eMMC/SD Card Example

Source: example/rt_device/emmc

Overview

This example demonstrates how to create partitions on eMMC or SD card, mount the elm (FAT) filesystem on the partitions, and perform file operations.

Supported Platforms

• sf32lb56-lcd_a128r12n1

• sf32lb56-lcd_n16r12n1

• sf32lb58-lcd_n16r64n4

• sf32lb58-lcd_a128r32n1_dsi

Usage Guide

The eMMC application creates partitions on the board’s TF card, mounts the filesystem (FAT format), and provides common file commands via the UART console.

df               - Show filesystem disk usage
mountfs          - Mount device to filesystem
mkfs             - Format disk with filesystem
mkdir            - Create a directory
pwd              - Print current working directory
cd               - Change working directory
rm               - Remove (unlink) files/directories
cat              - Concatenate files (create and write content)
mv               - Rename SOURCE to DEST
cp               - Copy SOURCE to DEST
ls               - List files and directories

Menuconfig Configuration

sdk.py menuconfig --board=56devkit_lcd  (replace with your board name)

1. Enable SDIO

2. For single-wire speed testing, enable SDMMC1_BUS_WIDTH_1_ONLY / SDMMC2_BUS_WIDTH_1_ONLY (disabled by default, 4-wire mode operation).

3. Enable and configure the SD device

Build and Flash

Follow these steps to build and flash the firmware:

scons --board=56_devkit_lcd -j8
build_56_board_lcd_hcpu\download.bat  (or uart_download.bat for serial download)

Two flashing methods are supported: J-Link and UART.

Expected Results

1. Mount success log (look for the highlighted areas in the image below)
   

2. File operations: use ls to list existing files/directories, mkdir <dir> to create a directory, cd into it, echo to create a text file and write content, cat to view file content, and pwd to check the current working directory.

Read/Write Speed Test

This example provides 4 commands for testing eMMC/SD card read/write speed. Output unit is Mb/s.

Basic Commands (fixed 512-byte blocks)

Command	Usage Example	Description
fs_write	fs_write /1.txt 4096	Write 4096 blocks of 512B (2MB) to a file, testing filesystem write speed
fs_read	fs_read /1.txt 4096	Read 4096 blocks of 512B (2MB) from a file, testing filesystem read speed

Parameter num is the number of 512B blocks. Total data size = num x 512B. For example, fs_write /1.txt 2048 writes 1MB, fs_write /1.txt 4096 writes 2MB.

Extended Commands (recommended)

Command	Usage Example	Description
fs_write_ex	fs_write_ex /1.txt 2m	Write specified amount of data, testing filesystem write speed
fs_read_ex	fs_read_ex /1.txt 2m	Read specified amount of data, testing filesystem read speed

Extended commands internally convert to 512B block counts and delegate to basic commands, providing more user-friendly unit parameters.

Parameter Description

• total_size: supports k/K (KB) and m/M (MB) units, e.g. 512k 1m 2m 4m 8m

Typical Speed Test Workflow

fs_write_ex /1.txt 2m      <- Write 2MB test data first
fs_read_ex  /1.txt 2m      <- Then read 2MB to measure read speed

Example Output

• Read/Write speed test results

07-10 15:26:59:328 TX:fs_write_ex /6.txt 2M 
07-10 15:27:02:279    cmd_fs_write_t path=/6.txt num=4096 blocks testtime=2718475.250000uS,speed_test=6.171554Mb/s
07-10 15:27:02:290    msh />msh />
07-10 15:28:14:246 TX:fs_read_ex /6.txt 2M 
07-10 15:28:14:748    cmd_fs_read_t  path=/6.txt num=4096 blocks testtime=496185.312500uS,speed_test=33.812401Mb/s
07-10 15:28:14:757    msh />msh />

Unexpected Results (logs)

Failure Causes and Solutions

1. If the log shows the following, first check whether a TF card is inserted, then verify that SD is enabled in menuconfig (refer to the menuconfig configuration section above):

rt_mmcsd_blk_device_create find [sd0] fail !!!

2. If the log shows the following, check whether a TF card is inserted:

[E/DFS] Device (root) was not found
[E/DFS] Device (misc) was not found

If the expected output does not appear, troubleshoot from the following aspects:

• Check whether hardware connections are correct

• Check whether the USB connector is loose

• Check whether the USB cable supports data transfer

• Check whether the TF card is functional