Interfacing PIC16F887 with ST7735 TFT display
The ST7735 needs a driver which can be found in the topic below:
ST7735 SPI TFT Display Driver for CCS PIC C compiler
After downloading the driver file just put it on the project folder.
The ST7735 uses SPI communication protocol and the PIC16F887 has one SPI module.
Generally the SPI protocol uses 3 lines: SCK (serial clock), SDI (serial data in) and SDO (serial data out) but for interfacing the ST7735 TFT we use only 2 lines: SCK and SDO.
The PIC16F887 has one SPI module with SCK mapped to RC3 pin (#18) and SDO mapped to RC5 (#24).
Components Required:
- PIC16F887 microcontroller
- ST7735 1.8" TFT display
- 20MHz crystal oscillator
- 2 x 22pF ceramic capacitor
- 5 x 1Kohm resistors
- Protoboard
- 5V Power supply source
- Jumper wires
Example circuit diagram is shown below.
In this project I used 20MHz crystal oscillator which is the PIC16F887 maximum speed for highest SPI data transfer rate (5Mbit/s). Lower crystal frequencies can be used or even the internal oscillator of the microcontroller.
5 x 1K ohm resistors are needed because basically the ST7735 works with 3.3V and the PIC16F887 works with 5V , it may be damaged if it connected directly to the microcontroller. The TFT is supplied with +5V because its board contains AMS1117 3.3V voltage regulator.
Interfacing PIC16F887 with ST7735 TFT display CCS C code:
The code has been tested with CCS PIC C compiler version 5.051.
ST7735 TFT driver is needed to compile the code.
/* PIC16F887 with ST7735 TFT display example CCS PIC C code ST7735 TFT display driver for CCS PIC C compiler is required Coordinates are (x, y) starting from upper left corner (0, 0) http://ccspicc.blogspot.com/ electronnote@gmail.com */ // TFT module connections #define TFT_CS PIN_D0 #define TFT_DC PIN_D1 #define TFT_SPI_HARDWARE // End TFT module connections #include <16F887.h> #fuses NOMCLR NOBROWNOUT NOLVP HS #use delay(clock = 20MHz) #include <ST7735_TFT.c> int8 k = 0; char *txt = "1.8 Inch ST7735 TFT display test example"; void testlines(unsigned int16 color) { unsigned int8 x, y; fillScreen(ST7735_BLACK); for (x=0; x < _width; x+=6) { drawLine(0, 0, x, _height-1, color); } for (y=0; y < _height; y+=6) { drawLine(0, 0, _width-1, y, color); } fillScreen(ST7735_BLACK); for (x=0; x < _width; x+=6) { drawLine(_width-1, 0, x, _height-1, color); } for (y=0; y < _height; y+=6) { drawLine(_width-1, 0, 0, y, color); } fillScreen(ST7735_BLACK); for (x=0; x < _width; x+=6) { drawLine(0, _height-1, x, 0, color); } for (y=0; y < _height; y+=6) { drawLine(0, _height-1, _width-1, y, color); } fillScreen(ST7735_BLACK); for (x=0; x < _width; x+=6) { drawLine(_width-1, _height-1, x, 0, color); } for (y=0; y < _height; y+=6) { drawLine(_width-1, _height-1, 0, y, color); } } void testfastlines(unsigned int16 color1, unsigned int16 color2) { int16 x, y; fillScreen(ST7735_BLACK); for (y = 0; y < _height; y += 5) { drawFastHLine(0, y, _width, color1); } for (x = 0; x < _width; x += 5) { drawFastVLine(x, 0, _height, color2); } } void testdrawrects(unsigned int16 color) { int16 x; fillScreen(ST7735_BLACK); for (x = 0; x < _width; x+=6) { drawRect(_width/2 -x/2, _height/2 -x/2 , x, x, color); } } void testfillrects(unsigned int16 color1, unsigned int16 color2) { int16 x; fillScreen(ST7735_BLACK); for (x = _width - 1; x > 6; x -= 6) { fillRect(_width/2 -x/2, _height/2 -x/2 , x, x, color1); drawRect(_width/2 -x/2, _height/2 -x/2 , x, x, color2); } } void testfillcircles(unsigned int8 radius, unsigned int16 color) { int16 x, y; for (x = radius; x < _width; x += radius * 2) { for (y = radius; y < _height; y += radius * 2) { fillCircle(x, y, radius, color); } } } void testdrawcircles(unsigned int8 radius, unsigned int16 color) { int16 x, y; for (x = 0; x < _width + radius; x += radius * 2) { for (y = 0; y < _height + radius; y += radius * 2) { drawCircle(x, y, radius, color); } } } void testroundrects() { int8 i, t; unsigned int16 color = 100; fillScreen(ST7735_BLACK); for(t = 0 ; t <= 4; t += 1) { unsigned int8 x = 0, y = 0, w = _width - 2, h = _height - 2; for(i = 0 ; i <= 16; i++) { drawRoundRect(x, y, w, h, 5, color); x += 2; y += 3; w -= 4; h -= 6; color += 1100; } color += 100; } } void testtriangles() { unsigned int8 t, w, x, y, z; unsigned int16 color = 0xF800; fillScreen(ST7735_BLACK); w = _width/2, x = _height - 1, y = 0, z = _width; for(t = 0 ; t <= 15; t++) { drawTriangle(w, y, y, x, z, x, color); x -= 4; y += 4; z -= 4; color += 100; } } void mediabuttons() { // play fillScreen(ST7735_BLACK); fillRoundRect(25, 10, 78, 60, 8, ST7735_WHITE); fillTriangle(42, 20, 42, 60, 90, 40, ST7735_RED); delay_ms(500); // pause fillRoundRect(25, 90, 78, 60, 8, ST7735_WHITE); fillRoundRect(39, 98, 20, 45, 5, ST7735_GREEN); fillRoundRect(69, 98, 20, 45, 5, ST7735_GREEN); delay_ms(500); // play color fillTriangle(42, 20, 42, 60, 90, 40, ST7735_BLUE); delay_ms(50); // pause color fillRoundRect(39, 98, 20, 45, 5, ST7735_RED); fillRoundRect(69, 98, 20, 45, 5, ST7735_RED); // play color fillTriangle(42, 20, 42, 60, 90, 40, ST7735_GREEN); } void main(){ TFT_BlackTab_Initialize(); fillScreen(ST7735_BLACK); drawtext(0, 5, txt, ST7735_WHITE, ST7735_BLACK, 1); setTextWrap(false); strcpy (txt, "Hello World!"); drawtext(0, 30, txt, ST7735_RED, ST7735_BLACK, 1); drawtext(0, 47, txt, ST7735_YELLOW, ST7735_BLACK, 2); drawtext(0, 80, txt, ST7735_MAGENTA, ST7735_BLACK, 3); drawtext(0, 120, txt, ST7735_CYAN, ST7735_BLACK, 4); delay_ms(5000); fillScreen(ST7735_BLACK); drawFastHLine(0, 53, _width, ST7735_WHITE); drawFastHLine(0, 106, _width, ST7735_WHITE); while(k++ < 20){ sprintf(txt,"%02u",k); drawtext(59, 25, txt, ST7735_GREEN, ST7735_BLACK, 1); drawtext(54, 75, txt, ST7735_BLUE, ST7735_BLACK, 2); drawtext(49, 125, txt, ST7735_RED, ST7735_BLACK, 3); delay_ms(500); } testlines(ST7735_YELLOW); delay_ms(1000); testfastlines(ST7735_RED, ST7735_BLUE); delay_ms(1000); testdrawrects(ST7735_GREEN); delay_ms(1000); testfillrects(ST7735_YELLOW, ST7735_MAGENTA); delay_ms(1000); fillScreen(ST7735_BLACK); testfillcircles(10, ST7735_BLUE); testdrawcircles(10, ST7735_WHITE); delay_ms(1000); testroundrects(); delay_ms(1000); testtriangles(); delay_ms(1000); mediabuttons(); delay_ms(1000); while(TRUE){ invertDisplay(true); delay_ms(500); invertDisplay(false); delay_ms(500); } }Finally the following video shows the ST7735 and PIC16F887 in a protoboard circuit:
