I need to connect the TFT Display WF18FTLLAADNN0# (ST7735S) to the Arduino using SPI, but the documentation says that when connected, pin D/C (pin32) is combined with SPI_SCL. Has anyone connected this display to an Arduino?
I found the answer, the model WF18FTLLAADNN0# has only a 3-wire SPI interface (SDA,SCL,CS pins), in my case I need a 4-wire one (SDA,SCL,CS,DC pins) . This is the WF18GTLLAADNN0# model.
The SPI bus has a 3 lines - MISO, MOSI and SCK. What is the "4 wire SPI" ?
Sorry, but here is a complete confusion in your head. These pin names - SDA,SCL,CS,DC - has nothing to do with SPI interface. The names of the signals SDA and SCL refer to I2C bus. And there are no such thing as "4-wire SPI".
But in fact, these names mean little. In Chinese datasheets, the signal designations are often confused. You can try to connect the display to the Arduino SPI using as follow:
TFT SPI_SCL - Arduino SPI_SCK
TFT SPI_SDA - Arduino SPI_MOSI
TFT SPI_CS - Arduino CS
Just keep in mind that this display does not support 5v logic level, so you must use an arduino with signal level 3v3 or a level converter
This is a common name used with TFT and e-paper displays that don't have SDO (for MISO).
It is for proper SPI signals SCK and MOSI, with DC and CS added for display controller signals.
3-wire SPI is used for the case where DC is embedded with data, a.k.a. 9-bit SPI.
I2C usually don't use CS, as the destination addressing is part of the protocol.
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