ESP32-S3 SPI Nand/SD SdFat Format for Fat16 recipe

[fcohen]

SdFat is an amazing open-source library for Arduino and ESP32 projects to use SD and Nand storage. It's been around since 2009. @greiman does an amazing job, even if SdFat is impossible to maintain. This is my contribution, a recipe for fellow ESP32 enthusiasts needing to format an SD for Fat16 over SPI. I wrote it for my Reflections open-source project. It uses an ESP32-S3 and Nand/SD.

Install SdFat

I used SdFat version 2.2.2. Open the Library Manager in Arduino IDE 2.2.1.

SdFatConfig.h Configuration

Make these changes to:

arduino/libraries/SdFat/src/SdFatConfig.h

Find this definition, change its value to 3

#define SPI_DRIVER_SELECT 3

Schematic

Sketch

Refer to the code
https://github.com/frankcohen/ReflectionsOS/Experiments/SdFat_ESP32_SPI_SD_NAND_Formatting

GPIO 12 is the chip-select for a TFT video display on the same SPI bus as the SD/Nand. This tells SdFat to disable it.

const int8_t DISABLE_CS_PIN = 12;

GPIO 15 is the chip-select for the SD/Nand.

#define SD_CS_PIN 15

ESP32 allows any GPIO pins to be an SPI bus. See Andreas Speiss video and spreadsheet to know the limitations. Reflection's board uses 35, 36, 37 for SPI between the SD/Nand and Display.

#define SPI_MOSI      35
#define SPI_MISO      37
#define SPI_SCK       36

Additional GPIO pins used by the Reflections board display.

#define Display_SPI_DC    5
#define Display_SPI_CS    12
#define Display_SPI_RST   0
#define Display_SPI_BK    6

Custom SPI connection class, begin method starts the SPI bus using the GPIO pins.

class MySpiClass : public SdSpiBaseClass {
...
SPI.begin(SPI_SCK, SPI_MISO, SPI_MOSI, -1);
...

SdFat sets SPI bus speed with the SD_SCK_MHZ macro. 50 works for my ESP32-S3-Mini-N1. I have found no clear method of determining the speed for a given board and SD/Nand component. Try lesser values. For example, 30, 20, 10.

#define SD_CONFIG SdSpiConfig(SD_CS_PIN, DEDICATED_SPI, SD_SCK_MHZ(50), &mySpi)

Sets the GPIO pins that support the SD/Nand and the display. These are specific to the Reflections board and you may change them for your board.

  pinMode(SD_CS_PIN, OUTPUT );
  digitalWrite(SD_CS_PIN, LOW);

  pinMode(Display_SPI_CS, OUTPUT);
  digitalWrite(Display_SPI_CS, LOW);

  pinMode(Display_SPI_DC, OUTPUT);
  digitalWrite(Display_SPI_DC, HIGH);

  pinMode(Display_SPI_RST, OUTPUT);
  digitalWrite(Display_SPI_RST, HIGH);

  pinMode(Display_SPI_BK, OUTPUT);
  digitalWrite(Display_SPI_BK, LOW);

Arduino IDE 2.x settings

Using Arduino IDE 2.x, use Tools menu options:

Board: ESP32S3 Dev Module
USB CDC On Boot: Enabled
Core Debug Level: Error
USB DFU On Boot: Disabled
Erase All Flash Before Sketch Upload: Disabled
Events Run On: Core 1
Flash Mode: QIO 80 Mhz
Flash Size: 8 MB (64MB)
JTAG Adapter: Integrated USB JTAG
Arduino Runs On: Core 1
USB Firmware MSC On Boot: Disabled
Partition Scheme: Defaults 4MB with Spiffs (1.2 MB APP/1.5MB SPIFFS)
PSRAM: Disabled
Upload Mode: UART0/Hardware CDC
Upload Speed 921600
USB Mode: Hardware CDC and JTAG

JCUSB, USB, JTAG Debugging, Connection

Connect your computer to an ESP32-S3 using a technique I call JCUSB. JCUSB is short for S3 + USB + CDC + OpenOCD + Arduino IDE. Only ESP32-S3 and its successors support JCUSB - it won't work on ESP32 and ESP32-S2. JCUSB uses a custom USB cable to connect an ESP32 to a Windows or MacOS computer. Details here

Compile and Run

Once you customize the above values, compile and upload the code. Then open the Serial Monitor, set the connection speeed to 115200, follow the on-screen instructions.

Here is an example. I ran this on my MacOS laptop using Arduino IDE 2.2.1.

SdFat version: 2.2.2

Disabling SPI device on pin 12

Assuming the SD chip select pin is: 15
Edit SD_CS_PIN to change the SD chip select pin.
Done

type any character to start

What May Go Wrong

SdFat works with a lot of hardware and SD cards, and it is possible it will not work with yours.

• SPI bus speed. SdFat sets SPI bus speed with the SD_SCK_MHZ macro. 50 works for my ESP32-S3-Mini-N1. I have found no clear method of determining the speed for a given board and SD/Nand component. Try lesser values. For example, 30, 20, 10.

• SD card won't format. Usually because it is broken. Or maybe partially zapped from static electricity. Or it is a low quality SD card that works inconsistently.

• Conflicts with the board definitions. Check the pin use on your board.

In the event something goes wrong, SdFat's creator/maintainer does an amazing job at interacting with his community. I recommend you search the issues, and if you need to post an issue.

--

Frank Cohen, 2023
Reflections Project