ESP-Nodes

Eco-system of ESP32s Nodes and ATtiny85 peripherals with different functionalities.

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.

ESP32-Node Features:

• Uses bare-bones ESP32-WROOM-32D Module ¹
• Direct connections to all GPIOs
• Miniature in size; only 35.7mm x 35.7mm
• Built-in 3V3 voltage regulator (V_max=15V) and reversed supply voltage polarity protection
• Pre-wired strapping pins for ensuring proper booting on power-on
• blue power-on LED
• two programmable LEDs
• programmable via UART -> no need for serial drivers

ESP32-WROOM-32D Module Adapter Pinouts

ESP32-WROOM-32D modules are well suited for Wi-Fi and Bluetooth/Bluetooth LE-based connectivity applications and provide a solid dual-core performance. These modules target a wide variety of applications, ranging from low-power sensor networks to the most demanding tasks, such as voice encoding, music streaming and MP3 decoding.

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)

ESP32-WROOM Schematic Checklist

Physical Pin	Descrption and Logical Pin	Extended Function
1 15 38	Ground
2	3V3
3	EN
4 5 6 7	Inputs Only GPIO36 GPIO39 GPIO34 GPIO35	ADC1_CH0, ADC1_CH3, ADC1_CH6, ADC1_CH7
8 9	GPIO32 GPIO33	TOUCH_9, TOUCH_8
10 11	GPIO25 GPIO26	DAC_1, DAC_2
12	GPIO27	TOUCH_7
13 14	GPIO14 GPIO12	HSPI_CLK HSPI_MISO TOUCH_6 TOUCH_7
16	GPIO13	HSPI_MOSI ADC2_CH4
17 18 19 20 21 22	Module Internal Use Only GPIO09 GPIO10 GPIO11 GPIO08 GPIO07 GPIO06
23 24	GPIO02 GPIO15	AD2_CH3 ADC2_CH2
25 26	GPIO00 GPIO04	TOUCH_1 TOUCH_0
27 28	GPIO16 GPIO17	UART2_RXD UART2_TXD
29 30 31	GPIO05 GPIO18 GPIO19	VSPI_CS0 VSPI_CLK VSPI_MISO
32	Not Connected
33	GPIO21	SDA
34 35	GPIO03 GPIO01	UART0_RXD UART0_TXD
36	GPIO22	SCL
37	GPIO23	VSPI_MOSI

ESP32-C3 Module Adapter Pinouts

ESP32-C3 is a cost-effective, RISC-V-based MCU with Wi-Fi and Bluetooth 5 (LE) connectivity for secure IoT applications. ESP32-C3 Module offfers a cost-effective RISC-V MCU with Wi-Fi and Bluetooth 5 (LE) connectivity for secure IoT applications. ²

These modules have a rich set of peripherals and high performance make the two modules an ideal choice for smart homes, industrial automation, health care, consumer electronics, etc

ESP32-C3 has 32-bit RISC-V-based MCU single-core processor with 400KB of SRAM, which is capable of running at 160MHz. t has integrated 2.4 GHz Wi-Fi and Bluetooth 5 (LE) with a long-range support. It has 22 programmable GPIOs with support for ADC, SPI, UART, I2C, I2S, RMT, TWAI, and PWM.

ESP32-C3 Schematics Checklist

Strapping & Control Pins

Pin	Default	Description
EN	-	H: enables chip L: disables chip
GPIO2	n/a	1 -> Download boot
GPIO8	n/a	1 -> Download boot

DC Characteristics

Variable	Parameter	min	Typ	max	Unit
VIH	High-level Input voltage	0.75xVDD	-	VDD + 0.3	V
IIH	High-level Input current	-	-	50	nA
VIL/sub>	Low-level Input voltage	-0.3	-	0.25xVDD	V
IIL	Low-level Input current	-	-	50	nA
VOH	High-level Output voltage	0.8xVDD	-	-	V
IOH	High-level Source current	-	40	-	mA
VOL/sub>	Low-level Output voltage	-	-	0.1xVDD	V
IOL	Low-level Sinc current	-	28	-	mA
RPU	Pull-up resistor	-	45	-	kOm
RPD	Pull-down resistor	-	45	-	kOm
VIH_nRST	Chip reset release voltage	0.75xVDD	-	VDD + 0.3	V
VIL_nRST	Chip reset voltage	0.75xVDD	-0.3	0.25xVDD	V

Programming via UART

ESP32 modules can be programmed using USB-UART adapter connected to the corresponding UART pins on the ESP32 module. This approach allows to save space on PCB boards, which is very helpful when PCB dimentions have constraints.

Important

Remember to swap Tx and Rx between receiver and sender (i.e. Rx on a sender side becomes Tx on a receiver side).

Connect Tx and Rx to their sorresponding pins: GPIOs GPIO03 and GPIO01 on ESP32-Module; or pins 34 and 35 on ESP32 adapter board.

Unified Configuration Framework

ESP Nodes performing specific operations can use different ESP32 Modules for optimization purposes. As dicersity of ESP32s being used by the Nodes increases, so does the code. However, in order to keep core code independent from the ESP32 Module being used, the so-called configurations specific for the particular ESP32 Module are defined in config.h file.

Important

Remember to add entry for congif.h inside .gitignore file to prevent Git from pushing security sensitive data to the repository.

const *char WIFI_SSID = "IoT_bots";
const *char WIFI_PASSWORD = "405405405";

/* ESP32-WROOM Module */
#ifdef ESP32-WROOM
#define SCL_PIN         (22)
#define SDA_PIN         (21)
#endif

/* ESP32-C3 Module */

/* ESP32-S3 Module */

/* ESP32-C3 Super Mini */
#ifdef ESP32-C3-SuperMini
#define SCL_PIN         (7)
#define SDA_PIN         (6)
#define SYS_LED_PIN     (8)
#define SCK_PIN         (8)
#define MISO_PIN        (9)
#define MOSI_PIN        (10)
#define UART_RX_PIN     (20)
#define UART_TX_PIN     (21)
#define ADC1_PIN        (1)
#define ADC2_PIN        (0)
#define A0_PIN          (2)
#define A1_PIN          (3)
#define A2_PIN          (4)
#define A3_PIN          (5)
#endif

/* BME-280 */
#ifdef BME280
#define I2C_ADDRESS_BME280  0x76
#endif
/* BMP-280 */
#ifdef BME280
#define I2C_ADDRESS_BMP280  0x76
#endif

Bare-bones ESP32 module can be programmed via UART interface (GPIO03 and GPIO01) using USB to UART adapter.

Temperature Node. The Key Elements and Components

The Temperature Node broadcasts the air temperature, atmospheric pressure and air humidity over secured MQTT.

I2C Air Temperature Thermostat (LM75A)

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.

address: 0x49

I2C Air Temperature, Pressure and Humidity Sensor Board (BME280)

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.³

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.

BME-280 can come in a ready-to-use PCB ...

Important

BME280³ and BMP280⁴ 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 I²C addresses.

4-pin variant

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 I²C protocol. The I²C slave address is pre-defined and can take value either 0x76 or 0x77 (BME280 Datasheet, page 32)⁵.

Wiring

Pin	ESP32 GPIO
SCL	GPIO22
SDA	GPIO21

Reading Values

i2c_master_write_read_device(I2C_MASTER_NUM, 0x76, &reg_addr, 1, data, len, I2C_MASTER_TIMEOUT_MS / portTICK_PERIOD_MS);

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.

BME-/BMP-280 can communicate via I²C. The two diagrams below summarize algorithm of reading and writting values to/from the sensor.

Display Node

OLED address = 0x3C
0.91" 128x32

e-Paper

ESP32-WROOM Module

Wiring table

ESP32-WROOM	e-Paper
GPIO4 (hSPI HD)	BUSY (Purple)
GPIO5 (vSPI CS)	CS (Orange)
GPIO16 (RxD)	RST (White)
GPIO17 (TxD)	DC (Green)
GPIO18 (vSPI CLK)	CLK (Yellow)
GPIO23 (vSPI D)	DIN (Blue)

ESP32-C3

ESP32-C3	e-Paper
GPIO7 (fSPI D)	DIN (Blue)
GPIO10 (fSPI CS)	CS (Orange)
RXD GPIO20 (RxD)	RST (White)
TXD GPIO21 (TxD)	DC (Green)
GPIO6 (fSPI CLK)	CLK (Yellow)
GPIO4 (fSPI HD)	BUSY (Purple)

Espressif ESP RainMaker and Matter Provisioning

ESP RainMaker is a complete, yet light-weight, AIoT solution that enables private Cloud deployment for your business in a simple, cost-effective and efficient manner. ESP RainMaker is a light-weight AIoT Cloud software, fully integrated into the AWS serverless architecture, which allows customers to build, develop and deploy customized AIoT solutions with a minimum amount of code and maximum security. ⁶

Espressif offers a complete solution that includes private deployment of IoT cloud, mobile apps, voice assistant skills, and product solution support. This allows customers to build their very own brand of an IoT business in as efficient, affordable and speedy as possible a way.

Matter ^{7 8} is an industry-unifying standard that provides reliable and secure connectivity for smart-home devices. It is an IP-based connectivity protocol that works on Wi-Fi, Ethernet, and Thread (over 802.15.4 radio) transports with Bluetooth LE being used for commissioning. The Matter standard is defined by the Connectivity Standards Alliance in association with all the industry leaders.

ESP Rainmaker Tutorial

Standard set of IoTs types include: ^{9 10}

• Lightbulb
• Switch
• Light
• Fan
• Temperature Sensor
• Outlet
• Plug
• Socket
• Lock
• Internal Blinds
• External Blinds
• Garage Door
• Speaker
• Air Conditioner
• Thermostat
• TV
• Washer
• Contact Sensor
• Motion Sensor
• Door Bell
• Security Panel
• Water Heater
• Other

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REFERENCES

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1. https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf ↩︎

2. https://www.espressif.com/en/news/ESP32_C3 ↩︎

3. https://www.bosch-sensortec.com/products/environmental-sensors/humidity-sensors-bme280/ ↩︎

4. https://www.bosch-sensortec.com/products/environmental-sensors/pressure-sensors/bmp280/ ↩︎

5. https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bme280-ds002.pdf ↩︎

6. https://rainmaker.espressif.com/ ↩︎

7. https://www.espressif.com/en/solutions/device-connectivity/esp-matter-solution ↩︎

8. https://github.com/project-chip/connectedhomeip ↩︎

9. https://rainmaker.espressif.com/docs/get-started/ ↩︎

10. https://rainmaker.espressif.com/docs/standard-types ↩︎