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How to read/write data from/to Multi-Media Card??

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brennbar67

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memory stick pro interface

Dear all,

Need help...

Anyone know how2 write a C program to read out the data from MMC or write a data to MMC??? :(
Because i'm not quite familar with FAT file system, i just know a bit only...

How to read out a data (assume 4 MBytes data) from MMC? How to determine the next cluster of the data and free cluster so that can write data into MMC?
 

how to read mmc

If you are using an AVR processor you might look at commercial libraries here:
**broken link removed**

Also search edaboard for "FAT16" and you might find some interesting links.

best regards
 

c program to write into and read from mmc card

Dear fir,

The website that u gave me i went through b4....it need to purchase.
But i'm not affort to buy it.... :( too expensive!

Got any other sources?
 

brennbar67 said:
Dear fir,

The website that u gave me i went through b4....it need to purchase.
But i'm not affort to buy it.... :( too expensive!

Got any other sources?

I wrote commercial libraries ...

Also check here:


best regards
 

There is two different subject:

1) Reading and writing a sector from or on MultiMediaCard.
2) Detecting file system structure and working with File System (FS)

if you do not need to store data in MultiMedia Card in FS (FAT16) format, it is not needed to leard about the second subject.

you can read/write MultiMedia Card by sending approprate commands to the card, download card spec and command list from this topic and read related topics:
 

Hello,
Which micro-controller are you using?
I have done it on PIC16F877A. IT has a lil problem - The MMC card accepts data in minimum size of 512bytes only. So I had to buffer the 512 bytes of data in a external EEPORM and then send it to the MMC each time. It is pretty simple to interface once you get the hang of it.
 

Hi,

I used that File System with 8051 core. I made small wave file player using it. Working fine. if u need help plz email me at gaurav.sarode at yahoo dot com.
 

I am going to use MMC/SD card in my project ( MCU=AVR ) but i am little confused in these memories , in speed part ...

i need something about 400KB Reading speed from card in multiple block reading ( continues ) but somewhere i have seen Read speed is less than what i want , for example in this link :
http://elm-chan.org/fsw/ff/img/rwtest.png


but here it is said that speed is up to 5MB/s Read speed :
**broken link removed**

is that much difference usual ?
and if kingston is true , 5 MB/s means 40 Mb/s , but the maximum speed for SD is 25 MHz in SD_specs ... , it means it is not achievable in SPI mode ? and we should use SD 4bit bus mode ?

i am going to use SPI mode for both MMC & SD .
somewhere it is said ( in datasheets ) data transfer rate is up to 20 Mb/s,
is data transfer rate different by data writing and reading rate ???

and at last , specifications of MMC/SD is different from Memory Stick pro/pro duo ?
if yes where can i get Stick memory specs , seems it is faster than others ....

i need little help in these different speed grades ...
 

Hi
If your microcontroller is AVR, you can use AVRLib

Regards
Muoinhohn
 

latecomer said:
Hello,
Which micro-controller are you using?
I have done it on PIC16F877A. IT has a lil problem - The MMC card accepts data in minimum size of 512bytes only. So I had to buffer the 512 bytes of data in a external EEPORM and then send it to the MMC each time. It is pretty simple to interface once you get the hang of it.

i have the 16f876a pic and i have the same problem. The sram memory in pic is only 384 bytes and i need 512 to write on the sd/mmc card. can i use the eeprom of this pic? or do i have to add other external eeprom? other than this how can i solve this little problem?:?:

thank you for your time.
 

Use an 18F PIC with 1K or more internal RAM or add an external eeprom.
Or you could waste 1/2 the MMC space and write 256 dummy bytes for every 256 real bytes or mirror the data.
 

thanks for your answer but i have another one

I want to write some data from the pic to the sd card using SPI but i want the written data to be acessible from a card reader. to do this i must write a fat32 code and a spi transfer code or if i just write the spi transfer code to write in each 512 bytes of the sd card this will be readable in the card reader? don't know if i made myself clear?

thanks
 

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