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Easy Basics: Project 072y ESP32 Development board with SD card module

of Acoptex.com in ESP8266 ESP-32

Basics: Project 072y

Project name: ESP32 Development board with SD card module

Tags: ESP32 Dev Module, ESP32 development board, ESP32 Development board with WiFi and Bluetooth, ESP32-DevKitC V4 development board, ESP-WROOM-32 module with ESP32‑D0WDQ6 chip, Espressif Systems, ESP32-based development board, ESP32 modules, ESP32-WROOM-32, ESP32-WROOM-32U, ESP32-WROOM-32D, ESP32-SOLO-1, USB-UART bridge, IOT, ESP-WROOM-32 Dev Module, ESP32 DEVKITV1, Installing the ESP32 Board in Arduino IDE, Uploading sketch, SD card module, Micro SD card module,

Attachments:  library1 and sketch1

In this project, you need these parts :

1. ESP32 development board with WiFi and Bluetooth and USB A / micro USB B cable 1 pc

2.Arduino IDE ( you can download it from here  )

3.Jumper cables F-F

4. Micro SD card with adapter 1 pc

5. SD card module or Micro SD card module 1 pc

 or 

General

We will learn how to connect SD card module with the ESP32 development board and use the SD card module to read and write files on it. 

The use of SD card or Micro SD card is to store the data. Because SD card or Micro SD card has big capacity so it can store more data comparing to EEPROM. Why does SD card or Micro SD card useful for ESP32 development board? As you know ESP8266 and ESP32 are more popular with IoT applications. They can keep the roles such as: 

  • A client to collect data from sensors such as temperature or humidity or log of an event, and save these data into SD card or Micro SD card.
  • A web server using SD card or Micro SD card to store web pages, images, javascript and so on that will be returned to the client requests.

Project steps are:

  1. ESP32 development board connects to SD card or Micro SD card;
  2. Sends to the SD card or Micro SD card the list all files and folders in it and print to Serial Monitor;
  3. Opens a file named logging.txt to write Hello world! text to it and closes it;
  4. Opens logging.txt file again for reading the text then prints to Serial Monitor and closes it.

There are a lot of different development boards made. You can find more information about them here

Understanding the SD card module

You can read more about it here.

Understanding the ESP32 Development board with WiFi and Bluetooth

We will discuss here an Espressif Systems products. Our development board is using ESP-WROOM-32 module from Espressif Systems.

Espressif offers a wide range of fully-certified Wi-Fi & BT modules powered by their own advanced SoCs.

1. Dual-core Modules with Wi-Fi & Dual-mode Bluetooth

Features

  • Two independently-controlled CPU cores with adjustable clock frequency, ranging from 80 MHz to 240 MHz
  • +19.5 dBm output at the antenna ensures a good physical range
  • Classic Bluetooth for legacy connections, also supporting L2CAP, SDP, GAP, SMP, AVDTP, AVCTP, A2DP (SNK) and AVRCP (CT)
  • Support for Bluetooth Low Energy (BLE) profiles including L2CAP, GAP, GATT, SMP, and GATT-based profiles like BluFi, SPP-like, etc
  • Bluetooth Low Energy (BLE) connects to smart phones, broadcasting low-energy beacons for easy detection
  • Sleep current is less than 5 μA, making it suitable for battery-powered and wearable-electronics applications
  • Integrates 4 MB flash
  • Peripherals include capacitive touch sensors, Hall sensor, low-noise sense amplifiers, SD card interface, Ethernet, high-speed SPI, UART, I2S and I2C
  • Fully certified with integrated antenna and software stacks

2. Single-core Modules with Wi-Fi & Dual-mode Bluetooth

Features

  • High-performance 160 MHz single-core CPU
  • +19.5 dBm output at the antenna ensures a good physical range
  • Classic Bluetooth for legacy connections, also supporting L2CAP, SDP, GAP, SMP, AVDTP, AVCTP, A2DP (SNK) and AVRCP (CT)
  • Support for Bluetooth Low Energy (BLE) profiles including L2CAP, GAP, GATT, SMP, and GATT-based profiles like BluFi, SPP-like, etc
  • Bluetooth Low Energy (BLE) connects to smart phones, broadcasting low-energy beacons for easy detection
  • Sleep current is less than 5 μA, making it suitable for battery-powered and wearable-electronics applications
  • Peripherals include capacitive touch sensors, Hall sensor, low-noise sense amplifiers, SD card interface, Ethernet, high-speed SPI, UART, I2S and I2C
  • Fully certified with integrated antenna and software stacks

3. Single-core Modules with 802.11b/g/n 2.4 GHz Wi-Fi

Features

  • High-performance 160 MHz single-core CPU
  • +19.5 dBm output at the antenna ensures a good physical range
  • Sleep current is less than 20 μA, making it suitable for battery-powered and wearable-electronics applications
  • Peripherals include UART, GPIO, I2C, I2S, SDIO, PWM, ADC and SPI
  • Fully certified with integrated antenna and software stacks

There are different development Boards made by Espressif Systems and other manufacturers. We will publish some information about Espressif Systems boards but you can also find out more information about other development boards here.

1. 2.4 GHz Wi-Fi & BT/BLE Development Boards

Features

  • PC connectivity: USB
  • Power supply options: USB (by default), or 5V/GND header pins, or 3V3/GND header pins
  • SDK: ESP-IDF source code and example applications

2. 2.4 GHz Wi-Fi Development Boards

Features

  • PC connectivity: USB
  • SDK: ESP8266 SDK source code and example applications

3. 2.4 GHz Wi-Fi + BT/BLE + Sensor Development Boards

Features

  • PC connectivity: USB
  • SDK: ESP-IOT-SOLUTION source code and example applications

You can find more information (datasheets, schematics, pins descriptions, functional desgn descriptions) about each board by pressing Getting started link close to each board here.

ESP32 chip

ESP32 is a series of low cost, low power system on a chip microcontrollers with integrated Wi-Fi and dual-mode Bluetooth. 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.

ESP32 can perform as a complete standalone system or as a slave device to a host MCU, reducing communication stack overhead on the main application processor. ESP32 can interface with other systems to provide Wi-Fi and Bluetooth functionality through its SPI / SDIO or I2C / UART interfaces.

ESP32 is highly-integrated with in-built antenna switches, RF balun, power amplifier, low-noise receive amplifier, filters, and power management modules. ESP32 adds priceless functionality and versatility to your applications with minimal Printed Circuit Board (PCB) requirements.

ESP32 is capable of functioning reliably in industrial environments, with an operating temperature ranging from –40°C to +125°C. Powered by advanced calibration circuitries, ESP32 can dynamically remove external circuit imperfections and adapt to changes in external conditions.

Engineered for mobile devices, wearable electronics and IoT applications, ESP32 achieves ultra-low power consumption with a combination of several types of proprietary software. ESP32 also includes state-of-the-art features, such as fine-grained clock gating, various power modes and dynamic power scaling.

Functional Block Diagram:

Features of the ESP32 include the following:

Processors:

  • CPU: Xtensa dual-core (or single-core) 32-bit LX6 microprocessor, operating at 160 or 240 MHz and performing at up to 600 DMIPS
  • Ultra low power (ULP) co-processor
  • Memory: 520 KiB SRAM

Wireless connectivity:

  • Wi-Fi: 802.11 b/g/n
  • Bluetooth: v4.2 BR/EDR and BLE

Peripheral interfaces:

  • 12-bit SAR ADC up to 18 channels
  • 2 × 8-bit DACs
  • 10 × touch sensors (capacitive sensing GPIOs)
  • Temperature sensor
  • 4 × SPI
  • 2 × I²S interfaces
  • 2 × I²C interfaces
  • 3 × UART
  • SD/SDIO/CE-ATA/MMC/eMMC host controller
  • SDIO/SPI slave controller
  • Ethernet MAC interface with dedicated DMA and IEEE 1588 Precision Time Protocol support
  • CAN bus 2.0
  • Infrared remote controller (TX/RX, up to 8 channels)
  • Motor PWM
  • LED PWM (up to 16 channels)
  • Hall effect sensor
  • Ultra low power analog pre-amplifier

Security:

  • IEEE 802.11 standard security features all supported, including WFA, WPA/WPA2 and WAPI
  • Secure boot
  • Flash encryption
  • 1024-bit OTP, up to 768-bit for customers
  • Cryptographic hardware acceleration: AES, SHA-2, RSA, elliptic curve cryptography (ECC), random number generator (RNG)

Power management:

  • Internal low-dropout regulator
  • Individual power domain for RTC
  • 5uA deep sleep current
  • Wake up from GPIO interrupt, timer, ADC measurements, capacitive touch sensor interrupt

You can find ESP32 chip datasheet here, hardware design here, technical reference manual here.

Signals and connections of the SD card module

or 

Note: depending on the module you’re using, the pins may be in a different order.

VCC (5V)  - connect to 5V pin Arduino Uno. If it is just VCC pin and no 3V3 pin connect VCC to 3.3V pin of Arduino Board

3V3 (or 3.3V) - connect to 3.3V pin Arduino Uno

CS (or SS or D3) (Chip Select or Slave Select) - the pin on each device that the master can use to enable and disable specific devices

MOSI (or DI or SI or CMD) (Master Out Slave In) - The Master line for sending data to the peripherals

CLK (or SCK) (Serial Clock) - The clock pulses which synchronize data transmission generated by the master

MISO (or DO or SO) (Master In Slave Out) - The Slave line for sending data to the master

GND (or G) - ground

CD - this is the Card Detect pin. It shorts to ground when a card is inserted. You should connect a pull up resistor (10K or so) and wire this to another pin if you want to detect when a card is inserted. 

Signals and connections of the ESP32 Development board with WiFi and Bluetooth

You can find more information (datasheets, schematics, pins descriptions, functional desgn descriptions) about each board (made by Espresiff Systems) by pressing Getting started link close to each board here.

Let's check our development board - ESP32 DEVKITV1 with ESP-WROOM-32 module from Espressif Systems:

Pinout diagram for the ESP Wroom 32 breakout:

ESP32-WROOM-32 - ESP32-WROOM-32 module soldered to the development board. Optionally ESP32-WROOM-32D, ESP32-WROOM-32U or ESP32-SOLO-1 module may be soldered instead of the ESP32-WROOM-32.

USB-UART Bridge - A single chip USB-UART bridge provides up to 3 Mbps transfers rates.

BOOT button - Download button: holding down the Boot button and pressing the EN button initiates the firmware download mode. Then user can download firmware through the serial port.

EN button - Reset button: pressing this button resets the system.

Micro USB Port - USB interface. It functions as the power supply for the board and the communication interface between PC and the ESP module.

TX0, TX2 - transmit pin. GPIO pin

RX0, RX2  - receive pin.  GPIO pin

3V3 (or 3V or 3.3V) - power supply pin (3-3.6V). 

GND - ground pin.

EN - Chip enable. Keep it on high (3.3V) for normal operation.

Vin - External power supply 5VDC.

Wiring

SD card or Micro SD card module     ESP32 development board

VCC                                3V3

GND                                G

SCK                                GPIO 18

MOSI                              GPIO 23

CS                                  GPIO 5

MISO                              GPIO 19

Step by Step instruction

The ESP32 is currently being integrated with the Arduino IDE like it was done for the ESP8266. There’s an add-on for the Arduino IDE that allows you to program the ESP32 using the Arduino IDE and its programming language.

1. Installing ESP32 add-on in Arduino IDE (Windows 10 OS)

  1. Download and install the latest Arduino IDE Windows Installer from arduino.cc
  2. Download and install Git and Git GUI from git-scm.com
  3. Search for Git GUI, right-click the icon and select “Run as administrator
  4. Select the Clone Existing Repository option.
  5. Select source and destination. Source Location: https://github.com/espressif/arduino-esp32.git
  6. Target Directory:C:/Users/[YOUR_USER_NAME]/Documents/Arduino/hardware/espressif/esp32
  7. Do not create the espressif/esp32 folders, because they will be created automatically.
  8. Click Clone to start cloning the repository.Wait a few seconds while the repository is being cloned.
  9. Open the folder: C:/Users/[YOUR_USER_NAME]/Documents/Arduino/hardware/espressif/esp32/tools
  10. Right-click the get.exe file and select “Run as administrator“.
  11. You will see that necessary files will be downloaded and upzipped. It will take some time.
  12. When get.exe finishes, you should see the following files in the directory.

2. Uploading sketch to ESP32 development board

  1. Most SD cards work right out of the box, but it's possible you have one that was used in a computer or camera and it cannot be read by the SD library. Formatting the card will create a file system that the Arduino can read and write to. It's not desirable to format SD cards frequently, as it shortens their life span. You’ll need a SD reader and computer to format your card. The library supports the FAT16 and FAT32 filesystems, but use FAT16 when possible. See additional info here.
  2. Format the SD card as FAT16 or FAT32. Insert the SD card in your computer. Go to My Computer and right click on the SD card. Select Format...  
  3. A new window pops up. Select FAT32, press Start to initialize the formatting process and follow the onscreen instructions.
  4. Insert the formatted SD card in the SD card module.
  5. Do wiring.
  6. Plug the ESP32 development board to your PC and wait for the drivers to install (or install manually any that might be required).
  7. Open Arduino IDE. 
  8. Open Boards manager. Go to Tools -> Board -> Boards Manager… (in our case it’s the DOIT ESP32 DEVKIT V1)
  9. Select COM port that the board is attached to (if you don’t see the COM Port in your Arduino IDE, you need to install the ESP32 CP210x USB to UART Bridge VCP Drivers)
  10. Compile and upload the sketch1 to your ESP32 development board. If everything went as expected, you should see a “Done uploading” message. (You need to hold the ESP32 on-board Boot button while uploading).
  11. Press the ESP32 on-board EN button to reboot it. 
  12. Open the Serial Monitor at a baud rate of 115200. 
    ESP32 development board connects to SD card or Micro SD card;
    Sends to the SD card or Micro SD card the list all files and folders in it and print to Serial Monitor;
    Opens a file named logging.txt to write Hello world! text to it and closes it;
    Opens logging.txt file again for reading the text then prints to Serial Monitor and closes it.
    ESP32 development board connects to SD card or Micro SD card;sends to the SD card or Micro SD card the list all files and folders in it and print to Serial Monitor;opens a file named logging.txt to write Hello world! text to it and closes it;opens logging.txt file again for reading the text then prints to Serial Monitor and closes it.

Code

The code is well explained. Please see the sketch attached.

The esp32_nanosdcard library supplies some classes and interfaces:

Class SD:

- SD.begin(uint8_t cs , int8_t mosi , int8_t miso , int8_t sck): initialize library with SPI pins

- SD.open(filename, FILE_WRITE): open file for writing

- SD.open(filename): open file for reading 

- SD.open("/"): open sd card at root “/”

Class File:

- openNextFile(): traverse the directory

- name(): get the name of file or directory

- isDirectory(): check if entry is directory

- size(): get size of file

- close(): close the opened entry

- println(text): write text to opened file

- available(): check data available for reading

- read(): if data is available then read data

- close(): close the opened file 

Summary

We have learnt how to connect SD card module with the ESP32 development board and use the SD card module to read and write files on it. 

Libraries

  • All libraries attached on the begining of this project description.
  • esp32_nanosdcard library included.Download, unzip  and add to libraries in our PC, for example C:\Users\toshiba\Documents\Arduino\libraries. This link you can find in Preferences of Adruino IDE program which installed in your PC. You can read more about library here.

Sketch

  • See attachments on the begining of this project


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Published at 08-09-2018
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