ESP32-I2C-HUB

Features

• ESP32 breakout board
  • Requires specific version of ESP32 board (marked ESP32 DEVKITV1 on bottom)
• GVS (Ground, Voltage, Signal) for all ESP32 pins
  • Useful guide to the pins
• 4-channel I2C Hub
  • TCA9544 - 4-Channel I2C and SMBus Multiplexer With Interrupt Logic
  • Isolated I2C channels
  • Interrupt for each I2C channel
  • I2C Channels can be independently powered with 3.3V or 5V
  • Jumper selectable I2C base address
• GVS (Ground, Voltage, Signal) for all ESP32 pins
• FTDI header
• SPI bus header
• 5V power source selection/distribution
  • 5V sources - USB, 5mm terminal block, DC jack
• On-board 3.3V power regulator (doesn't stress the ESP32 regulator)
• 95x95mm ODAS form factor
• 6-32 mounting holes

ESP32-WROOM-32 Module

• ESP32 DevKit ESP32-WROOM GPIO Pinout
• On board Blue LED = Arduino Pin 2

Module Features

• Architecture: Xtensa Dual-Core 32-bit LX6
• CPU frequency: up to 240MHz
• Total RAM available: 528KB (part of it reserved for system)
• BootROM: 448KB
• Internal FlashROM: none
• External FlashROM: code and data, via SPI Flash; usual size 4MB
• GPIO: 34 (GPIOs are multiplexed with other functions, including external FlashROM, UART, etc.)
• UART: 3 RX/TX UART (no hardware handshaking), one TX-only UART
• SPI: 4 SPI interfaces (one used for FlashROM)
• I2C: 2 I2C (bitbang implementation available on any pins)
• I2S: 2
• ADC: 12-bit SAR ADC up to 18 channels
• DAC: 2 8-bit DACs
• RMT: 8 channels allowing accurate pulse transmit/receive
• Programming: using BootROM bootloader from UART - due to external FlashROM and always-available BootROM bootloader, the ESP32 is not brickable

Connectors

H1 - 3.3V from on-board regulator Header

• Install jumper

• Alternate for 3.3V power is to install S to V jumper at 3.3V header position (bottom right)
  • H1 should not be installed for that case

H2 - 5V SRC Header

• 2x3 header
• Care must be taken to install the correct jumpers
• USB jumper sends out 5V when a USB cable is connected to the ESP32 module
• USB jumper sends 5V into the ESP32 module when there is no USB cable connected to the ESP32 module

Power from USB on ESP32 module

• Do not install FTDI jumper
• Do not install DCJ jumper
• Install USB jumper

Power from 5V jack

• Do not install FTDI jumper
• Install DCJ jumper
• Install USB jumper

Power from FTDI

• Unstall FTDI jumper
• Do not install DCJ jumper
• Install USB jumper

J2 - FTDI

• Rx0/Tx0 connect to the USB-Serial interface on the ESP32 module

J3 - I2C Mux Base Address Select Jumpers

• A0-A2
  • Install for 0
  • Remove for 1

J7 - I2C Interface

• Also goes to the I2C Hub chip

1. INT* (GPIO5)
2. SCL (GPIO22)
3. SDA (GPIO11)
4. VCC
5. GND

J4, J5, J6, J8 - I2C Power Select (Ports #0-#3)

• Selects 3.3V or 5V on I2C
• 1-2 = 3.3V
• 2-3 = 5V

J9, J10, J11, J12 - I2C interfaces #0-#3

1. GND
2. VCC
3. SDA
4. SCL
5. INT*

P1 - 5V Power

• 2x8 pin header

P8 - SPIbus connector

1. MISO
2. 3.3V
3. SCK
4. MOSI
5. n/c
6. GND

Left GVS connector

• Some GPIO pins have meaning during boot
• Gnd/3.3V/Signals

1. EN (Pull low to shut off 3.3V reg)
2. VP/GPI36 (Input only)
3. VN/GPI39 (Input only)
4. GPI34 (Input only)
5. GPI35/A7 (Input only)
6. P32/A4
7. P33/A5
8. P25/A8
9. P26/A9
10. P27/SCL
11. P14/SD_CLK
12. P12/SD_D2
13. P13/SD_D3
14. VUSB

Right GVS connector

• Some GPIO pins have meaning during boot
• Gnd/3.3V/Signals

1. P23/MOSI
2. SCL/RTS1
3. P1/TX
4. I3/RX
5. P21/SDA
6. P19/CTS0
7. P18/SCK
8. P5
9. P17/TX2
10. P16/RX2
11. P4/SD_D1
12. P2/SD_D0
13. P15/SD_CMD
14. 3.3V

Software Support

MicroPython

• MicroPython Homepage
  • Quick reference for the ESP32
  • General information about the ESP32 port
  • Getting started with MicroPython on the ESP32
• GitHub repo (MicroPython)
  • Examples (MicroPython)
  • Libraries (MicroPython)
• ESP-IDF Programming Guide
• FreeRTOS
• ESP32 DevKit v1
• ESP32 DEVKITV1 module schematics (also helpful discussion)
• LuaNode

MicroPython SD Card Support

• The MicroPython docs page is short on details on software support for SD cards
• There are other ports which support SD Cards
  • loboris port

sdcard support is included which uses esp-idf sdmmc driver and 
can work in SD mode (1-bit and 4-bit)  or in SPI mode (sd card can 
be connected to any pins).

• GPIO14 = SD_Card CLK = SCK
• GPIO15 = SD_Card CMD/DI = MOSI
• GPIO2 = SD_Card DATA0/DO = MISO
• GPIO13 = SD_Card DAT3 = CS

Arduino Programming

• Board : "DOIT ESP32 DEVKIT V1"

Schematic

• ESP32-I2C-HUB Schematic
• ESP32-WROOM-32 Darasheet
• ESP32 Module schematic

Assembly Sheet

• ESP32-I2C-HUB Assembly Sheet