David Antliff
8 years ago
6 changed files with 617 additions and 312 deletions
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#include <stddef.h> |
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#include <stdbool.h> |
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#include <inttypes.h> |
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#include <string.h> |
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#include "esp_log.h" |
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#include "sdkconfig.h" |
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#include "driver/gpio.h" |
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#include "owb.h" |
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#define TAG "owb" |
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struct _OneWireBus_Timing |
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{ |
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int A, B, C, D, E, F, G, H, I, J; |
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}; |
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// 1-Wire timing delays (standard) in ticks (quarter-microseconds).
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static const struct _OneWireBus_Timing _StandardTiming = { |
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6 * 4, |
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64 * 4, |
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60 * 4, |
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10 * 4, |
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9 * 4, |
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55 * 4, |
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0, // G
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480 * 4, // H
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70 * 4, // I
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410 * 4, // J
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}; |
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struct _OneWireBus |
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{ |
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bool init; |
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int gpio; |
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const struct _OneWireBus_Timing * timing; |
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bool use_crc; |
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}; |
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static void _tick_delay(int ticks) |
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{ |
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// Each tick is 0.25 microseconds.
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float time_us = ticks / 4.0; |
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ets_delay_us(time_us); |
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} |
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static bool _is_init(const OneWireBus * bus) |
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{ |
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bool ok = false; |
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if (bus != NULL) |
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{ |
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if (bus->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, "bus 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, "bus is NULL"); |
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} |
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return ok; |
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} |
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|
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/**
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* @brief Generate a 1-Wire reset. |
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* @param[in] bus Initialised bus instance. |
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* @return true if device is present, otherwise false. |
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*/ |
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static bool _reset(const OneWireBus * bus) |
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{ |
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bool present = false; |
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if (_is_init(bus)) |
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{ |
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gpio_set_direction(bus->gpio, GPIO_MODE_OUTPUT); |
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_tick_delay(bus->timing->G); |
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gpio_set_level(bus->gpio, 0); // Drive DQ low
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_tick_delay(bus->timing->H); |
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gpio_set_level(bus->gpio, 1); // Release the bus
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_tick_delay(bus->timing->I); |
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gpio_set_direction(bus->gpio, GPIO_MODE_INPUT); |
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int level1 = gpio_get_level(bus->gpio); |
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_tick_delay(bus->timing->J); // Complete the reset sequence recovery
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int level2 = gpio_get_level(bus->gpio); |
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present = (level1 == 0) && (level2 == 1); // Sample for presence pulse from slave
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ESP_LOGD(TAG, "reset: level1 0x%x, level2 0x%x, present %d", level1, level2, present); |
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} |
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return present; |
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} |
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/**
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* @brief Send a 1-Wire write bit, with recovery time. |
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* @param[in] bus Initialised bus instance. |
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* @param[in] bit The value to send. |
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*/ |
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static void _write_bit(const OneWireBus * bus, int bit) |
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{ |
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if (_is_init(bus)) |
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{ |
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int delay1 = bit ? bus->timing->A : bus->timing->C; |
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int delay2 = bit ? bus->timing->B : bus->timing->D; |
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gpio_set_direction(bus->gpio, GPIO_MODE_OUTPUT); |
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gpio_set_level(bus->gpio, 0); // Drive DQ low
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_tick_delay(delay1); |
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gpio_set_level(bus->gpio, 1); // Release the bus
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_tick_delay(delay2); |
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} |
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} |
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/**
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* @brief Read a bit from the 1-Wire bus and return the value, with recovery time. |
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* @param[in] bus Initialised bus instance. |
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*/ |
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static int _read_bit(const OneWireBus * bus) |
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{ |
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int result = 0; |
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if (_is_init(bus)) |
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{ |
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gpio_set_direction(bus->gpio, GPIO_MODE_OUTPUT); |
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gpio_set_level(bus->gpio, 0); // Drive DQ low
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_tick_delay(bus->timing->A); |
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gpio_set_level(bus->gpio, 1); // Release the bus
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_tick_delay(bus->timing->E); |
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gpio_set_direction(bus->gpio, GPIO_MODE_INPUT); |
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int level = gpio_get_level(bus->gpio); |
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_tick_delay(bus->timing->F); // Complete the timeslot and 10us recovery
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result = level & 0x01; |
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} |
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return result; |
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} |
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/**
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* @brief Write 1-Wire data byte. |
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* @param[in] bus Initialised bus instance. |
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* @param[in] data Value to write. |
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*/ |
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static void _write_byte(const OneWireBus * bus, uint8_t data) |
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{ |
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if (_is_init(bus)) |
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{ |
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ESP_LOGD(TAG, "write 0x%02x", data); |
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for (int i = 0; i < 8; ++i) |
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{ |
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_write_bit(bus, data & 0x01); |
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data >>= 1; |
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} |
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} |
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} |
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/**
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* @brief Read 1-Wire data byte from bus. |
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* @param[in] bus Initialised bus instance. |
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* @return Byte value read from bus. |
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*/ |
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static uint8_t _read_byte(const OneWireBus * bus) |
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{ |
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uint8_t result = 0; |
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if (_is_init(bus)) |
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{ |
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for (int i = 0; i < 8; ++i) |
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{ |
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result >>= 1; |
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if (_read_bit(bus)) |
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{ |
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result |= 0x80; |
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} |
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} |
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ESP_LOGD(TAG, "read 0x%02x", result); |
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} |
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return result; |
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} |
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/**
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* @param Read a block of bytes from 1-Wire bus. |
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* @param[in] bus Initialised bus instance. |
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* @param[in,out] buffer Pointer to buffer to receive read data. |
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* @param[in] len Number of bytes to read, must not exceed length of receive buffer. |
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* @return Pointer to receive buffer. |
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*/ |
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static uint8_t * _read_block(const OneWireBus * bus, uint8_t * buffer, unsigned int len) |
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{ |
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for (int i = 0; i < len; ++i) |
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{ |
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*buffer++ = _read_byte(bus); |
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} |
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return buffer; |
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} |
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/**
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* @param Write a block of bytes from 1-Wire bus. |
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* @param[in] bus Initialised bus instance. |
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* @param[in] buffer Pointer to buffer to write data from. |
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* @param[in] len Number of bytes to write. |
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* @return Pointer to write buffer. |
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*/ |
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static uint8_t * _write_block(const OneWireBus * bus, const uint8_t * buffer, unsigned int len) |
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{ |
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for (int i = 0; i < len; ++i) |
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{ |
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_write_byte(bus, buffer[i]); |
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} |
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return buffer; |
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} |
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/**
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* @brief 1-Wire 8-bit CRC lookup. |
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* @param[in] crc Starting CRC value. Pass in prior CRC to accumulate. |
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* @param[in] data Byte to feed into CRC. |
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* @return Resultant CRC value. |
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*/ |
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static uint8_t _calc_crc(uint8_t crc, uint8_t data) |
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{ |
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// https://www.maximintegrated.com/en/app-notes/index.mvp/id/27
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static const uint8_t table[256] = { |
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0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65, |
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157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220, |
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35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98, |
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190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255, |
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70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7, |
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219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154, |
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101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36, |
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248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185, |
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140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205, |
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17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80, |
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175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238, |
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50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115, |
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202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139, |
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87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22, |
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233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168, |
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116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53 |
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}; |
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return table[crc ^ data]; |
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} |
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// Public API
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OneWireBus * owb_malloc() |
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{ |
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OneWireBus * bus = malloc(sizeof(*bus)); |
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if (bus != NULL) |
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{ |
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memset(bus, 0, sizeof(*bus)); |
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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 bus; |
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} |
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void owb_free(OneWireBus ** bus) |
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{ |
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if (bus != NULL && (*bus != NULL)) |
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{ |
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free(bus); |
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*bus = NULL; |
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} |
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} |
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void owb_init(OneWireBus * bus, int gpio) |
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{ |
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if (bus != NULL) |
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{ |
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bus->gpio = gpio; |
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bus->timing = &_StandardTiming; |
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bus->init = true; |
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// platform specific:
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gpio_pad_select_gpio(bus->gpio); |
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} |
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else |
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{ |
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ESP_LOGE(TAG, "bus is NULL"); |
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} |
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} |
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void owb_use_crc(OneWireBus * bus, bool use_crc) |
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{ |
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if (_is_init(bus)) |
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{ |
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bus->use_crc = use_crc; |
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ESP_LOGD(TAG, "use_crc %d", bus->use_crc); |
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} |
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} |
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int owb_rom_search(OneWireBus * bus) |
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{ |
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// TODO
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return 0; |
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} |
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uint64_t owb_read_rom(const OneWireBus * bus) |
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{ |
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uint64_t rom_code = 0; |
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if (_is_init(bus)) |
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{ |
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if (_reset(bus)) |
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{ |
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uint8_t buffer[8] = { 0 }; |
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_write_byte(bus, OWB_ROM_READ); |
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_read_block(bus, buffer, 8); |
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// device provides LSB first
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for (int i = 7; i >= 0; --i) |
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{ |
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// watch out for integer promotion
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rom_code |= ((uint64_t)buffer[i] << (8 * i)); |
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} |
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if (bus->use_crc) |
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{ |
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// check CRC
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uint8_t crc = 0; |
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for (int i = 0; i < 8; ++i) |
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{ |
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crc = _calc_crc(crc, buffer[i]); |
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} |
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ESP_LOGD(TAG, "crc 0x%02x", crc); |
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if (crc != 0) |
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{ |
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ESP_LOGE(TAG, "CRC failed"); |
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rom_code = 0; |
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} |
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ESP_LOGD(TAG, "rom_code 0x%08" PRIx64, 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 rom_code; |
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} |
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bool owb_reset(const OneWireBus * bus) |
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{ |
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return _reset(bus); |
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} |
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void owb_write_byte(const OneWireBus * bus, uint8_t data) |
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{ |
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_write_byte(bus, data); |
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} |
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uint8_t owb_read_byte(const OneWireBus * bus) |
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{ |
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return _read_byte(bus); |
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} |
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uint8_t * owb_read_bytes(const OneWireBus * bus, uint8_t * buffer, unsigned int len) |
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{ |
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return _read_block(bus, buffer, len); |
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} |
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uint8_t * owb_write_bytes(const OneWireBus * bus, const uint8_t * buffer, unsigned int len) |
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{ |
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return _write_block(bus, buffer, len); |
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} |
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void owb_write_rom_code(const OneWireBus * bus, uint64_t rom_code) |
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{ |
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uint8_t buffer[sizeof(uint64_t)] = {0}; |
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for (int i = 0; i < sizeof(buffer); ++i) |
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{ |
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// LSB first
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buffer[i] = rom_code & 0xFF; |
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rom_code >>= 8; |
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} |
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_write_block(bus, buffer, sizeof(buffer)); |
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} |
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uint8_t owb_crc8(uint8_t crc, uint8_t data) |
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{ |
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return _calc_crc(crc, data); |
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} |
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@ -0,0 +1,116 @@ |
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#ifndef ONE_WIRE_BUS_H |
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#define ONE_WIRE_BUS_H |
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#include <stdint.h> |
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#ifdef __cplusplus |
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extern "C" { |
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#endif |
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// ROM commands
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#define OWB_ROM_SEARCH 0xF0 |
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#define OWB_ROM_READ 0x33 |
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#define OWB_ROM_MATCH 0x55 |
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#define OWB_ROM_SKIP 0xCC |
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#define OWB_ROM_SEARCH_ALARM 0xEC |
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typedef struct _OneWireBus OneWireBus; |
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typedef uint64_t OneWireBusROMCode; |
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/**
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* @brief Construct a new 1-Wire bus instance. |
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* New instance should be initialised before calling other functions. |
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* @return Pointer to new bus instance, or NULL if it cannot be created. |
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*/ |
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OneWireBus * owb_malloc(void); |
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/**
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* @brief Delete an existing device info instance. |
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* @param[in] bus Pointer to bus instance. |
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* @param[in,out] ds18b20_info Pointer to device info instance that will be freed and set to NULL. |
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*/ |
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void owb_free(OneWireBus ** bus); |
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/**
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* @brief Initialise a 1-Wire bus instance with the specified GPIO. |
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* @param[in] bus Pointer to bus instance. |
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* @param[in] gpio GPIO number to associate with device. |
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*/ |
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void owb_init(OneWireBus * bus, int gpio); |
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/**
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* @brief Enable or disable use of CRC checks on device communications. |
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* @param[in] bus Pointer to initialised bus instance. |
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* @param[in] use_crc True to enable CRC checks, false to disable. |
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*/ |
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void owb_use_crc(OneWireBus * bus, bool use_crc); |
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/**
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* @brief Read 64-bit ROM code from device - only works when there is a single device on the bus. |
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* @param[in] bus Pointer to initialised bus instance. |
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* @return The 64-bit value read from the device's ROM. |
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*/ |
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uint64_t owb_read_rom(const OneWireBus * bus); |
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/**
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* @brief Reset the 1-Wire bus. |
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* @param[in] bus Pointer to initialised bus instance. |
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* @return True if at least one device is present on the bus. |
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*/ |
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bool owb_reset(const OneWireBus * bus); |
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/**
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* @brief Write a single byte to the 1-Wire bus. |
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* @param[in] bus Pointer to initialised bus instance. |
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* @param[in] data Byte value to write to bus. |
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*/ |
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void owb_write_byte(const OneWireBus * bus, uint8_t data); |
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/**
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* @brief Read a single byte from the 1-Wire bus. |
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* @param[in] bus Pointer to initialised bus instance. |
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* @return The byte value read from the bus. |
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*/ |
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uint8_t owb_read_byte(const OneWireBus * bus); |
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/**
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* @brief Read a number of bytes from the 1-Wire bus. |
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* @param[in] bus Pointer to initialised bus instance. |
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* @param[in, out] buffer Pointer to buffer to receive read data. |
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* @param[in] len Number of bytes to read, must not exceed length of receive buffer. |
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* @return Pointer to receive buffer. |
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*/ |
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uint8_t * owb_read_bytes(const OneWireBus * bus, uint8_t * buffer, unsigned int len); |
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/**
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* @brief Write a number of bytes to the 1-Wire bus. |
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* @param[in] bus Pointer to initialised bus instance. |
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* @param[in] buffer Pointer to buffer to write data from. |
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* @param[in] len Number of bytes to write. |
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* @return Pointer to write buffer. |
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*/ |
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uint8_t * owb_write_bytes(const OneWireBus * bus, const uint8_t * buffer, unsigned int len); |
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/**
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* @brief Write a ROM code to the 1-Wire bus ensuring LSB is sent first. |
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* @param[in] bus Pointer to initialised bus instance. |
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* @param[in] rom_code ROM code to write to bus. |
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*/ |
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void owb_write_rom_code(const OneWireBus * bus, uint64_t rom_code); |
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/**
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* @brief 1-Wire 8-bit CRC lookup. |
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* @param[in] crc Starting CRC value. Pass in prior CRC to accumulate. |
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* @param[in] data Byte to feed into CRC. |
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* @return Resultant CRC value. |
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*/ |
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uint8_t owb_crc8(uint8_t crc, uint8_t data); |
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#ifdef __cplusplus |
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} |
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#endif |
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#endif // DS18B20_H
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