498 lines
15 KiB
C
498 lines
15 KiB
C
/*
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* MIT License
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*
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* Copyright (c) 2017 David Antliff
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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/**
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* @file ds18b20.c
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*
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* Resolution is cached in the DS18B20_Info object to avoid querying the hardware
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* every time a temperature conversion is required. However this can result in the
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* cached value becoming inconsistent with the hardware value, so care must be taken.
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*
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*/
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#include <stddef.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <math.h>
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "driver/gpio.h"
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#include "esp_system.h"
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#include "esp_log.h"
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#include "ds18b20.h"
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#include "..\esp32-owb\owb.h"
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static const char * TAG = "ds18b20";
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static const int T_CONV = 750; // maximum conversion time at 12-bit resolution in milliseconds
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// Function commands
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#define DS18B20_FUNCTION_TEMP_CONVERT 0x44
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#define DS18B20_FUNCTION_SCRATCHPAD_WRITE 0x4E
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#define DS18B20_FUNCTION_SCRATCHPAD_READ 0xBE
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#define DS18B20_FUNCTION_SCRATCHPAD_COPY 0x48
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#define DS18B20_FUNCTION_EEPROM_RECALL 0xB8
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#define DS18B20_FUNCTION_POWER_SUPPLY_READ 0xB4
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/// @cond ignore
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typedef struct
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{
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uint8_t temperature[2]; // [0] is LSB, [1] is MSB
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uint8_t trigger_high;
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uint8_t trigger_low;
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uint8_t configuration;
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uint8_t reserved[3];
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uint8_t crc;
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} Scratchpad;
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/// @endcond ignore
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static void _init(DS18B20_Info * ds18b20_info, const OneWireBus * bus)
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{
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if (ds18b20_info != NULL)
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{
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ds18b20_info->bus = bus;
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memset(&ds18b20_info->rom_code, 0, sizeof(ds18b20_info->rom_code));
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ds18b20_info->use_crc = false;
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ds18b20_info->resolution = DS18B20_RESOLUTION_INVALID;
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ds18b20_info->solo = false; // assume multiple devices unless told otherwise
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ds18b20_info->init = true;
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}
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else
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{
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ESP_LOGE(TAG, "ds18b20_info is NULL");
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}
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}
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static bool _is_init(const DS18B20_Info * ds18b20_info)
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{
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bool ok = false;
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if (ds18b20_info != NULL)
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{
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if (ds18b20_info->init)
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{
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// OK
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ok = true;
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}
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else
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{
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ESP_LOGE(TAG, "ds18b20_info is not initialised");
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}
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}
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else
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{
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ESP_LOGE(TAG, "ds18b20_info is NULL");
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}
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return ok;
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}
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static bool _address_device(const DS18B20_Info * ds18b20_info)
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{
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bool present = false;
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if (_is_init(ds18b20_info))
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{
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owb_reset(ds18b20_info->bus, &present);
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if (present)
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{
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if (ds18b20_info->solo)
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{
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// if there's only one device on the bus, we can skip
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// sending the ROM code and instruct it directly
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owb_write_byte(ds18b20_info->bus, OWB_ROM_SKIP);
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}
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else
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{
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// if there are multiple devices on the bus, a Match ROM command
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// must be issued to address a specific slave
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owb_write_byte(ds18b20_info->bus, OWB_ROM_MATCH);
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owb_write_rom_code(ds18b20_info->bus, ds18b20_info->rom_code);
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}
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}
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else
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{
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ESP_LOGE(TAG, "ds18b20 device not responding");
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}
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}
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return present;
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}
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static bool _check_resolution(DS18B20_RESOLUTION resolution)
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{
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return (resolution >= DS18B20_RESOLUTION_9_BIT) && (resolution <= DS18B20_RESOLUTION_12_BIT);
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}
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static float _wait_for_conversion(DS18B20_RESOLUTION resolution)
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{
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float elapsed_time = 0.0f;
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if (_check_resolution(resolution))
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{
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int divisor = 1 << (DS18B20_RESOLUTION_12_BIT - resolution);
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ESP_LOGD(TAG, "divisor %d", divisor);
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float max_conversion_time = (float)T_CONV / (float)divisor;
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int ticks = ceil(max_conversion_time / portTICK_PERIOD_MS);
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ESP_LOGD(TAG, "wait for conversion: %.3f ms, %d ticks", max_conversion_time, ticks);
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// wait at least this maximum conversion time
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vTaskDelay(ticks);
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// TODO: measure elapsed time more accurately
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elapsed_time = ticks * portTICK_PERIOD_MS;
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}
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return elapsed_time;
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}
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static float _decode_temp(uint8_t lsb, uint8_t msb, DS18B20_RESOLUTION resolution)
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{
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float result = 0.0f;
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if (_check_resolution(resolution))
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{
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// masks to remove undefined bits from result
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static const uint8_t lsb_mask[4] = { ~0x03, ~0x02, ~0x01, ~0x00 };
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uint8_t lsb_masked = lsb_mask[resolution - DS18B20_RESOLUTION_9_BIT] & lsb;
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int16_t raw = (msb << 8) | lsb_masked;
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result = raw / 16.0f;
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}
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else
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{
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ESP_LOGE(TAG, "Unsupported resolution %d", resolution);
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}
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return result;
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}
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static size_t _min(size_t x, size_t y)
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{
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return x > y ? y : x;
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}
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static Scratchpad _read_scratchpad(const DS18B20_Info * ds18b20_info, size_t count)
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{
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count = _min(sizeof(Scratchpad), count); // avoid overflow
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Scratchpad scratchpad = {0};
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ESP_LOGD(TAG, "scratchpad read %d bytes: ", count);
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if (_address_device(ds18b20_info))
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{
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owb_write_byte(ds18b20_info->bus, DS18B20_FUNCTION_SCRATCHPAD_READ);
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owb_read_bytes(ds18b20_info->bus, (uint8_t *)&scratchpad, count);
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//esp_log_buffer_hex(TAG, &scratchpad, count);
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}
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return scratchpad;
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}
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static bool _write_scratchpad(const DS18B20_Info * ds18b20_info, const Scratchpad * scratchpad, bool verify)
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{
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bool result = false;
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// Only bytes 2, 3 and 4 (trigger and configuration) can be written.
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// All three bytes MUST be written before the next reset to avoid corruption.
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if (_is_init(ds18b20_info))
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{
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if (_address_device(ds18b20_info))
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{
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owb_write_byte(ds18b20_info->bus, DS18B20_FUNCTION_SCRATCHPAD_WRITE);
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owb_write_bytes(ds18b20_info->bus, (uint8_t *)&scratchpad->trigger_high, 3);
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ESP_LOGD(TAG, "scratchpad write 3 bytes:");
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//esp_log_buffer_hex(TAG, &scratchpad->trigger_high, 3);
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result = true;
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if (verify)
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{
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Scratchpad read = _read_scratchpad(ds18b20_info, offsetof(Scratchpad, configuration) + 1);
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if (memcmp(&scratchpad->trigger_high, &read.trigger_high, 3) != 0)
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{
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ESP_LOGE(TAG, "scratchpad verify failed: "
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"wrote {0x%02x, 0x%02x, 0x%02x}, "
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"read {0x%02x, 0x%02x, 0x%02x}",
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scratchpad->trigger_high, scratchpad->trigger_low, scratchpad->configuration,
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read.trigger_high, read.trigger_low, read.configuration);
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result = false;
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}
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}
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}
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}
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return result;
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}
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// Public API
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DS18B20_Info * ds18b20_malloc(void)
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{
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DS18B20_Info * ds18b20_info = malloc(sizeof(*ds18b20_info));
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if (ds18b20_info != NULL)
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{
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memset(ds18b20_info, 0, sizeof(*ds18b20_info));
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ESP_LOGD(TAG, "malloc %p", ds18b20_info);
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}
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else
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{
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ESP_LOGE(TAG, "malloc failed");
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}
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return ds18b20_info;
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}
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void ds18b20_free(DS18B20_Info ** ds18b20_info)
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{
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if (ds18b20_info != NULL && (*ds18b20_info != NULL))
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{
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ESP_LOGD(TAG, "free %p", *ds18b20_info);
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free(*ds18b20_info);
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*ds18b20_info = NULL;
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}
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}
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void ds18b20_init(DS18B20_Info * ds18b20_info, const OneWireBus * bus, OneWireBus_ROMCode rom_code)
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{
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if (ds18b20_info != NULL)
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{
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_init(ds18b20_info, bus);
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ds18b20_info->rom_code = rom_code;
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// read current resolution from device as it may not be power-on or factory default
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ds18b20_info->resolution = ds18b20_read_resolution(ds18b20_info);
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}
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else
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{
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ESP_LOGE(TAG, "ds18b20_info is NULL");
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}
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}
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void ds18b20_init_solo(DS18B20_Info * ds18b20_info, const OneWireBus * bus)
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{
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if (ds18b20_info != NULL)
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{
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_init(ds18b20_info, bus);
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ds18b20_info->solo = true;
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// ROM code not required
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// read current resolution from device as it may not be power-on or factory default
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ds18b20_info->resolution = ds18b20_read_resolution(ds18b20_info);
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}
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else
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{
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ESP_LOGE(TAG, "ds18b20_info is NULL");
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}
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}
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void ds18b20_use_crc(DS18B20_Info * ds18b20_info, bool use_crc)
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{
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if (_is_init(ds18b20_info))
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{
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ds18b20_info->use_crc = use_crc;
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ESP_LOGD(TAG, "use_crc %d", ds18b20_info->use_crc);
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}
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}
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bool ds18b20_set_resolution(DS18B20_Info * ds18b20_info, DS18B20_RESOLUTION resolution)
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{
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bool result = false;
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if (_is_init(ds18b20_info))
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{
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if (_check_resolution(ds18b20_info->resolution))
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{
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// read scratchpad up to and including configuration register
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Scratchpad scratchpad = _read_scratchpad(ds18b20_info,
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offsetof(Scratchpad, configuration) - offsetof(Scratchpad, temperature) + 1);
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// modify configuration register to set resolution
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uint8_t value = (((resolution - 1) & 0x03) << 5) | 0x1f;
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scratchpad.configuration = value;
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ESP_LOGD(TAG, "configuration value 0x%02x", value);
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// write bytes 2, 3 and 4 of scratchpad
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result = _write_scratchpad(ds18b20_info, &scratchpad, /* verify */ true);
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if (result)
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{
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ds18b20_info->resolution = resolution;
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ESP_LOGD(TAG, "Resolution set to %d bits", (int)resolution);
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}
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else
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{
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// Resolution change failed - update the info resolution with the value read from configuration
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ds18b20_info->resolution = ds18b20_read_resolution(ds18b20_info);
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ESP_LOGW(TAG, "Resolution consistency lost - refreshed from device: %d", ds18b20_info->resolution);
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}
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}
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else
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{
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ESP_LOGE(TAG, "Unsupported resolution %d", resolution);
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}
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}
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return result;
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}
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DS18B20_RESOLUTION ds18b20_read_resolution(DS18B20_Info * ds18b20_info)
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{
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DS18B20_RESOLUTION resolution = DS18B20_RESOLUTION_INVALID;
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if (_is_init(ds18b20_info))
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{
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// read scratchpad up to and including configuration register
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Scratchpad scratchpad = _read_scratchpad(ds18b20_info,
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offsetof(Scratchpad, configuration) - offsetof(Scratchpad, temperature) + 1);
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resolution = ((scratchpad.configuration >> 5) & 0x03) + DS18B20_RESOLUTION_9_BIT;
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if (!_check_resolution(resolution))
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{
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ESP_LOGE(TAG, "invalid resolution read from device: 0x%02x", scratchpad.configuration);
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resolution = DS18B20_RESOLUTION_INVALID;
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}
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else
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{
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ESP_LOGD(TAG, "Resolution read as %d", resolution);
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}
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}
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return resolution;
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}
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bool ds18b20_convert(const DS18B20_Info * ds18b20_info)
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{
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bool result = false;
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if (_is_init(ds18b20_info))
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{
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const OneWireBus * bus = ds18b20_info->bus;
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if (_address_device(ds18b20_info))
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{
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// initiate a temperature measurement
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owb_write_byte(bus, DS18B20_FUNCTION_TEMP_CONVERT);
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result = true;
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}
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else
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{
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ESP_LOGE(TAG, "ds18b20 device not responding");
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}
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}
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return result;
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}
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void ds18b20_convert_all(const OneWireBus * bus)
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{
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bool is_present = false;
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owb_reset(bus, &is_present);
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owb_write_byte(bus, OWB_ROM_SKIP);
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owb_write_byte(bus, DS18B20_FUNCTION_TEMP_CONVERT);
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}
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float ds18b20_wait_for_conversion(const DS18B20_Info * ds18b20_info)
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{
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float elapsed_time = 0.0f;
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if (_is_init(ds18b20_info))
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{
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elapsed_time = _wait_for_conversion(ds18b20_info->resolution);
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}
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return elapsed_time;
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}
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DS18B20_ERROR ds18b20_read_temp(const DS18B20_Info * ds18b20_info, float * value)
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{
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DS18B20_ERROR err = DS18B20_ERROR_UNKNOWN;
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if (_is_init(ds18b20_info))
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{
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const OneWireBus * bus = ds18b20_info->bus;
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if (_address_device(ds18b20_info))
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{
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// read measurement
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if (owb_write_byte(bus, DS18B20_FUNCTION_SCRATCHPAD_READ) == OWB_STATUS_OK)
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{
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err = DS18B20_OK;
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uint8_t temp_LSB = 0;
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uint8_t temp_MSB = 0;
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if (!ds18b20_info->use_crc)
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{
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// Without CRC:
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owb_read_byte(bus, &temp_LSB);
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owb_read_byte(bus, &temp_MSB);
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bool is_present = false;
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owb_reset(bus, &is_present); // terminate early
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}
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else
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{
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// with CRC:
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uint8_t buffer[9] = {0};
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owb_read_bytes(bus, buffer, 9);
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temp_LSB = buffer[0];
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temp_MSB = buffer[1];
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if (owb_crc8_bytes(0, buffer, 9) != 0)
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{
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ESP_LOGE(TAG, "CRC failed");
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temp_LSB = 0x00;
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temp_MSB = 0x80;
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err = DS18B20_ERROR_CRC;
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}
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}
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if (err == DS18B20_OK)
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{
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float temp = _decode_temp(temp_LSB, temp_MSB, ds18b20_info->resolution);
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ESP_LOGD(TAG, "temp_LSB 0x%02x, temp_MSB 0x%02x, temp %f", temp_LSB, temp_MSB, temp);
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if (value)
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{
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*value = temp;
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}
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}
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}
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else
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{
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ESP_LOGE(TAG, "owb_write_byte failed");
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err = DS18B20_ERROR_OWB;
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}
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}
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else
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{
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ESP_LOGE(TAG, "ds18b20 device not responding");
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err = DS18B20_ERROR_DEVICE;
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}
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}
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return err;
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}
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DS18B20_ERROR ds18b20_convert_and_read_temp(const DS18B20_Info * ds18b20_info, float * value)
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{
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DS18B20_ERROR err = DS18B20_ERROR_UNKNOWN;
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if (_is_init(ds18b20_info))
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{
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if (ds18b20_convert(ds18b20_info))
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{
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// wait at least maximum conversion time
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_wait_for_conversion(ds18b20_info->resolution);
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if (value)
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{
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*value = 0.0f;
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err = ds18b20_read_temp(ds18b20_info, value);
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}
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else
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{
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err = DS18B20_ERROR_NULL;
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}
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}
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}
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return err;
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}
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