Overview

The Secure Digital Host (SD Host) controller on CC3200 provides an interface to standard SD memory cards in 1-bit transfer mode and handles the SD protocol and data packing at the transmission level with minimum CPU intervention.

Application details

This application showcases the basic use case of initializing the controller to communicate with the attached card, reading and writing an SD card block using the internal controller buffer via DriverLib API(s). The demo includes extracting the card capacity, capacity class and SD version information and displaying it on the UART terminal. The demo also reads the first block from the attached card and displays it on the terminal.

Shown is the BOOSTXL-SHARP128 display and micro SD card reader connected to the CC3200 Launchpad.

Writing to SD card block is disabled by default using a macro defined in the main.c file, this is to avoid accidental corruption of card Filesystem.

Source Files briefly explained

main.c - Includes the main and DriverLib wrapper functions to initialize, read and write the attached card.
pinmux.c - Generated by Pinmux utility to mux out the SD Host controller signal to chip boundary.
uart_if.c - Implements the UART terminal.
startup_*.c - Initialize vector table and IDE related functions

Connect the boards

The BOOSTXL-SHARP128 is recommended for use with the CC3200 in this demo. THe BOOSTXL-SHARP128 is a boosterpack with a micro SD card interface in addition to the Sharp LCD. More information on the BOOSTXL-SHARP128 can be found here: https://www.ti.com/tool/boostxl-sharp128
However, the BOOSTXL-SHARP128 cannot be mounted directly onto the CC3200 through the Launchpad connectors. Instead, the needed signals from the SD card need to be wired directly to the appropriate pins on the CC3200.

Required wiring

CC3200 Pin	BOOSTXL-SHARP128 Pin
3V3	3V3
GND	GND
5V	5V
P07	SPI_CLK
P08	SPI_MOSI
P06	SPI_MISO

Ensure that wire lengths are kept to a minimum, especially for the SPI_CLK signal.

Usage

Setup a serial communication application. Open a serial terminal on a PC with the following settings:
- Port: Enumerated COM port
- Baud rate: 115200
- Data: 8 bit
- Parity: None
- Stop: 1 bit
- Flow control: None
Run the reference application.
- Open the project in CCS/IAR. Build the application and debug to load to the device, or flash the binary using UniFlash.

Limitations/Known Issues

For many SD cards, pull up resistors are required on the bidirectional signal lines: DAT0 and CMD.