TABLE OF CONTENTS In this and the remaining chapters we will look at the design of more complex PIC18 microcontroller-based projects. This chapter discusses the design of Secure Digital (SD) memory card-based projects. The remaining chapters of the book describe the basic theory and design of projects based on the popular USB bus and CAN bus protocols.
Before going into the design details of SD card-based projects, we should take a look at the basic principles and operation of SD card memory devices. Figure 7.1 shows a typical SD card.
The SD card is a flash memory storage device designed to provide high-capacity, nonvolatile, and rewritable storage in a small size. These devices are frequently used in many electronic consumer goods, such as cameras, computers, GPS systems, mobile phones, and PDAs. The memory capacity of the SD cards is increasing all the time. Currently they are available at capacities from 256MB to 8GB. The SD cards come in three sizes: standard, mini, and micro. Table 7.1 lists the main specifications of the most common standard SD and miniSD cards.
| Standard SD | miniSD | |
|---|---|---|
| Dimensions | 32 24 2.1mm | 21.5 20 1.4mm |
| Card weight | 2.0 grams | 1.0 grams |
| Operating voltage | 2.7 ?3.6V | 2.7 ?3.6V |
| Write protect | yes | no |
| Pins | 9 | 11 |
| Interface | SD or SPI | SD or SPI |
| Current consumption | <75mA (Write) | <40mA (Write) |
SD card specifications are maintained by the SD...
