Hi Forum Members,
First, I am Sorry, I am creating a new thread related to MMC Cards. Well the previous thread was for the CRC calculation (software), and this one is a hardware problem.

The connections are:
Main Board Interface MMC Card
CPU(P89C51RD2) => 74HC244 => CS,DI,CLK
CPU(P89C51RD2) <= 74HC244 <= DO (Through pullup 100k)
Power to CPU=5Vdc,
Power to MMC+74HC244+pullup resistor=3.0Vdc. (even tried by giving 3.3Vdc).


I am using the MMC card in SPI Mode. I wrote the code for SPI Port:
1. At power on, make all the pins high.
2. CS Make Low
3. Send the bytes 0x40,0x00,0x00,0x00,0x00,0x95 to MMC Card
4. Recieve the bytes.
5. Make CS high.

There is no activity on the DO (pin 7 of MMC). I checked it on the CRO, there is no activity. It remains tri-stated. I tried by using resistors from 10k to 1M, but nothing happens. The other signals from the CPU to Card are OK, checked them on a CRO.

The MMC Card is Fujitech 128M0341A (128MB). This card is working OK when placed in a Digital camera.
I have also tried by direct soldering on the MMC Card. Relax, the MMC Card is still working OK with a camera.


My queries:
1. Can I get the links to datasheet of the FujitechMMC Card. I have searched it on Google and got lots of links to specs of digital camera, but not got a link to the above data sheet.
2. Is there any mistake in the circuit?
3. I have given delays in the SPI core routines just to assure if the time delays are acting funny. But nothing happens on the DO pin.

Thanking you all,
With best regards from,
Mr. Kiran V. Sutar.

P.S. Sorry for generating 2 threads if in case I am causing any inconvenience to anybody. Next time I will take care.