/* * Copyright (c) 2022 Thomas Stranger * * SPDX-License-Identifier: Apache-2.0 */ /** * Driver for DS18B20 1-Wire temperature sensors * A datasheet is available at: * https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf * * Parasite power configuration is not supported by the driver. */ #define DT_DRV_COMPAT maxim_ds18b20 #include #include #include #include #include "ds18b20.h" LOG_MODULE_REGISTER(DS18B20, CONFIG_SENSOR_LOG_LEVEL); static int ds18b20_configure(const struct device *dev); /* measure wait time for 9-bit, 10-bit, 11-bit, 12-bit resolution respectively */ static const uint16_t measure_wait_ms[4] = { 94, 188, 376, 750 }; static inline void ds18b20_temperature_from_raw(uint8_t *temp_raw, struct sensor_value *val) { int16_t temp = sys_get_le16(temp_raw); val->val1 = temp / 16; val->val2 = (temp % 16) * 1000000 / 16; } /* * Write scratch pad, read back, then copy to eeprom */ static int ds18b20_write_scratchpad(const struct device *dev, struct ds18b20_scratchpad scratchpad) { struct ds18b20_data *data = dev->data; const struct device *bus = ds18b20_bus(dev); uint8_t sp_data[4] = { DS18B20_CMD_WRITE_SCRATCHPAD, scratchpad.alarm_temp_high, scratchpad.alarm_temp_low, scratchpad.config }; return w1_write_read(bus, &data->config, sp_data, sizeof(sp_data), NULL, 0); } static int ds18b20_read_scratchpad(const struct device *dev, struct ds18b20_scratchpad *scratchpad) { struct ds18b20_data *data = dev->data; const struct device *bus = ds18b20_bus(dev); uint8_t cmd = DS18B20_CMD_READ_SCRATCHPAD; return w1_write_read(bus, &data->config, &cmd, 1, (uint8_t *)&scratchpad[0], 9); } /* Starts sensor temperature conversion without waiting for completion. */ static int ds18b20_temperature_convert(const struct device *dev) { int ret; struct ds18b20_data *data = dev->data; const struct device *bus = ds18b20_bus(dev); (void)w1_lock_bus(bus); ret = w1_reset_select(bus, &data->config); if (ret != 0) { goto out; } ret = w1_write_byte(bus, DS18B20_CMD_CONVERT_T); out: (void)w1_unlock_bus(bus); return ret; } /* * Write resolution into configuration struct, * but don't write it to the sensor yet. */ static void ds18b20_set_resolution(const struct device *dev, uint8_t resolution) { struct ds18b20_data *data = dev->data; data->scratchpad.config &= ~DS18B20_RESOLUTION_MASK; data->scratchpad.config |= DS18B20_RESOLUTION(resolution); } static int ds18b20_sample_fetch(const struct device *dev, enum sensor_channel chan) { const struct ds18b20_config *cfg = dev->config; struct ds18b20_data *data = dev->data; int status; __ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL || chan == SENSOR_CHAN_AMBIENT_TEMP); if (!data->lazy_loaded) { status = ds18b20_configure(dev); if (status < 0) { return status; } data->lazy_loaded = true; } status = ds18b20_temperature_convert(dev); if (status < 0) { LOG_DBG("W1 fetch error"); return status; } k_msleep(measure_wait_ms[DS18B20_RESOLUTION_INDEX(cfg->resolution)]); return ds18b20_read_scratchpad(dev, &data->scratchpad); } static int ds18b20_channel_get(const struct device *dev, enum sensor_channel chan, struct sensor_value *val) { struct ds18b20_data *data = dev->data; if (chan != SENSOR_CHAN_AMBIENT_TEMP) { return -ENOTSUP; } ds18b20_temperature_from_raw((uint8_t *)&data->scratchpad.temp, val); return 0; } static int ds18b20_configure(const struct device *dev) { const struct ds18b20_config *cfg = dev->config; struct ds18b20_data *data = dev->data; int ret; if (w1_reset_bus(cfg->bus) <= 0) { LOG_ERR("No 1-Wire slaves connected"); return -ENODEV; } /* In single drop configurations the rom can be read from device */ if (w1_get_slave_count(cfg->bus) == 1) { if (w1_rom_to_uint64(&data->config.rom) == 0ULL) { (void)w1_read_rom(cfg->bus, &data->config.rom); } } else if (w1_rom_to_uint64(&data->config.rom) == 0ULL) { LOG_DBG("nr: %d", w1_get_slave_count(cfg->bus)); LOG_ERR("ROM required, because multiple slaves are on the bus"); return -EINVAL; } if ((cfg->family != 0) && (cfg->family != data->config.rom.family)) { LOG_ERR("Found 1-Wire slave is not a DS18B20"); return -EINVAL; } /* write default configuration */ ds18b20_set_resolution(dev, cfg->resolution); ret = ds18b20_write_scratchpad(dev, data->scratchpad); if (ret < 0) { return ret; } LOG_DBG("Init DS18B20: ROM=%016llx\n", w1_rom_to_uint64(&data->config.rom)); return 0; } int ds18b20_attr_set(const struct device *dev, enum sensor_channel chan, enum sensor_attribute attr, const struct sensor_value *thr) { struct ds18b20_data *data = dev->data; if ((enum sensor_attribute_w1)attr != SENSOR_ATTR_W1_ROM) { return -ENOTSUP; } data->lazy_loaded = false; w1_sensor_value_to_rom(thr, &data->config.rom); return 0; } static const struct sensor_driver_api ds18b20_driver_api = { .attr_set = ds18b20_attr_set, .sample_fetch = ds18b20_sample_fetch, .channel_get = ds18b20_channel_get, }; static int ds18b20_init(const struct device *dev) { const struct ds18b20_config *cfg = dev->config; struct ds18b20_data *data = dev->data; if (device_is_ready(cfg->bus) == 0) { LOG_DBG("w1 bus is not ready"); return -ENODEV; } w1_uint64_to_rom(0ULL, &data->config.rom); data->lazy_loaded = false; /* in multidrop configurations the rom is need, but is not set during * driver initialization, therefore do lazy initialization in all cases. */ return 0; } #define DS18B20_CONFIG_INIT(inst) \ { \ .bus = DEVICE_DT_GET(DT_INST_BUS(inst)), \ .family = (uint8_t)DT_INST_PROP_OR(inst, family_code, 0x28), \ .resolution = DT_INST_PROP(inst, resolution), \ } #define DS18B20_DEFINE(inst) \ static struct ds18b20_data ds18b20_data_##inst; \ static const struct ds18b20_config ds18b20_config_##inst = \ DS18B20_CONFIG_INIT(inst); \ SENSOR_DEVICE_DT_INST_DEFINE(inst, \ ds18b20_init, \ NULL, \ &ds18b20_data_##inst, \ &ds18b20_config_##inst, \ POST_KERNEL, \ CONFIG_SENSOR_INIT_PRIORITY, \ &ds18b20_driver_api); DT_INST_FOREACH_STATUS_OKAY(DS18B20_DEFINE)