MicroSD Cards and SDFS

[rsocor01]

mackrackit,

Thank you for your response.

SD cards have 9 pads.

All the MicroSD cards that I have seen so far have 8 pads. Look at the attached picture.



Can I use SDFS with MicroSD cards that have 8 pads? From searching in google, I found that these MicroSD cards can operate in two modes, SPI and SD modes. Please take a look at the attached pics.



What mode should I use? How do you relate the pin functions to the schematics in the SDFS help file?


Robert

[Normnet]

Just a guess but use an adapter and SPI mode is by far most common.

Norm

[mackrackit]

Doh.... I was thinking regular SD cards.

The only time I have used them was with an adapter so using one straight should not be a problem.

Looking at the pin outs between the two it appears pin 9 has been dropped and pin 1 is not used on the micros. Pin 2 on the micro is the same as pin 1 on the full size, I think. Just compare the pin names and functions between the two.

SPI.... That is what SDFS uses. The only option it hardware SPI or not. Testing for speed between the two I have not seen a difference. Hardware SPI on the chip I use is also one of the USART pins so I have been using software SPI.

[rsocor01]

Hi,

I will use the SPI mode for the SDFS as you guys suggested. I've already ordered my MicroSD socket from mouser. So, I will keep you posted if I get it to work or not.

About all the extra pins that the MicroSD card doesn't use like the WP, I guess that I can comment out these lines of code that I don't need in the SDFS program. I'm going to have to study this SDFS code to see how it works.

Robert

[mackrackit]

When not using Write Protect do a search through SDFS for "SD_WE" and comment out anything to do with it. It only shows up in about 6 places.
Comment this

SD_WE_TRIS = 1

And all occurrences of this

If (SD_WE) Then
        FAT_error = CE_WRITE_PROTECTED
        Return        ' Return Byte FAT_error.
    Endif

The PIC® pin assignments will look something like this

SDI        Var    PORTB.2    ' SPI data in SD #7
SDI_TRIS    Var    TRISB.2    ' SPI data in direction
SCL        Var    PORTB.1    ' SPI clock  SD #5
SCL_TRIS    Var    TRISB.1    ' SPI clock direction
SD_CS        Var    PORTB.3    ' SD card chip select SD #1
SD_CS_TRIS    Var    TRISB.3    ' SD card chip select direction
SD_CD        Var    PORTB.4    ' SD card detect
SD_CD_TRIS    Var    TRISB.4    ' SD card detect direction
SDO        Var    PORTC.7    ' SPI data out   SD #2
SDO_TRIS    Var    TRISC.7    ' SPI data out direction

If you are not using the hardware SPI from the PIC® and need to use other pins put this in your code

SDC_UseHardSPI = FALSE

If you run into problems let us know.

[rsocor01]

If you run into problems let us know.

Thank you. As soon as I get the parts, I will start playing with the SDFS and the MicroSD card. I am sure I will have some questions.

Robert

[rsocor01]

Hi,

I finally got the parts that I needed and started playing with SDFS. Since I'm running my 18F4550 at 3.3V I connected all the MicroSD card pins directly to the PIC. I did not install the 10k resistors since my configuration is a little bit different. Do I need to use these 10K resistors?

I ran the SDTEST.BAS and it worked. It created a file TEST1.TXT with the text "ABC". I could see the file in my cell phone that runs Windows Mobile 6.1. Now, I can't read this card in my Windows XP PC. Somehow, XP does not like FAT16 format in the SD cards. How do you read your SD files in your computer? Is there any work around for this? I don't want to install Win98 in one of my old computers just for this .

Robert