Hello community members.
I have recently started working with SD card using Microchip ARM based uC SAM4. So far I have managed to initialize the HSMCI interface of SAM4 and SD card is also initialized and has responded with the card capacity and the RCA (Relative Card Address). What I need to do now is read and write on the SD card. For this purpose I have extracted some functions implemented in the Atmel Studio examples. What I am confused about is how is the addressing done for the SD card, I realize that the card responds with a RCA but afterwards how is the addressing tracked to read and write data over the SD card and if we want to read data previously written how do we know where to read it from. I understand these are very basic questions but as I mentioned I am very new to this and need assistance.
Thanks in advance.
Regards,
Owais.
Hello Techguys,
Thank for your response. Actually I started with an example project in Atmel Studio for SAM4S-EK2 board for unit test of SD/MMC/SDIO card. So the example first identifies the type of card inserted and then initializes it accordingly. I have extracted the initialization code from this example and now I can create my own project and initialize the card and it returns the correct card size as well as RCA (Relative Card Address). What I need to do now is get the SD card related functions or in this case more specifically the HSMCI (High Speed Mutimedia Card Interface) functions to read and write blocks and integrate them into FreeRTOS+FAT SL. Since the example provided by FreeRTOS+FAT SL is for RAM, i have to adjust the functions and insert functions related to SD card. the example I used is documented in the following link:
http://asf.atmel.com/docs/3.19.0/common.components.memory.sd_mmc.unit_tests.sam4s_ek2/html/index.html
I am already following a thread related this matter on another blog dedicated for FreeRTOS. it would be helpful if someone here could also help me in this regard or if someone has already done this kind of thing before please do share your experience.
Owais