The USB Flash Drive referred in this manual contains USB Flash Drive, USB HD, USB Flash Memory, USB reader and so on. The SD card referred in this manual contains SD, MMC card, HC-SD card (with high capacity), TF card and so on. The manual mainly supplies commands of file manage control, uses to USB Flash Drive and SD card. SPI is a common communication protocol used by many different devices. For example, SD card reader modules, RFID card reader modules, and 2.4 GHz wireless transmitter/receivers all use SPI to communicate with microcontrollers. One unique benefit of SPI is the fact that data can be transferred without interruption.
If the SD card is formatted and a fixed length file is created (copy a blank file from the PC - IIRC there are 32MB files I created in the ZiCog thread). ZiCog locates the file under FAT16 and takes that address as the base and you access the file relatively (directly) from there. Originally heater used the SD card directly with no FAT16.
I have seen that for some SD cards maximum speed was about 1.33MHz and for some 20MHz. I assumed this speed was in the CSD register (TAAC value, as the TRAN_SPEED was the same on all the cards set at 25Mhz). However I realized its not true. I would really appreciate if someone can share their knowledge on this. Thanks! Introduction. There are many peripherals that can be added to a microprocessor over the I2C and SPI serial interfaces. These include atmospheric sensors, EEPROMS, and several types of display. The Pi Wedge helps access the I2C and SPI signals. This tutorial will walk you through getting the I2C and SPI interfaces of your Raspberry Pi working. . 214 424 296 380 3 80 224 165

spi flash vs sd card