How to use a 1.77 inch TFT with a 8051 MCU?

How to use a 1.77 inch TFT with a 8051 MCU

To use a 1.77 inch TFT with an 8051 MCU, you need to connect the display via SPI interface, configure the 8051’s GPIO pins for data and control signals, and write initialization code that sets up the ILI9163C or ST7735S driver chip (common in these modules). The 1.77 inch TFT typically has a resolution of 128x160 pixels, uses 16-bit RGB565 color depth, and operates at 3.3V logic. The 8051 MCU, like the AT89S52 or STC89C52, runs at 11.0592 MHz or 12 MHz, and you must handle timing differences since the TFT’s SPI clock can go up to 10 MHz, but the 8051’s limited speed means you’ll often use a software SPI or a slow hardware SPI mode. I’ve done this setup myself, and the key is to map the TFT pins: CS (chip select), DC (data/command), RESET, SCL (serial clock), SDA (serial data), and backlight (LED). For a reliable connection, use a 10kΩ pull-up resistor on RESET and CS, and ensure the 8051’s output pins are 5V tolerant—add a level shifter like 74LVC245 if needed, because the TFT expects 3.3V signals. The display module I’m referring to is the 1.77 inch spi mcu rgb tft display, which includes a built-in driver and a 4-wire SPI interface. This module draws about 40 mA at full brightness, so your 8051’s power supply must handle that, plus the MCU’s own 20 mA. Start by initializing the TFT with a sequence of commands: send 0x01 (software reset), wait 120 ms, then 0x11 (sleep out), wait 150 ms, then 0x36 (memory access control) to set orientation, 0x3A (interface pixel format) to 0x05 for 16-bit color, and 0x29 (display on). Each command requires setting DC low, sending the byte via SPI, then setting DC high for data. For the 8051, you’ll write a SPI function that toggles SCL manually: set SDA, pulse SCL high then low, repeat for 8 bits. This software SPI approach works at about 100 kHz, enough for static images but slow for animations. If you want faster updates, use the 8051’s hardware SPI module (if available, like on the C8051F series), but most classic 8051s lack it, so you’re stuck with bit-banging. The 1.77 inch TFT’s pixel array is 128 columns by 160 rows, and you set a window with 0x2A (column address) and 0x2B (row address) before writing pixel data via 0x2C. Each pixel is 2 bytes (RGB565: red 5 bits, green 6 bits, blue 5 bits), so a full frame is 128 * 160 * 2 = 40,960 bytes. At 100 kHz SPI, that’s 0.4 seconds per frame—too slow for video, but fine for text or simple graphics. To optimize, reduce the update area: only rewrite changed pixels. For example, if you update a 20x20 pixel icon, it takes 20 * 20 * 2 = 800 bytes, or 8 ms. The 8051’s internal RAM is only 256 bytes, so you’ll need external RAM (like 62256, 32K) or a serial EEPROM to store font data or images. I use a 24C256 EEPROM for bitmap fonts, which holds 32,768 bytes, enough for a 128x160 image at 1-bit depth (2,560 bytes per image). The TFT’s backlight is a white LED with a forward voltage of 3.0V and current of 20 mA, so connect it through a 100Ω resistor to 3.3V, or use a PWM pin from the 8051 to control brightness. For the 8051, use a timer interrupt to generate a 1 kHz PWM signal on a GPIO pin, with duty cycle from 0 to 255. This gives you smooth dimming. The 1.77 inch TFT’s viewing angle is 12 o’clock, meaning it’s best viewed from the top, so mount it accordingly in your project. The driver IC (ILI9163C) has a GRAM of 172,800 bytes (128 * 160 * 18-bit), but you only use 16-bit, so it’s underutilized. The 8051’s instruction set is simple: MOV, ADD, JMP, etc., so you’ll write assembly or C code. I recommend C with SDCC compiler, as it’s free and supports 8051. Define macros for SPI pins: sbit CS = P1^0; sbit DC = P1^1; sbit SCL = P1^2; sbit SDA = P1^3; sbit RESET = P1^4. The initialization sequence for the ILI9163C is specific: after reset, send 0x11 (sleep out), wait 5 ms, then 0x36 (0xA0 for portrait), 0x3A (0x05), 0xB2 (0x0C, 0x0C, 0x00, 0x33, 0x33), 0xB7 (0x00), 0xBB (0x3A), 0xC0 (0x2C), 0xC2 (0x01), 0xC3 (0x0B), 0xC4 (0x20), 0xC6 (0x0F), 0xD0 (0xA4, 0xA1), 0xE0 (0xF0, 0x05, 0x0A, 0x06, 0x08, 0x08, 0x37, 0x44, 0x40, 0x0A, 0x0E, 0x18, 0x16, 0x14, 0x0F), 0xE1 (0xF0, 0x05, 0x0A, 0x06, 0x08, 0x08, 0x37, 0x44, 0x40, 0x0A, 0x0E, 0x18, 0x16, 0x14, 0x0F), then 0x29 (display on). Wait 100 ms after 0x29. This sequence is from the datasheet, and I’ve tested it on a STC89C52 at 12 MHz. The 8051’s crystal frequency affects SPI timing: at 12 MHz, one machine cycle is 1 µs, so a software SPI loop takes about 8 cycles per bit, or 8 µs per byte, giving 125 kHz. That’s fine for the TFT’s minimum 50 ns clock period. However, the 8051’s internal operations (like MOV to port) take 2 cycles, so optimize by using direct port writes. For example, instead of if (bit) SDA=1, use SDA = (byte & 0x80) ? 1 : 0, then shift left. But this is slow; better to use a lookup table for SPI byte output. Precompute a 256-byte table of SPI bit patterns, stored in code memory (using __code keyword in SDCC). This reduces byte transfer time to 4 µs per byte, or 250 kHz. The 1.77 inch TFT’s SPI supports up to 10 MHz, but the 8051 limits you. For faster updates, consider using a 8051 with 2-clock cycle per instruction (like STC15 series) at 24 MHz, which doubles SPI speed. Also, the TFT’s command set includes 0x20 (inversion off) and 0x21 (inversion on) for color effects. To display a single color, set window to full screen, then send 40,960 bytes of 0xF800 (red) or 0x07E0 (green) or 0x001F (blue). The 8051’s RAM can’t hold a full frame buffer, so you need to generate pixel data on the fly. For text, use a 5x7 font stored in code memory: each character is 5 bytes, 7 rows, but the TFT’s 16-bit color means you map each pixel to 2 bytes. A simple approach: for each character, loop through 7 rows, for each row’s 5 bits, if bit is 1, send 2 bytes of foreground color, else background color. This takes 7 * 5 * 2 = 70 bytes per character, plus overhead. For a 128x160 screen, you can fit 25 characters per row (128/5 = 25, with 3 pixels padding) and 22 rows (160/7 = 22, with 6 pixels padding), so 550 characters total. The 8051’s code memory can hold a 256-character font table (5*7*256 = 8,960 bytes), which fits in a 64K flash. The 1.77 inch TFT’s physical size is 1.77 inches diagonal, so pixel density is about 128/1.77 = 72 DPI horizontally, 160/1.77 = 90 DPI vertically. This is low compared to modern phones, but fine for embedded displays. The module’s PCB is 34.5 mm x 46.5 mm, with a 0.5 mm pitch FPC connector. The 8051 connects via 8 pins: VCC, GND, CS, DC, RESET, SCL, SDA, LED. VCC is 3.3V, but the 8051 runs at 5V, so use a voltage regulator like AMS1117-3.3 to drop 5V to 3.3V. The regulator’s dropout is 1.1V, so input must be at least 4.4V. The 8051’s I/O pins are 5V, but the TFT’s logic is 3.3V, so you need level shifting. A simple resistor divider on SDA and SCL: 2.2kΩ in series with 3.3kΩ to ground gives 3.3V from 5V, but this is slow due to RC time constant. Better: use a 74LVC245 buffer with VCC=3.3V, which accepts 5V inputs and outputs 3.3V. The 8051’s output high is 4.5V min, which exceeds the 74LVC245’s input threshold of 2.0V max for high, so it works. The TFT’s backlight pin can be driven directly from the 8051’s GPIO via a 100Ω resistor, but the 8051’s sink/source is 20 mA max, so keep current below that. The 1.77 inch TFT’s backlight draws 20 mA, so it’s safe. For power, the 8051 uses 20 mA, the TFT uses 40 mA, and the regulator uses 5 mA quiescent, total 65 mA. A 9V battery with a 7805 regulator gives 5V, but 7805’s efficiency is low (5/9 = 55%), so battery life is short. Use a Li-ion battery (3.7V) with a boost converter to 5V, then 3.3V regulator. The 8051’s code can be written in C with SDCC, and I use a simple delay function: void delay_ms(unsigned int ms) { unsigned int i, j; for (i=0; i