This tutorial was specifically written around the microcontroller I am using, which is the ST upsd3334D microcontroller. Since it is fundamentally an 8052, you should be able to adapt this tutorial to your specific microcontroller; however, some of the Special Function Registers will probably be different. The upsd3334D is unique in that it is not only an 8052, but also a CPLD(Complex Programmable Logic Device) in the same part. The 8052 portion of the part is 3.3v and the CPLD portion is 5.0v. The hardware interface to the SD card is simple. The signals can connect directly to the 3.3v pins on the 8052, but I added 30 ohm resistors to reduce signal bounce.



In this tutorial, the SD memory card is attached to the 3.3v section of the micro, so no voltage shifting is necessary.

Remember: The SD memory card has a limited voltage range, so ALL signals to and from it are a maximum of 3.3v. If you connect 5.0v signals to the SD memory card, you might damage it.

Additionally, I am using the Keil development PK51 suite, which consists of the IDE (Integrated Development Environment), the C51 compiler, the AX51 assembler, and the LX51 link-loader. The version is 8.17a, but I believe any version should work.

If you would like to read more about CPLD’s, you can visit this link: http://en.wikipedia.org/wiki/CPLD

If you would like to read more about the processor I am using, you can visit this link: http://www.keil.com/dd/chip/3639.htm

Tutorial Index
Interface to Chan’s Library of functions	SD Card Initialization
Target development platform	Reading and Writing a single sector
Setting up the SPI port during startup.A51	Working with diskio.c
Global type definitions and variables	Pulling it all together
Basic SPI function	Index Page