Frédéric Blanc » ESP32

h1. Wiki

h2. Overview 

ESP32 is a series of low-cost, low-power system on a chip microcontrollers with integrated Wi-Fi (802.11 b/g/n) and dual-mode Bluetooth(v4.2 BR/EDR and BLE). The ESP32 series employs a Tensilica Xtensa LX6 microprocessor in both dual-core and single-core variations and includes in-built antenna switches, RF balun, power amplifier, low-noise receive amplifier, filters, and power-management modules. ESP32 is created and developed by Espressif Systems, a Shanghai-based Chinese company, and is manufactured by TSMC using their 40 nm process. It is a successor to the ESP8266 microcontroller. 

https://www.espressif.com/en/products/hardware/esp32/overview

h2. Hardware

h3. Core

*CPU*: Xtensa dual-core (or single-core) 32-bit LX6 microprocessor, operating at 160 or 240 MHz and performing at up to 600 DMIPS

*Memory*: 520KiB SRAM

*Power* management: 5uA deep sleep current

h3. Wi-Fi

Wi-Fi: 802.11 b/g/n

h3. Bluetooth

Bluetooth v4.2 BR/EDR and BLE

h3. ADC

!{width: 50%}esp32_adc001.png!

Features

• Two SAR ADCs, with simultaneous sampling and conversion

• Up to five SAR ADC controllers for different purposes (e.g. high performance, low power or PWDET /PKDET).

• Up to 18 analog input pads

• One channel for internal voltage vdd33, two for pa_pkdet (available on selected controllers)

• Low-noise amplifier for small analog signals (available on one controller)

• 12-bit, 11-bit, 10-bit, 9-bit configurable resolution

• DMA support (available on one controller)

• Multiple channel-scanning modes (available on two controllers)

• Operation during deep sleep (available on one controller)

• Controlled by a ULP coprocessor (available on two controllers)

h2. Software

h3. Filesystem

*File system object (SPIFFS)*

The filesystem implementation for ESP8266 had to accomodate the constraints of the chip, among which its limited RAM. SPIFFS was selected because it is designed for small systems, but that comes at the cost of some simplifications and limitations.

https://arduino-esp8266.readthedocs.io/en/2.4.2/filesystem.html

h3. OTA Updates

OTA (Over the Air) update is the process of loading the firmware to ESP module using Wi-Fi connection rather than a serial port. Such functionality became extremely useful in case of limited or no physical access to the module.

https://arduino-esp8266.readthedocs.io/en/2.4.2/ota_updates/readme.html

h2. Example

WebSockets for awesome on the ESP8266

https://www.youtube.com/watch?v=8ISbmQTbjDI

https://github.com/cnlohr/colorchord