Recently I bought this touchscreen for an upcoming arduino project, when I picked it out, I knew that the documentation would probably be ok at best, as is typical with these brands of unknown reputation, but when I found myself having to piece together how to use the thing based on amazon reviews, I decided that I needed to leave myself some documentation about the dang thing. Especially since our AI ovloards were remarkably unhelpful.
Important Specs
- Working Voltage – 5v, I have tried hooking it up to the 3.3v pin, and it seemed like it was working
- Touch Screen Driver – FT6336U (up to 2 touches at a time)
- Screen Driver – ST7796U
- The product listing claims IPS, the back of the product says TFT
- Micro SD card slot
When working with a screen like this it is important to understand that the display and touch capabilities are separate. If you live in app land, like iOS/Android, you write code where you put buttons on a screen, and you add events for your touch interactions. Its actually very similar. You can’t just draw a button and expect touches to magically work. And likewise you can make it so touches are triggering buttons without actually drawing them.
With that in mind, you have to hook up to pins to control the various features separately.
And each topic could use its own article as they can be quite in depth.
Pinout
As mentioned above, the board has the pinout for the different components on it. Each of the different components can be connected to and controlled independently
| Pin | |
|---|---|
| SD_CS | SD chip select, active low |
| CTP_INT | Capacitive Touch Panel Interrupt This must be wired to an interrupt pin on the arduino if using interrupts instead of polling |
| CTP_SDA | Capacitive Touch Panel IIC bus data signal |
| CTP_RST | Capacitive Touch Panel Reset. low resets (connect to 5v for normal operation) |
| CTP_SCL | Capacitive Touch Panel IIC Bus clock signal |
| SDO(MISO) | SPI bus read data signal |
| LED | Ground to turn off screen backlight. floating leaves it on |
| SCK | SPI bus clock signal |
| SDI(MOSI) | SPI bus write data signal |
| LCD_RS | LCD command/data selection chip select high data, low command |
| LCD_RST | LCD reset, low reset (connect to 5v for normal operation) |
| LCD_CS | LCD chip select, low active |
| GND | ground |
| VCC | 5v recommended 3.3v works, but with dimmer backlight |
SPI bus is shared between the SD and LCD. the SD chip select selects between them