ESP32

= General information and links

• https://en.wikipedia.org/wiki/ESP32

Adafruit HUZZA32

• https://en.wikipedia.org/wiki/Adafruit_Industries
• Adafruit HUZZAH32 – ESP32 Feather Board, https://www.adafruit.com/product/3405
• based on ESP-WROOM-32 module, uses ESP32-D0WDQ6 chip, https://en.wikipedia.org/wiki/ESP32

• board available from DigiKey quantity "hundreds" ~CAD$35
  • https://www.digikey.ca/product-detail/en/adafruit-industries-llc/3405/1528-2181-ND/7244967
  • https://www.digikey.ca/product-detail/en/adafruit-industries-llc/3591/1528-2514-ND/8119805

• Pinouts & etc: https://learn.adafruit.com/adafruit-huzzah32-esp32-feather/pinouts

• • USB power connector
  • connection for external 3.7 V battery, charged from USB
  • serial IO 3.3V RX+TX
  • 1x SPI (where is the rest?)
  • 1x I2C (where is the rest?)
  • 7 GPIO top, shared with 2 DACs and 6 ADCs
  • 7 GPIO bottom, shared with 7 ADCs and other functions
  • everything is 3.3V, *NOT* 5V safe
  • there is ADC1 and ADC2, not clear what it means, ADC voltage range not clear
  • ADC1 or ADC2 cannot be used with Wifi (this is unclear)
  • ESP32 SD card interface not connected
  • ESP32 serial IO connected to USB via USB-serial-bridge chip (the best I can tell)
  • power is USB with battery backup, one header pin provides regulated 3.3 V power to user (available current not clear, maybe 250 mA), battery voltage is on A13

• suggested use with Ardiuno BSP (not mongoose OS)
• module schematic: https://cdn-learn.adafruit.com/assets/assets/000/041/630/original/feather_schem.png?1494449413

ESP-WROOM-32 module

• ESP32 chip is a very basic microcontroller, CPU is done by same people who did MIPS CPUs.
• ESP32 is supported by "Mongoose OS", familiar with it as we already use the mongoose web server from same people.
• general page: https://www.espressif.com/en/products/hardware/modules
• product page: https://www.espressif.com/zh-hans/esp-wroom-32/resources (in Chineese)
• data sheet: https://www.espressif.com/sites/default/files/documentation/esp32-wroom-32_datasheet_cn.pdf (in Chineese)
• module data sheet: https://www.espressif.com/sites/default/files/documentation/esp32-wroom-32_datasheet_en.pdf (English)
• chip data sheet: https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf

• • ESP32-D0WDQ6 chip
    • Xtensa® 32-bit LX6 microprocessors. The internal memory includes:
    • 448 KB of ROM for booting and core functions.
    • 520 KB of on-chip SRAM for data and instructions.
    • 8 KB of SRAM in RTC, which is called RTC FAST Memory and can be used for data storage; it is accessed by the main CPU during RTC Boot from the Deep-sleep mode.
    • 8 KB of SRAM in RTC, which is called RTC SLOW Memory and can be accessed by the co-processor during the Deep-sleep mode.
    • 1 Kbit of eFuse: 256 bits are used for the system (MAC address and chip configuration) and the remaining 768 bits are reserved for customer applications, including flash-encryption and chip-ID.
  • Recommended OS is FreeRTOS with LwIP
  • Wifi 802.11 b/g/n (802.11n up to 150 Mbps), at 2.5 GHz
  • Bluetooth v4.2 BR/EDR and BLE specification
  • power 3.3 V, 80 mA typical, up to 500 mA
  • pins connected to internal SPI flash: SCK/CLK, SDO/SD0, SDI/SD1, SHD/SD2, SWP/SD3 and SCS/CMD
  • pins MTDI, GPIO0, GPIO2, MTDO, GPIO5 are ”GPIO_STRAPPING" set the boot mode

Information from adafruit: https://www.adafruit.com/product/3405 and https://learn.adafruit.com/adafruit-huzzah32-esp32-feather

  - 240 MHz CPU, 520 kbytes SRAM, Wifi, Bluetooth, 4 Mbyte flash, interface for SD card.
  - 3x UART
  - 3x SPI
  - 2x I2C
  - 12 ADC inputs
  - 2 DAC
  - more goodies
  - everything is 3.3V, *NOT* 5V safe