I started on the SD Card portion of the project. The objective of this is to read and write to and from the card, and finally to download data from the network and store in SD Card. I started my research on SD Cards. From this study I found that there are three protocols for communicating with SD Cards. The most popular of which is the SD mode and the SPI mode. There are also two types of SD Cards when considered in terms of programming. The Version 1 and Version 2 cards each of which require a different sequence for sending the card initialization commands.
I searched for documentation on programming of SD Cards and found that the “SD Specifications, Part1, Physical Layer” obtained from https://www.sdcard.org/downloads/pls/simplified_specs/Part_1_Physical_Layer_Simplified_Specification_Ver_3.01_Final_100518.pdf to be a detailed documentation of card initialization is SPI mode. Another source of information was “ How to Use MMC/SDC” from the website: http://elm-chan.org/docs/mmc/mmc_e.html.