Problem: Using MultiMediaCard in MMC mode

[leotim]

Hello all,

I use MMC in MMC mode (i.e. not in SPI mode). after power up i wait some milliseconds. then start the MMC clock with frequency of 240kHz and after one millisecond, i send CMD0, then CMD1. but in respons to CMD1 i receive OCR with busy bit cleared (0x00FF8000). it means that card is busy.

after sending CMD1 and receiving BUSY, the card does not respond to the CMD1 command nor to CMD2 any more.

I am using AT89C5132 that has an internal MMC controller.
I checked the correct format of the commands using oscilloscope.

is there any idea to solve this problem? i need to solve this problem as soon as possible.

 

[bobcat1]

Hi

Do the following :

1) check your power supply to be in range
2) Replace the MMC card with a known working one
3) Check your hardware connection to the MMC card
4) Replace the controller with a new one
5) Lower the CLK down to less the 100Khz

If notting helps you probbly issueing a software problem - check your software!

All the best

Bobi

 

[leotim]

Dear bobcat1,
Did you used AT89C5132 to read an MMC in MMC mode or did you read the MMC card in MMC mode (not SPI mode) forever?

1) My power supply is 3.12VDC (3mVp-p @6MHz)
2) The card works properly in a card reader: i can format it, create file, read it again.
3) it seems that there is no error in hardware connection. becauase i send CMD1 properly and receive the response with busy (=0x00FF8000). so the command to the card and the reponse from it will do.
4) i will check my firmware with a new board and new controller, but what problem you guess that is present?
5) i lowered the clock frequency to 80kHz

Regards

 

[leotim]

Excuse me: Power Supply Voltage is 3.12 VDC + (30mVp-p @6 MHz)

 

[gauravsarode]

Hi,

I want to use the same AT89C5132 with the MMC . Can you guide me in this? I am using MMC for first time.waitng for your reply.

 

[leotim]

you may use this circuit.
i you gained a good result, please tell me.

 

[netferry]

I use AT89c51SND1c and I want to interface also an new 512 A-Data MMC card in MMC mode but I can't get response to CMD1 command
Do you have any idea what should I pay attention in software?

Ferry

 

[leotim]

I use AT89c51SND1c and I want to interface also an new 512 A-Data MMC card in MMC mode but I can't get response to CMD1 command
Do you have any idea what should I pay attention in software?

Ferry

If your code (software) is matching MMC standards, (you may find this standard in edaboard or from MMC manufacturer site), then you should pay attention to your VCC. It may have some glitch (noise) that prevents MMC power-up completion.

Also another important issue you should pay attention to is the connection from microcontroller to MMC card (soldering and connector) specialy VCC connection. If there was non-perfect soldering (for example in microcontroller pins or conector pins) or weak connection between MultiMediaCard and its connector, this situation may occur. Because these conditions may prevent suppling a good VCC to MultiMediaCard. Use a high quality connector for MultiMediaCard specialy in development stages.

Hope this help.