Espressif ESP-32 System On Chip

A complete, WiFi enabled, 3.3v microcontroller for less than $5^

Also: ESP-8266

Features:

• Single (ESP32-S) or Dual-core (ESP32-D) Tensilica LX6 microprocessor
• Up to 240MHz clock frequency
• Memory
  • 520kB internal SRAM
  • 8 KB "FAST" SRAM in RTC for main CPU RTC Boot from Deep-sleep
  • 8 KB "SLOW" SRAM in RTC for co-processor during Deep-sleep
  • 448 KB Boot/core ROM
  • 1 Kbit eFuse, 768 bytes for customer use
  • External FLASH up to 16 MB
  • External SRAM up to 8 MB
  • Internal FLASH (varies per model) ESP32-D2WD has a 16-Mbit, 40-MHz embedded flash, connected via pins GPIO16, GPIO17, SD_CMD, SD_CLK, SD_DATA_0 and SD_DATA_1.
• Power:
  • 2.2 to 3.6V operating range
  • 5 uA Hibernation with RTC current
  • 10 uA Deep sleep with RTC clock and memory
  • 100uA - 150uA Deep sleep with ULP co-processor running
  • 20 - 50mA Radios off: Dual CPU at 240 MHz 30 mA ~ 68 mA, 160 MHz Dual CPU 27 mA ~ 44 mA, Single-core 27 mA ~ 34 mA, 80 MHz Dual-core 20 mA ~ 31 mA, Single-core 20 mA ~ 25 mA
  • 95 - 130mA with BLE on and WiFi off
  • 95 - 240mA with WiFi on
• Integrated 802.11 BGN WiFi transceiver
• Integrated dual-mode Bluetooth (classic and BLE)
• Hardware accelerated encryption (AES, SHA2, ECC, RSA-4096)
• 32 GPIO with pin mapping
• 10-electrode capacitive touch support
• 18 ADC channels. Dual 12 bit SAR. Avoid: ADC2 (used by WiFi and some boot functions)
• 3 SPI interfaces
• 3 UART interfaces
• Two I2C interfaces
• 16 PWM outputs (Use LEDC(pin, value); in Arduino IDE )
• 2 8 bit digital-to-analog converters (DAC) (Use dacWrite(pin value); in Arduino IDE);
• Two I2C interfaces

Boot

Modes:

• EN: Connect to RTS
• GPIO0: Low = serial bootloader, High = boot from FLASH, internal pullup so default is FLASH. Connect to Serial DTR
• GPIO2: Must float or be low for serial bootloader. In FLASH mode (GPIO0 high) it is available.
• GPIO5: Outputs PWM signal at boot
• GPIO12: Selects voltage of FLASH. Low = 3.3V, High = 1.8V. Internal pull down, 1.8V is default.
• GPIO15: Low = no boot messages. High = boot messages at 115200bps. Internal pull UP, defaults on.

Arduino IDE Setup

Add https://dl.espressif.com/dl/package_esp32_index.json under File / Preferences / Additional boards manager. Then install from Tools / Boards: / Boards Manager (search for ESP32).

See also:

• https://microide.com/ An IDE hosted in the ESP32.+
• https://maakbaas.com/esp8266-iot-framework/logs/https-requests/ How to do secure HTTPS Requests to Any URL.
• https://mobile.twitter.com/cibomahto/status/1226901739472707584 You can use the SD card slot to connect a JTAG debugger.+
• https://github.com/quozl/cforth-1/blob/esp32/README.md Standards based FORTH for the ESP32 using raw C (not Arduino)+
• https://youtu.be/psMqilqlrRQ?t=611 Using PlatformIO^ in VSCode ^ with ESP-Prog ^ hardware jtag debugger ^ to single step, watch, run to break-points, etc... on the ESP32.
  https://medium.com/@manuel.bl/low-cost-esp32-in-circuit-debugging-dbbee39e508b Seems to be the best guide.
  0. Purchase ESP-PROG JTAG Debugger ^ ^ ^
  1. Install VS Code:
  https://code.visualstudio.com/
  2. Install PlatformIO:
  https://docs.platformio.org/en/latest/ide/vscode.html#installation
  Note: Despite them not mentioning it, you have to restart VSCode, and then there is a LONG period of downloading things and requesting permissions to modify your computer and so on. And then restarting VSCode again.
  3. Connect TCK, TMI, TDI, and TDO from ESP-Prog to ESP-32 (see ESP32 Pinout here and silkscreen bottom of ESP-Prog)
  4. Install drivers for FTDI chip on ESP-Prog
  https://www.ftdichip.com/Drivers/VCP.htm
  5. Connect ESP-Prog and insure drivers are found.
  6. Remove the default driver from ONE of the com ports of the ESP-Prog via Zadig (select "Options" and check "List All Devices", select "Dual RS232-HS (Interface 0)", click "Replace driver").
  In Device Manager, you should see:
  - Under Ports (COM & LPT) should should see a Silicon Labs CP2102 (for the ESP-32 USB connection) and a "USB Serial Port" (for the ESP-Prog connection).
  - Under "Universal Serial Bus controllers" the "USB Serial Converter B" should remain (the "A" should disappear on this step)
  - Under "Universal Serial Bus devices" you should see "Dual RS232-HS (Interface 0)"
  7. In VSCode, open a new Platform IO project, and in the platform.ini file, add:

  debug_tool = esp-prog
  debug_init_break = tbreak setup
  

  
  8. main.cpp should have the standard blink code or something else simple.
  9. Select the correct device from the status line at the very bottom. You may also need to adjust the com port. For some reason, the device is not correctly identified.
  Serial monitor may be opened from the status line. Select the port of the ESP-32 (the Silicon Labs one) but this will cause the debugger to lose control if it's running. You must open the monitor first, then start debugging.

• https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf Datasheet.+
• https://docs.espressif.com/projects/esp-idf/en/latest/get-started/get-started-devkitc.html Standard dev kit from Espressif.
  
  Pin-out in google spreadsheet
  Note: there is no LED on a data pin. So "Hello World!" needs external hardware or use serial.

  +

• https://github.com/espressif/arduino-esp32 Supported by the Arduino IDE for easy programming. Note: Some functions (most notably analogWrite, may not be supported in the same way. Other capabilities exist, e.g. dacWrite for true DAC analog output vs PWM) Add https://dl.espressif.com/dl/package_esp32_index.json under File / Preferences / Additional boards manager. Then install from Tools / Boards: / Boards Manager (search for ESP32).+
• https://techtutorialsx.com/2018/08/14/esp32-async-http-web-server-websockets-introduction/ While the standard ESPAsyncWebServer does work on the ESP32, the author does not support the Arduino IDE for it's use, preferring PlatformIO. The the examples for web servers do not work in the Arduino IDE. However, this page provides a series of examples (See "Related Posts") which document how to make it work. e.g. a simple web server via access point:

  #include "WiFi.h"
  #include "ESPAsyncWebServer.h"
   
  const char *ssid = "MyESP32AP";
  const char *password = "testpassword";
   
  AsyncWebServer server(80);
   
  void setup(){
    Serial.begin(115200);
   
    WiFi.softAP(ssid, password);
   
    Serial.println();
    Serial.print("IP address: ");
    Serial.println(WiFi.softAPIP());
   
    server.on("/hello", HTTP_GET, [](AsyncWebServerRequest *request){
      request->send(200, "text/plain", "Hello World");
    });
   
    server.begin();
  }
   
  void loop(){}