<p>The ESP32-Node is designed to be a low-cost, vanila solution for experimenting with embedded and IoT devices. The ESP32-Node is intended to College students taking Electronics program or advanced users who are looking for functional ESP32 embedded board with minimal size.</p>
<p>The adapter allows interchangability of ESP32 modules between different nodes. The adapter contains minimal components on its PCB, just enough to ensure module's operation. (ESP32 8-N-1)</p>
The LM75A is an industry-standard digital temperature sensor. The LM75A provides 9-bit digital temperature readings with an accuracy of ±2°C from –25°C to 100°C
and ±3°C over –55°C to 125°C. The LM75A operates with a single supply from +2.7 V to +5.5 V. Communication is accomplished over a 2-wire interface which operates up to 400kHz.
The LM75A has three address pins, allowing up to eight LM75A devices to operate on the same 2-wire bus. The LM75A has a dedicated over-temperature output (O.S.) with
programmable limit and hysteresis. This output has programmable fault tolerance, which allows the user to
define the number of consecutive error conditions that must occur before O.S. is activated.
BME280 is combined temperature, humidity and pressure sensor. The unit combines high linearity and high accuracy sensors and is perfectly feasible for low current consumption, long-term stability and high EMC robustness. The humidity sensor offers an extremely fast response time and therefore supports performance requirements for emerging applications such as context awareness, and high accuracy over a wide temperature range.[^2]
Below is the functional diagram of BME-/BMP-280. Notable difference between the two devices, is that BME-280 is capable of measuring relative humidity. BME-280 has square shape, while BMP-280 has rectangular shape.
> BM**E**280[^2] and BM**P**280[^3] look almost identical. However, BME280 sensor has a square form, while BMP280 has a rectangular form. In addition, the two sensor boards can have different I<sup>2</sup>C addresses.
The BME280 sensor board interface uses 4 pins and is 13mm by 10.5mm in size. The four pins are `VIN`, `GND`, `SCL` and `SDA`. The measured values are sent via I<sup>2</sup>C protocol. The I<sup>2</sup>C slave address is pre-defined and can take value either 0x76 or 0x77 (BME280 Datasheet, page 32)[^4].
<p>Data readout is done by starting a burst read from 0xF7 to 0xFC (temperature and pressure) or from 0xF7 to 0xFE (temperature, pressure, and humidity). The data are rad out in an unsigned 20-bit format both for pressure and for temperature, and in an unsigned 26-bit format for humidity. After the uncompensated values for pressure, temperature, and humidity have been read, the actual humidity, pressure and temperature needs to be calculated using the compensation parameters stored in the device.</p>