ESP32

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= General information and links

Adafruit HUZZA32

    • 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

ESP-WROOM-32 module

Information from the data sheets:

ESP32-D0WDQ6 chip

  • dual 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.
  • 8 MB or 4 MB QSPI SRAM or Flash (this is the 4 Mbyte flash on the WROOM module?)
  • 18 channels of 12-bit SAR ADC, sampling: RTC 200 ksps, DIG 2 Msps, range 0..2450 mV, 6% variation between chips, see data sheet about calibration
    • ADC1 ch0..7, ADC2 ch0..9
  • Hall sensor (just one? which ADC channel?)
  • 2 channels of 8-bit DAC (GPIO25, 26)
  • 10 touch-sensor inputs T0..T9
  • ULP processor, RTC memory
  • 10/100 ethernet MAC
  • SD/SDIO/MMC controller 80 MHz, 1, 4 and 8 bits
  • SPI/SDIO slave interface
  • 3 channels of UART (U0 full modem control, U1, U2 RTS/CTS only)
  • 2 channels I2C master or slave
  • 2 channels I2S master or slave (I2S0, I2S1)
  • 8 channels infra red receive or transmit (RMT_SIG_IN0..7 and _OUT0..7)
  • 8 channels pulse counter
  • 3 channels PWM controller
  • 3 channels of SPI (SPI, HSPI, VSPI) master or slave
  • JTAG (4 pins)
  • 16 channels LED PWM
  • 228 signals, Table 25
  • 48 pins, IO_MUX table
  • conflict between ADC2 and Wifi (and Bluetooth?)

WROOM module

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

Arduino IDE

On RPi3 running CentOS 7.3 (ARM 32 bit)

  • install pyserial
#pip install pyserial ### no "pip"
#yum install python-pip ### "package not found" - no EPEL for ARM
curl "https://bootstrap.pypa.io/get-pip.py" -o "get-pip.py"
python get-pip.py 
pip install pyserial
  • install arduino:
    • download, untar: arduino-1.8.12-linuxarm.tar.xz
    • xz -d < arduino-1.8.12-linuxarm.tar.xz | tar xvf -
    • cd arduino-1.8.12
    • ./arduino ### it will bomb because libXtst is missing:
    • yum install libXtst
  • install ESP32 BSP:
  • try a "hello world" example:
    • in arduino
    • go to File->Examples->Communication->ASCII table
    • go to Sketch, do Compile and Upload (ESP32 should be connected)
    • compile successful (remember to install pyserial!), download successul, after "reset using RTS" nothing happens
    • go to Tools->Serial monitor set speed to 9600, hit the reset button on the ESP32, it should start printing the ascii table
  • try TFT display example
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