This is the mbed-os example for the SDBlockDevice (SDCard) block device driver. See the SDBlockDevice documentation for more information.
This guide reviews the steps to get the SDCard with FAT filesystem working on an mbed OS platform.
Please install mbed CLI.
This example can be used on an mbedos platform that:
- Has an on-board SDCard slot or,
- Is fitted with a CI Test Shield.
This document uses the K64F as an example. Simply change the relevant options (e.g. -m K64F) to be appropriate for your target.
From the command-line, import the example:
mbed import mbed-os-example-sd-driver
You should see:
[mbed] Importing program "mbed-os-example-sd-driver" from "https://github.com/ARMmbed/mbed-os-example-sd-driver" at latest revision in the current branch
[mbed] Adding library "mbed-os" from "https://github.com/ARMmbed/mbed-os" at rev #f4864dc6429e
Move into the newly created directory:
cd mbed-os-example-sd-driver
Invoke mbed compile, and specify the name of your platform and your favorite toolchain (GCC_ARM, ARM, IAR). For example, for the GCC_ARM toolchain:
mbed compile -m K64F -t GCC_ARM
Your PC may take a few minutes to compile your code. At the end, you see the following result:
[snip]
Compile [ 99.7%]: SDBlockDevice.cpp
Compile [100.0%]: SPIFBlockDevice.cpp
Link: mbed-os-example-sd-driver
Elf2Bin: mbed-os-example-sd-driver
+--------------------------+-------+-------+-------+
| Module | .text | .data | .bss |
+--------------------------+-------+-------+-------+
| Fill | 162 | 0 | 2514 |
| Misc | 53840 | 2284 | 1112 |
| drivers | 1130 | 0 | 64 |
| features/filesystem | 13379 | 0 | 550 |
| features/storage | 42 | 0 | 184 |
| hal | 450 | 0 | 8 |
| platform | 2497 | 20 | 582 |
| rtos | 149 | 4 | 4 |
| rtos/rtx | 6143 | 20 | 6870 |
| targets/TARGET_Freescale | 12888 | 12 | 384 |
| Subtotals | 90680 | 2340 | 12272 |
+--------------------------+-------+-------+-------+
Allocated Heap: 24576 bytes
Allocated Stack: unknown
Total Static RAM memory (data + bss): 14612 bytes
Total RAM memory (data + bss + heap + stack): 39188 bytes
Total Flash memory (text + data + misc): 94060 bytes
Image: .\BUILD\K64F\GCC_ARM\mbed-os-example-sd-driver.bin
This example has been run on a K64F with the following pre-formatted microSDHC cards:
- Kingston 2GB mircoSDHC card.
- Kingston 8GB mircoSDHC card.
- SanDisk 16GB mircoSDHC ultra card.
If the card requires formatting then the following procedure is known to work:
- Insert microSD card into SD adapter in USB stick (or similar) so the microSD card can be insert into windows PC.
- Within file explorer, right click/Format on the USB drive.
- Select FAT32, 4096 cluster size, Quick Format.
- Format the drive.
The microSD card should then be ready for use in the K64F. Insert the formatted card into the SDCard slot on the K64F PCB.
Copy the binary from <root_dir>/mbed-os-example-sd-driver/BUILD/K64F/GCC_ARM/main.bin to the K64F:
- Connect your mbed device to the computer over USB.
- Copy the binary file to the mbed device.
- Press the reset button to start the program.
- Open the UART of the board in your favorite UART viewing program. For example,
screen /dev/ttyACM0.
You see the following output:
After connecting a serial console and resetting the target, the following trace should be seen:
Welcome to the filesystem example.
Opening a new file, numbers.txt. done.
Writing decimal numbers to a file (20/20) done.
Closing file. done.
Re-opening file read-only. done.
Dumping file to screen.
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
EOF.
Closing file. done.
Opening root directory. done.
Printing all filenames:
numbers.txt
Closeing root directory. done.
Filesystem Demo complete.
The standard way to test is with the mbed CI Test Shield plugged into the
target board. This pin mapping for this configuration is parameterised in
the mbed_app.json file.
The following is an example of the mbed_app.json file available in the repository:
{
"config": {
"UART_RX": "D0",
"UART_TX": "D1",
"DIO_0": "D0",
"DIO_1": "D1",
"DIO_2": "D2",
"DIO_3": "D3",
"DIO_4": "D4",
"DIO_5": "D5",
"DIO_6": "D6",
"DIO_7": "D7",
"DIO_8": "D8",
"DIO_9": "D9",
"SPI_CS": "D10",
"SPI_MOSI": "D11",
"SPI_MISO": "D12",
"SPI_CLK": "D13",
"I2C_SDA": "D14",
"I2C_SCL": "D15",
"I2C_TEMP_ADDR":"0x90",
"I2C_EEPROM_ADDR":"0xA0",
"AIN_0": "A0",
"AIN_1": "A1",
"AIN_2": "A2",
"AIN_3": "A3",
"AIN_4": "A4",
"AIN_5": "A5",
"AOUT" : "A5",
"PWM_0": "D3",
"PWM_1": "D5",
"PWM_2": "D6",
"PWM_3": "D9",
"DEBUG_MSG": 0,
"DEVICE_SPI": 1,
"FSFAT_SDCARD_INSTALLED": 1
},
"target_overrides": {
"DISCO_F051R8": {
"SPI_MOSI": "SPI_MOSI",
"SPI_MISO": "SPI_MISO",
"SPI_CLK": "SPI_SCK",
"SPI_CS": "SPI_CS"
},
"K20D50M": {
"SPI_MOSI": "PTD2",
"SPI_MISO": "PTD3",
"SPI_CLK": "PTD1",
"SPI_CS": "PTC2"
},
"KL22F": {
"SPI_MOSI": "PTD6",
"SPI_MISO": "PTD7",
"SPI_CLK": "PTD5",
"SPI_CS": "PTD4"
},
"KL25Z": {
"SPI_MOSI": "PTD2",
"SPI_MISO": "PTD3",
"SPI_CLK": "PTD1",
"SPI_CS": "PTD0"
},
"KL43Z": {
"SPI_MOSI": "PTD6",
"SPI_MISO": "PTD7",
"SPI_CLK": "PTD5",
"SPI_CS": "PTD4"
},
"KL46Z": {
"SPI_MOSI": "PTD6",
"SPI_MISO": "PTD7",
"SPI_CLK": "PTD5",
"SPI_CS": "PTD4"
},
"K64F": {
"SPI_MOSI": "PTE3",
"SPI_MISO": "PTE1",
"SPI_CLK": "PTE2",
"SPI_CS": "PTE4"
},
"K66F": {
"SPI_MOSI": "PTE3",
"SPI_MISO": "PTE1",
"SPI_CLK": "PTE2",
"SPI_CS": "PTE4"
},
"LPC11U37H_401": {
"SPI_MOSI": "SDMOSI",
"SPI_MISO": "SDMISO",
"SPI_CLK": "SDSCLK",
"SPI_CS": "SDSSEL"
},
"LPC2368": {
"SPI_MOSI": "p11",
"SPI_MISO": "p12",
"SPI_CLK": "p13",
"SPI_CS": "p14"
},
"NUCLEO_L031K6": {
"SPI_MOSI": "SPI_MOSI",
"SPI_MISO": "SPI_MISO",
"SPI_CLK": "SPI_SCK",
"SPI_CS": "SPI_CS"
},
"nRF51822": {
"SPI_MOSI": "p12",
"SPI_MISO": "p13",
"SPI_CLK": "p15",
"SPI_CS": "p14"
},
"RZ_A1H": {
"SPI_MOSI": "P8_5",
"SPI_MISO": "P8_6",
"SPI_CLK": "P8_3",
"SPI_CS": "P8_4"
}
}
}
Note the following things about the mbed_app.json file:
-
The
mbed_app.jsonfile is used to define target specific symbols for the SPI pins connecting the SDCard slot to the target MCU:- "SPI_CS". This is the Chip Select line.
- "SPI_MOSI". This is the Master Out Slave In data line.
- "SPI_MISO". This is the Master In Slave Out data line.
- "SPI_CLK". This is the serial Clock line.
-
The default configuration defined in the "config" section is for the standard Arduino header pin mappings for the SPI bus. The "config" section defines a dictionary mapping functional names to target board Arduino header pins:
- "SPI_CS": "D10". This causes the MBED_CONF_APP_SPI_CS symbol to be defined in mbed_config.h as D10, which is used in the filesystem test implementation. D10 is defined in the target specific PinNames.h file.
- "SPI_MOSI": "D11". This causes the MBED_CONF_APP_SPI_MOSI symbol to be defined in mbed_config.h.
- "SPI_MISO": "D12". This causes the MBED_CONF_APP_SPI_MISO symbol to be defined in mbed_config.h.
- "SPI_CLK": "D13". This causes the MBED_CONF_APP_SPI_CLK symbol to be defined in mbed_config.h.
-
The
"target_overrides"section is used to override the "SPI_xxx" symbols for specific target boards, which may have an SDCard slot, for example. This is the case for the K64F, where the "SPI_xxx" are mapped to the pin names for the on-board SDCard."K64F": { "SPI_MOSI": "PTE3", "SPI_MISO": "PTE1", "SPI_CLK": "PTE2", "SPI_CS": "PTE4" } -
Thus, in the absence of any target specific definitions in the
"target_overrides"section, all boards will default to using the Arduino header configuration. For those platforms with a"target_overrides"section then this configuration will be used in preference. -
Hence in the case that you want to test a platform with an SDCard inserted into a fitted CI test shield (rather than the on-board SDCard slot) and there is a
"target_overrides"section present in thembed_app.jsonfile, you must then delete the"target_overrides"section before building. This will result in the default configuration being used (suitable for the CI Test Shield). -
Note when inserting the v1.0.0 CI Test Shield into the Arduino header of the target platform, the shield pins D0 and D1 should be bent to be parallel to the shield PCB so they are not inserted into the Arduino header. This is because some boards use the same UART on DAPLINK and D0/D1, which means the serial debug channel breaks and hence the mbed greentea test suite will not work correctly. This is mainly on older ST boards and should not be a problem on
K64F,NUCLEO_F429ZIandUBLOX_EVK_ODIN_W2. Note also that the v2.0.0 CI Test Shield doesn't suffer from this problem and the pins don't need to be bent. -
When inserting the SDCard into the card slot on the CI test shield, make sure the card is fully inserted. On insertion, there should be a small clicking sound when the card registers, and the back edge of the card should protrude no more than ~1mm over the edge of the CI test shield PCB. If the SDCard fails to register, try gently pushing the metal flexible strip in the shape of a spade at the top edge of the SDCard metal slot casing with a pair of tweezers, bending it a little to lower it into the slot casing. This helps with the insertion mechanism.
Figure 1. The figure shows the K64F platform with the CI shield fitted.
The above figure shows the K64F with the v1.0.0 CI test shield fitted. Note:
- The pins D0/D1 (top right of CI test shield) are bent sideways so as not to insert into the header.
- The SDCard is fully inserted into the slot and overhangs the PCB by ~1mm.
- Make sure
mbed-cliis working correctly and its version is newer than1.0.0.
mbed --version
If not, update it:
pip install mbed-cli --upgrade
The software is provided under Apache-2.0 license. Contributions to this project are accepted under the same license. Please see contributing.md for more info.
This project contains code from other projects. The original license text is included in those source files. They must comply with our license guide.
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