info->bus, ds18b20_info->rom_code);
}
}
else
{
ESP_LOGE(TAG, "ds18b20 device not responding");
}
}
return present;
}
static bool _check_resolution(DS18B20_RESOLUTION resolution)
{
return (resolution >= DS18B20_RESOLUTION_9_BIT) && (resolution <= DS18B20_RESOLUTION_12_BIT);
}
static float _wait_for_duration(DS18B20_RESOLUTION resolution)
{
int64_t start_time = esp_timer_get_time();
if (_check_resolution(resolution))
{
int divisor = 1 << (DS18B20_RESOLUTION_12_BIT - resolution);
ESP_LOGD(TAG, "divisor %d", divisor);
float max_conversion_time = (float)T_CONV / (float)divisor;
int ticks = ceil(max_conversion_time / portTICK_PERIOD_MS);
ESP_LOGD(TAG, "wait for conversion: %.3f ms, %d ticks", max_conversion_time, ticks);
// wait at least this maximum conversion time
vTaskDelay(ticks);
}
int64_t end_time = esp_timer_get_time();
return (float)(end_time - start_time) / 1000000.0f;
}
static float _wait_for_device_signal(const DS18B20_Info * ds18b20_info)
{
float elapsed_time = 0.0f;
if (_check_resolution(ds18b20_info->resolution))
{
int divisor = 1 << (DS18B20_RESOLUTION_12_BIT - ds18b20_info->resolution);
// allow for 10% overtime
float max_conversion_time = (float)T_CONV / (float)divisor * 1.1;
int max_conversion_ticks = ceil(max_conversion_time / portTICK_PERIOD_MS);
ESP_LOGD(TAG, "wait for conversion: max %.0f ms, %d ticks", max_conversion_time, max_conversion_ticks);
// wait for conversion to complete - all devices will pull bus low once complete
TickType_t start_ticks = xTaskGetTickCount();
TickType_t duration_ticks = 0;
uint8_t status = 0;
do
{
vTaskDelay(1);
owb_read_bit(ds18b20_info->bus, &status);
duration_ticks = xTaskGetTickCount() - start_ticks;
} while (status == 0 && duration_ticks < max_conversion_ticks);
elapsed_time = duration_ticks * portTICK_PERIOD_MS;
if (duration_ticks >= max_conversion_ticks)
{
ESP_LOGW(TAG, "conversion timed out");
}
else
{
ESP_LOGD(TAG, "conversion took at most %.0f ms", elapsed_time);
}
}
return elapsed_time;
}
static float _decode_temp(uint8_t lsb, uint8_t msb, DS18B20_RESOLUTION resolution)
{
float result = 0.0f;
if (_check_resolution(resolution))
{
// masks to remove undefined bits from result
static const uint8_t lsb_mask[4] = { ~0x07, ~0x03, ~0x01, ~0x00 };
uint8_t lsb_masked = lsb_mask[resolution - DS18B20_RESOLUTION_9_BIT] & lsb;
int16_t raw = (msb << 8) | lsb_masked;
result = raw / 16.0f;
}
else
{
ESP_LOGE(TAG, "Unsupported resolution %d", resolution);
}
return result;
}
static size_t _min(size_t x, size_t y)
{
return x > y ? y : x;
}
static DS18B20_ERROR _read_scratchpad(const DS18B20_Info * ds18b20_info, Scratchpad * scratchpad, size_t count)
{
// If CRC is enabled, regardless of count, read the entire scratchpad and verify the CRC,
// otherwise read up to the scratchpad size, or count, whichever is smaller.
if (!scratchpad) {
return DS18B20_ERROR_NULL;
}
DS18B20_ERROR err = DS18B20_ERROR_UNKNOWN;
if (ds18b20_info->use_crc)
{
count = sizeof(Scratchpad);
}
count = _min(sizeof(Scratchpad), count); // avoid reading past end of scratchpad
ESP_LOGD(TAG, "scratchpad read: CRC %d, count %d", ds18b20_info->use_crc, count);
if (_address_device(ds18b20_info))
{
// read scratchpad
if (owb_write_byte(ds18b20_info->bus, DS18B20_FUNCTION_SCRATCHPAD_READ) == OWB_STATUS_OK)
{
if (owb_read_bytes(ds18b20_info->bus, (uint8_t *)scratchpad, count) == OWB_STATUS_OK)
{
ESP_LOG_BUFFER_HEX_LEVEL(TAG, scratchpad, count, ESP_LOG_DEBUG);
err = DS18B20_OK;
if (!ds18b20_info->use_crc)
{
// Without CRC, or partial read:
ESP_LOGD(TAG, "No CRC check");
bool is_present = false;
owb_reset(ds18b20_info->bus, &is_present); // terminate early
}
else
{
// With CRC:
if (owb_crc8_bytes(0, (uint8_t *)scratchpad, sizeof(*scratchpad)) != 0)
{
ESP_LOGE(TAG, "CRC failed");
err = DS18B20_ERROR_CRC;
}
else
{
ESP_LOGD(TAG, "CRC ok");
}
}
}
else
{
ESP_LOGE(TAG, "owb_read_bytes failed");
err = DS18B20_ERROR_OWB;
}
}
else
{
ESP_LOGE(TAG, "owb_write_byte failed");
err = DS18B20_ERROR_OWB;
}
}
else
{
err = DS18B20_ERROR_DEVICE;
}
return err;
}
static bool _write_scratchpad(const DS18B20_Info * ds18b20_info, const Scratchpad * scratchpad, bool verify)
{
bool result = false;
// Only bytes 2, 3 and 4 (trigger and configuration) can be written.
// All three bytes MUST be written before the next reset to avoid corruption.
if (_is_init(ds18b20_info))
{
if (_address_device(ds18b20_info))
{
ESP_LOGD(TAG, "scratchpad write 3 bytes:");
ESP_LOG_BUFFER_HEX_LEVEL(TAG, &scratchpad->trigger_high, 3, ESP_LOG_DEBUG);
owb_write_byte(ds18b20_info->bus, DS18B20_FUNCTION_SCRATCHPAD_WRITE);
owb_write_bytes(ds18b20_info->bus, (uint8_t *)&scratchpad->trigger_high, 3);
result = true;
if (verify)
{
Scratchpad read = {0};
if (_read_scratchpad(ds18b20_info, &read, offsetof(Scratchpad, configuration) + 1) == DS18B20_OK)
{
if (memcmp(&scratchpad->trigger_high, &read.trigger_high, 3) != 0)
{
ESP_LOGE(TAG, "scratchpad verify failed: "
"wrote {0x%02x, 0x%02x, 0x%02x}, "
"read {0x%02x, 0x%02x, 0x%02x}",
scratchpad->trigger_high, scratchpad->trigger_low, scratchpad->configuration,
read.trigger_high, read.trigger_low, read.configuration);
result = false;
}
}
else
{
ESP_LOGE(TAG, "read scratchpad failed");
result = false;
}
}
}
}
return result;
}
// Public API
DS18B20_Info * ds18b20_malloc(void)
{
DS18B20_Info * ds18b20_info = malloc(sizeof(*ds18b20_info));
if (ds18b20_info != NULL)
{
memset(ds18b20_info, 0, sizeof(*ds18b20_info));
ESP_LOGD(TAG, "malloc %p", ds18b20_info);
}
else
{
ESP_LOGE(TAG, "malloc failed");
}
return ds18b20_info;
}
void ds18b20_free(DS18B20_Info ** ds18b20_info)
{
if (ds18b20_info != NULL && (*ds18b20_info != NULL))
{
ESP_LOGD(TAG, "free %p", *ds18b20_info);
free(*ds18b20_info);
*ds18b20_info = NULL;
}
}
void ds18b20_init(DS18B20_Info * ds18b20_info, const OneWireBus * bus, OneWireBus_ROMCode rom_code)
{
if (ds18b20_info != NULL)
{
_init(ds18b20_info, bus);
ds18b20_info->rom_code = rom_code;
// read current resolution from device as it may not be power-on or factory default
ds18b20_info->resolution = ds18b20_read_resolution(ds18b20_info);
}
else
{
ESP_LOGE(TAG, "ds18b20_info is NULL");
}
}
void ds18b20_init_solo(DS18B20_Info * ds18b20_info, const OneWireBus * bus)
{
if (ds18b20_info != NULL)
{
_init(ds18b20_info, bus);
ds18b20_info->solo = true;
// ROM code not required
// read current resolution from device as it may not be power-on or factory default
ds18b20_info->resolution = ds18b20_read_resolution(ds18b20_info);
}
else
{
ESP_LOGE(TAG, "ds18b20_info is NULL");
}
}
void ds18b20_use_crc(DS18B20_Info * ds18b20_info, bool use_crc)
{
if (_is_init(ds18b20_info))
{
ds18b20_info->use_crc = use_crc;
ESP_LOGD(TAG, "use_crc %d", ds18b20_info->use_crc);
}
}
bool ds18b20_set_resolution(DS18B20_Info * ds18b20_info, DS18B20_RESOLUTION resolution)
{
bool result = false;
if (_is_init(ds18b20_info))
{
if (_check_resolution(ds18b20_info->resolution))
{
// read scratchpad up to and including configuration register
Scratchpad scratchpad = {0};
_read_scratchpad(ds18b20_info, &scratchpad,
offsetof(Scratchpad, configuration) - offsetof(Scratchpad, temperature) + 1);
// modify configuration register to set resolution
uint8_t value = (((resolution - 1) & 0x03) << 5) | 0x1f;
scratchpad.configuration = value;
ESP_LOGD(TAG, "configuration value 0x%02x", value);
// write bytes 2, 3 and 4 of scratchpad
result = _write_scratchpad(ds18b20_info, &scratchpad, /* verify */ true);
if (result)
{
ds18b20_info->resolution = resolution;
ESP_LOGD(TAG, "Resolution set to %d bits", (int)resolution);
}
else
{
// Resolution change failed - update the info resolution with the value read from configuration
ds18b20_info->resolution = ds18b20_read_resolution(ds18b20_info);
ESP_LOGW(TAG, "Resolution consistency lost - refreshed from device: %d", ds18b20_info->resolution);
}
}
else
{
ESP_LOGE(TAG, "Unsupported resolution %d", resolution);
}
}
return result;
}
DS18B20_RESOLUTION ds18b20_read_resolution(DS18B20_Info * ds18b20_info)
{
DS18B20_RESOLUTION resolution = DS18B20_RESOLUTION_INVALID;
if (_is_init(ds18b20_info))
{
// read scratchpad up to and including configuration register
Scratchpad scratchpad = {0};
_read_scratchpad(ds18b20_info, &scratchpad,
offsetof(Scratchpad, configuration) - offsetof(Scratchpad, temperature) + 1);
resolution = ((scratchpad.configuration >> 5) & 0x03) + DS18B20_RESOLUTION_9_BIT;
if (!_check_resolution(resolution))
{
ESP_LOGE(TAG, "invalid resolution read from device: 0x%02x", scratchpad.configuration);
resolution = DS18B20_RESOLUTION_INVALID;
}
else
{
ESP_LOGD(TAG, "Resolution read as %d", resolution);
}
}
return resolution;
}
bool ds18b20_convert(const DS18B20_Info * ds18b20_info)
{
bool result = false;
if (_is_init(ds18b20_info))
{
const OneWireBus * bus = ds18b20_info->bus;
if (_address_device(ds18b20_info))
{
// initiate a temperature measurement
owb_write_byte(bus, DS18B20_FUNCTION_TEMP_CONVERT);
result = true;
}
else
{
ESP_LOGE(TAG, "ds18b20 device not responding");
}
}
return result;
}
void ds18b20_convert_all(const OneWireBus * bus)
{
if (bus)
{
bool is_present = false;
owb_reset(bus, &is_present);
owb_write_byte(bus, OWB_ROM_SKIP);
owb_write_byte(bus, DS18B20_FUNCTION_TEMP_CONVERT);
owb_set_strong_pullup(bus, true);
}
else
{
ESP_LOGE(TAG, "bus is NULL");
}
}
float ds18b20_wait_for_conversion(const DS18B20_Info * ds18b20_info)
{
float elapsed_time = 0.0f;
if (_is_init(ds18b20_info))
{
if (ds18b20_info->bus->use_parasitic_power)
{
// in parasitic mode, devices cannot signal when they are complete,
// so use the datasheet values to wait for a duration.
elapsed_time = _wait_for_duration(ds18b20_info->resolution);
}
else
{
// wait for the device(s) to indicate the conversion is complete
elapsed_time = _wait_for_device_signal(ds18b20_info);
}
}
return elapsed_time;
}
DS18B20_ERROR ds18b20_read_temp(const DS18B20_Info * ds18b20_info, float * value)
{
DS18B20_ERROR err = DS18B20_ERROR_UNKNOWN;
if (_is_init(ds18b20_info))
{
uint8_t temp_LSB = 0x00;
uint8_t temp_MSB = 0x80;
Scratchpad scratchpad = {0};
if ((err = _read_scratchpad(ds18b20_info, &scratchpad, 2)) == DS18B20_OK)
{
temp_LSB = scratchpad.temperature[0];
temp_MSB = scratchpad.temperature[1];
}
// https://github.com/cpetrich/counterfeit_DS18B20#solution-to-the-85-c-problem
if (scratchpad.reserved[1] == 0x0c && temp_MSB == 0x05 && temp_LSB == 0x50)
{
ESP_LOGE(TAG, "Read power-on value (85.0)");
err = DS18B20_ERROR_DEVICE;
}
float temp = _decode_temp(temp_LSB, temp_MSB, ds18b20_info->resolution);
ESP_LOGD(TAG, "temp_LSB 0x%02x, temp_MSB 0x%02x, temp %f", temp_LSB, temp_MSB, temp);
if (value)
{
*value = temp;
}
}
return err;
}
DS18B20_ERROR ds18b20_convert_and_read_temp(const DS18B20_Info * ds18b20_info, float * value)
{
DS18B20_ERROR err = DS18B20_ERROR_UNKNOWN;
if (_is_init(ds18b20_info))
{
if (ds18b20_convert(ds18b20_info))
{
// wait at least maximum conversion time
ds18b20_wait_for_conversion(ds18b20_info);
if (value)
{
*value = 0.0f;
err = ds18b20_read_temp(ds18b20_info, value);
}
else
{
err = DS18B20_ERROR_NULL;
}
}
}
return err;
}
DS18B20_ERROR ds18b20_check_for_parasite_power(const OneWireBus * bus, bool * present)
{
DS18B20_ERROR err = DS18B20_ERROR_UNKNOWN;
ESP_LOGD(TAG, "ds18b20_check_for_parasite_power");
if (bus) {
bool reset_present;
if ((err = owb_reset(bus, &reset_present)) == DS18B20_OK)
{
ESP_LOGD(TAG, "owb_reset OK");
if ((err = owb_write_byte(bus, OWB_ROM_SKIP)) == DS18B20_OK)
{
ESP_LOGD(TAG, "owb_write_byte(ROM_SKIP) OK");
if ((err = owb_write_byte(bus, DS18B20_FUNCTION_POWER_SUPPLY_READ)) == DS18B20_OK)
{
// Parasitic-powered devices will pull the bus low during read time slot
ESP_LOGD(TAG, "owb_write_byte(POWER_SUPPLY_READ) OK");
uint8_t value = 0;
if ((err = owb_read_bit(bus, &value)) == DS18B20_OK)
{
ESP_LOGD(TAG, "owb_read_bit OK: 0x%02x", value);
if (present)
{
*present = !(bool)(value & 0x01u);
}
}
}
}
}
}
else
{
ESP_LOGE(TAG, "bus is NULL");
err = DS18B20_ERROR_NULL;
}
return err;
}