◎ STM32F > port to MMC/SD

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BASIC4MCU | ◎ STM32F | STM32 | port to MMC/SD

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작성자 키트 작성일2017-09-13 09:52 조회1,555회 댓글0건

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port to MMC/SD



Unfortunately, I can't make the modules pC/FAT and pC/FFS freely accessible. However, I can give here a simplified version of the MMC/SD-Card Ports on the SPI-connection for miscellaneous controller.
By using this ports you can use another FileSystem on this interface and with it accessing the MMC- and SD-Cards. Or, like my tests, a MMC/SD-to-USB adapter can be realized in software. This works like an USB-Device as MassStorage (removable media) on the PC and you have access to the MMC- and SD-cards like an professional adapter in hardware (only slower, since SPI-mode and software realization).

Here a overview over the SD-Card versions:

3660040649_5C9wnkRe_SDversions_small.png
SD card versions


Restrictions of the simplified MMC/SD-ports:
- no interrupt- or DMA-mode
- no detailed media infos
- no read / write in call-back mode
- no direct RTOS-support

pCFAT_Port_SPI
download simplified pC/FAT Ports to MMC/SD (as ZIP)

(with MMCplus/HD-MMC/M-Bridge/SDHC/SDXC support)
(with optional McEx/ASSD-support)


On a porting to further controllers, additional to the SPI-speed adaptation only some parameters of the hardware must be known and to setup. This are the used PIO-pins for WP (WriteProtect), CD (CardDetect) plus the correct settings for MOSI, MISO, SCLK and /SS. Additional the matching SPI-mode 3 must be enabled.


to used SPI-mode of the controller (master)
Following diagram shows the SPI-mode, that is required for the communication with MMC- and SD-cards in the SPI-mode:
SPI-master mode

To the topic "speed"
In the following table, all important parameters of here present MMC/MMCplus/M-Bridge/SD/SDHC-cards are listed as confrontation. This illustrates quite well that the performance statements of the manufacturers speed for MMC/SD-mode is only indirect/relative with the context in SPI-mode.
The paramters Nac and Nbs are from special interest.
- Nac = maximum cycles between Read_CMD and data
- Nbs = maximum cycles between Write_CMD+data and End-of-Busy
These parameters partly fluctuate very strongly between the different cards/manufacturers. They give an information about how fast read and write of the internal storage can be really. BUT! also these values represent the respective absolute maximum-worth. That is but also on the other hand, a card with high Nbs nevertheless can possibly be faster ready with a Write-CMD, as a card with lower Nbs. However yields these statements a tendency over the cycles at most possible/expected/permissible from the respective manufacturer.

 

 

pC_FAT MMC_SD_Port_1
Card

MMC
16MB

Infineon

MMC
32MB

Infineon

MMC
64MB

Transcend

MMC
128MB

SanDisk

MMC
1GB

Hama

MMCmicro
512MB

X4store

RS-MMC
32MB

SanDisk

MMCmobile
64MB

Transcend

MID-OID

01-0000

01-0000

06-0000

02-0000

48-FFFF

6F-0000

02-0000

2C-0000

maxclk

20MHz

20MHz

20MHz

20MHz

20MHz

20MHz

20MHz

20(26)MHz

usedclk*

8MHz

8MHz

8MHz

8MHz

8MHz

8MHz

8MHz

8MHz

Nac

10.012

10.012

10.012

10.012

800.000

50.000

100.000

50.000

Nbs

40.048

40.048

40.048

40.048

102.400.000

1.600.000

400.000

1.600.000

maxsectors

31.424

62.720

125.440

250.880

2.007.040

1.003.520

62720

125.440

sectorsize

512

512

512

512

512

512

512

512


 

pC_FAT MMC_SD_Port_2
Card

MMCmobile
512MB

Transcend

MMCmobile
1GB

extreme

MMCmobile
2GB
green
memory

MMCmobile
2GB

Kingston

MMCplus
512MB

Transcend

MMC
1GB

extreme

MMCplus
2GB

Transcend

MMCplus
4GB

Pretec

MID-OID

15-0000

00-0000

6F-0000

70-0000

1E-FFFF

4B-4342

1E-FFFF

19-5944

maxclk

20(26)MHz

20MHz

20(52)MHz

20(52)MHz

20(52)MHz

20(?)MHz

20(52)MHz

20(52)MHz

usedclk*

8MHz

8MHz

8MHz

8MHz

8MHz

8MHz

8MHz

8MHz

Nac

15.012

30.000

10.000

200.012

50.000

35.000

200.000

200.012

Nbs

1.921.536

480.000

1.280.000

25.601.536

1.600.000

1.120.000

6.400.000

25.601.536

maxsectors

1.003.520

1.935.360

1.945.600

1.983.488

990.208

2.022.912

1.981.952

1.988.096

sectorsize

512

512

1024

1024

512

512

1024

2048


 

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