Previously – an overview of the particular screen I’m using
In this post I’m going over the SD card functionality
For this, I will be using an arduino mega compatible device. But any arduino with SPI should work just fine.
SPI and CS
SPI is the Serial Peripheral Interface. SPI is similar to IIC but it requires chip select lines for each device, and has differences in the speed, and the actual protocol. But just like IIC, it allows multiple devices to communicate a lot of information without the need to use a lot of GPIO pins
The CS pins are chip select, and they tell a device whether it is the selected device on the bus, so it knows which signals to pay attention to, which to ignore, and when it has a turn to respond on the bus
The SD card reader uses SPI so wiring is as simple as wiring up the SPI wires, and the SD card’s chip select.
If the only thing we were interested in using was the SD card, then we could wire SD_CS directly to ground, but wiring it to a GPIO pin allows us to have more devices on the SPI bus.
This is true whether we’re using the SD card on the TFT screen, or a stand alone SD card module
Code
From here, the code is actually quite simple. We can use the SD library by Arduino and SparkFun, and run one of their examples
I used CardInfo to verify the wiring, and that communication with my SD card is working