- Name: ST7735
- Description:
C++ Raspberry pi PICO library for a TFT SPI LCD, ST7735 Driver
There are example files included. User picks the one they want by editing the CMakeLists.txt :: add_executable(${PROJECT_NAME} section. Comment in one path and one path only.
| Filename | Function | Note |
|---|---|---|
| hello | Hello world | --- |
| text | Text + fonts | --- |
| graphics | Graphics | --- |
| functions_fps | Functions(like rotate, scroll) + FPS tests | --- |
| bmp_data | 1,8 & 16 bit bitmaps tests + bitmap FPS tests | Bitmap data is stored in arrays on PICO |
| demos | A demo showing a gauge | --- |
| frame_buffer | Testing frame Buffer mode | dislib16_ADVANCED_SCREEN_BUFFER_ENABLE must be enabled user option 2 |
In the main.cpp example files. There are four sections in "Setup()" function where user can make adjustments to select for SPI type used, PCB type used and screen size.
- USER OPTION 0 SPI_SPEED + TYPE
- USER OPTION 1 GPIO
- USER OPTION 2 SCREEN SECTION
- USER OPTION 3 PCB_TYPE
USER OPTION 0 SPI SPEED
Here the user can pass the SPI Bus freq in kiloHertz, Currently set to 8 Mhz. Max SPI speed on the PICO is 62.5Mhz. There is a file with SPI test results for the FPS tests in extra/doc folder. 2nd parameter is the SPI interface(spi0 spi1 etc).
If users wants software SPI just call this method with just one argument for the optional GPIO software uS delay, which by default is zero. Setting this higher can be used to slow down Software SPI which may be beneficial in some setups.
USER OPTION 1 GPIO
The 5 GPIO pins used, the clock and data lines must be the clock and data lines of spi interface chosen in option 0 if using hardware SPI.
USER OPTION 2 Screen size + Offsets
In the main.cpp file, in USER OPTION 2 . User can adjust screen pixel height, screen pixel width and x & y screen offsets. These offsets can be used in the event of screen damage or manufacturing errors around edge such as cropped data or defective pixels. The function TFTInitScreenSize sets them.
USER OPTION 3 PCB Version
Select your PCB controller type by passing an enum type to function TFTInitPCBType. Default is "TFT_ST7735R_Red". If you select the wrong one if may still work but with inverted colors.
| Number | Description | Enum label | Tested on |
|---|---|---|---|
| 1 | ST7735B controller | TFT_ST7735B | n/a |
| 2 | ST7735R "Green Tab" | TFT_ST7735R_Green | n/a |
| 3 | ST7735R "Red Tab" | TFT_ST7735R_Red | RED PCB v1.1, 1.44 , 128 x 128 pixels |
| 4 | ST7735S "Black Tab" | TFT_ST7735S_Black | RED PCB v1.2, 1.8 , 128 x 160 pixels |
Functions to support drawing bitmaps & sprites.
| Num | Function Name | Colour support | bitmap size Max | Note |
|---|---|---|---|---|
| 1 | drawBitmap | bi-colour | 2048 bytes | Data horizontally addressed |
| 2 | drawBitmap8Data | 8 bit color RRRGGGBB | 16384 | Data from array on PICO, Converted by software to 16-bit color |
| 3 | drawBitmap16Data | 16 bit color 565 | 32768 | Data from array on PICO |
| 4 | drawSpriteData | 16 bit color 565 | 32768 | Data from array on PICO, Draws background color transparent |
- Bitmap size in kiloBytes = (screenWidth * screenHeight * bitsPerPixel)/(1024 * 8)
- Math in bitmap size column 1-4 assumes 128x128 pixel screen.
- The data array for 1 is created from image files using file data conversion tool link
- The data array for 2-4 is created from BMP files using file data conversion tool link
Connections as setup in main.cpp test file.
| TFT PinNum | Pindesc | HW SPI |
|---|---|---|
| 1 | LED | VCC |
| 2 | SCLK | GPIO18 |
| 3 | SDA | GPIO19 |
| 4 | A0/DC | GPIO3 |
| 5 | RESET | GPIO4 |
| 6 | SS/CS | GPIO2 |
| 7 | GND | GND |
| 8 | VCC | VCC |
- NOTE connect LED backlight pin 1 thru a 150R/220R ohm resistor to 3.3/5V VCC.
- This is a 3.3V logic device do NOT connect the I/O logic lines to 5V logic device.
- You can connect VCC to 5V if there is a 3.3 volt regulator on back of TFT module.
- SW SPI pick any GPIO you like , HW SPI SCLK and SDA will be tied to spio interface.
- Backlight on/off control is left to user.
