174 lines
5.2 KiB
Markdown
174 lines
5.2 KiB
Markdown
# DHT11 Temperature & Humidity Sensor for ESP32-C3
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ESP-IDF project that reads temperature and humidity data from a DHT11 sensor and prints it to the serial console.
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## Overview
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This project reads data from a **DHT11** digital temperature and humidity sensor using the ESP32-C3 microcontroller. It implements the DHT11 communication protocol in software, reads sensor values every 5 seconds, validates the checksum, and displays:
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- Current date and time (derived from compile time)
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- Chip information (model, cores, features, flash size, silicon revision)
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- Humidity percentage with 1 decimal place
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- Temperature in Celsius with 1 decimal place
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- Checksum validation status
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## Hardware Requirements
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| Component | Details |
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|-----------|---------|
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| Microcontroller | ESP32-C3 |
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| Sensor | DHT11 (AM2302) |
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| Connection | Single wire + pull-up resistor |
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| Data Pin | **GPIO 0** (configurable in `main/main.c`) |
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| Resistor | 4.7kΩ - 10kΩ pull-up between VCC and DATA |
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- [Datasheet ESP32-C3 Super Mini](https://www.espboards.dev/esp32/esp32-c3-super-mini/s)
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- [Datasheet DHT11 Supplier](https://asairsensors.com/product/dht11-sensor/)
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- [Datasheet DHT11 Protocol](https://www.mouser.com/datasheet/2/758/DHT11-Technical-Data-Sheet-Translated-Version-1143054.pdf?srsltid=AfmBOoqtetK1e7kNT-24HGdKDaQMV55sFB9Yr4rK94icO4YI94qwFuFz)
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- [ESP IDF get started](https://docs.espressif.com/projects/esp-idf/en/v6.0/esp32c3/get-started/linux-macos-start-project.html)
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### Wiring Diagram
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```
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DHT11 ESP32-C3
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VCC ------ 3V3
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DATA ----- GPIO0
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GND ------ GND
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```
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Add a **4.7kΩ pull-up resistor** between VCC and DATA pin.
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## Supported Targets
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| ESP32 | ESP32-C2 | ESP32-C3 | ESP32-S2 | ESP32-S3 |
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| ----- | -------- | -------- | -------- | -------- |
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| ❌ | ❌ | ✅ | ❌ | ❌ |
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## Project Structure
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```
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dht11_reader/
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├── CMakeLists.txt # Project configuration
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├── sdkconfig # Build configuration
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├── main/
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│ ├── CMakeLists.txt # Main component configuration
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│ └── main.c # Application source code
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└── README.md # This file
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```
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## Setup & Build
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### Prerequisites
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- [ESP-IDF v6.0](https://docs.espressif.com/projects/esp-idf/en/v6.0/esp32c3/get-started/index.html)
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- RISC-V toolchain (riscv32-esp-elf)
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- Python 3.13+ with virtual environment
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### Build Instructions
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```bash
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# Activate ESP-IDF environment
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source "$HOME/.espressif/tools/activate_idf_v6.0.sh"
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# Navigate to project
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cd temperature_measure
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# Build the project
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idf.py build
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# Flash to device (replace PORT with your serial port)
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idf.py -p /dev/ttyUSB0 flash monitor
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```
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## Configuration
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The DHT11 data pin is defined in `main/main.c`:
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```c
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#define DHT11_GPIO 0
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```
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To use a different GPIO, change this define and rebuild.
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### Reading Interval
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The sensor is read every 5 seconds:
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```c
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vTaskDelay(pdMS_TO_TICKS(5000));
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```
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Note: DHT11 requires at least 1 second between readings. Adjust as needed.
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## How It Works
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### DHT11 Communication Protocol
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1. **Start Signal**: MCU pulls DATA line low for 20ms, then high
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2. **Sensor Response**: DHT11 pulls line low for ~80μs, then high for ~80μs
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3. **Data Transmission**: 40 bits of data (5 bytes) in the following format:
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- Byte 0: Humidity integer part
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- Byte 1: Humidity decimal part
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- Byte 2: Temperature integer part
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- Byte 3: Temperature decimal part
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- Byte 4: Checksum (sum of bytes 0-3)
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4. **Bit Encoding**: Each bit starts with a ~50μs low pulse:
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- `0`: ~26-28μs high pulse
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- `1`: ~70μs high pulse
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### Checksum Validation
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The checksum byte should equal the sum of the first 4 data bytes. If validation fails, the reading is retried after 1 second.
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## Output Example
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```
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Time: 2024-04-24 22:30:00
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This is esp32c3 chip with 1 CPU core(s), WiFi/BLE, silicon revision v0.4, 4MB embedded flash
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Minimum free heap size: 283488 bytes
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Humidity: 45.2%
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Temperature: 23.5°C
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Checksum valid: Yes
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```
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## Troubleshooting
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### Common Issues
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| Issue | Solution |
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|-------|----------|
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| No sensor readings / checksum fails | Check wiring: DATA to GPIO0, pull-up resistor present |
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| Build fails with missing component | Run `idf.py fullclean` then rebuild |
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| `driver/gpio.h` not found | Ensure `esp_driver_gpio` is in PRIV_REQUIRES |
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| Linker errors with `.riscv.attributes` | Your toolchain may be too new; use ESP-IDF 6.0 compatible version |
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### Debug Mode
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To enable debug output:
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```bash
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idf.py monitor
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```
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### Hardware Connection Check
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Verify your wiring with a multimeter:
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- GPIO0 should read HIGH when idle (via pull-up)
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- 3V3 is supplying power
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- GND is properly connected
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## Technical Details
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- **Sensor Range**: 0-50°C temperature, 20-90% humidity
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- **Accuracy**: ±1°C temperature, ±1% humidity
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- **Sampling Rate**: 1Hz maximum (1 reading per second)
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- **Resolution**: 1° C, 1% humidity
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## License
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This project is provided under the **CC0-1.0** license (public domain). See the SPDX identifier in the source file.
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## Resources
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- [DHT11 Datasheet](https://www.mouser.com/datasheet/2/718/DHT11-Technical-Data-Sheet-Translated-Version-1137654.pdf)
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- [ESP32-C3 Documentation](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c3/)
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- [ESP-IDF Programming Guide](https://docs.espressif.com/projects/esp-idf/en/latest/esp32c3/api-guides/index.html)
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