繼前幾篇實作Adafruit_GFX的圖形處理後，本篇將實作將SD卡的 BMP圖檔顯示在屏幕上，我用的是1.7吋的 TFT-LCD，因此圖檔的大小要跟顯示器的解析度一樣，否則會出現只顯示圖片的部分內容。
[材料]
- Arduino Uno x 1
- ST7735 1.7" TFT LCD顯示器 x 1
- SD Card模組 x 1
- SD Card x 1
- 麵包板 x 1
- 連接線 x n條
[接線與電路圖]
Arduino
|
LCD Pin
|
SD Card
|
3.3V
|
8 LEDA
|
-
|
Pin6
|
7 CS
|
-
|
Pin7
|
6 RS
|
-
|
Pin 5
|
5 RES
|
-
|
Pin 11
|
4 SDA
|
MOSI
|
Pin 13
|
3 SCK
|
SCK
|
Pin 10
|
-
|
CS
|
Pin 12
|
-
|
MISO
|
5V
|
2 VCC
|
VCC
|
GND
|
1 GND
|
GND
|
[程式]
// 參考來源：https://simple-circuit.com
#include <Adafruit_GFX.h>
#include <Adafruit_ST7735.h>
#include <SPI.h>
#include <SD.h>
// define ST7735 TFT display connections
#define TFT_RST 5 // reset line (optional, pass -1 if not used)
#define TFT_CS 6 // chip select line
#define TFT_DC 7 // RS/Command
#define button 2 // button pin
Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_RST);
void setup(void) {
Serial.begin(9600);
pinMode(TFT_CS, OUTPUT);
digitalWrite(TFT_CS, HIGH);
pinMode(button, INPUT_PULLUP);
// 初始設定 ST7735S TFT LCD
tft.initR(INITR_BLACKTAB);
tft.fillScreen(ST77XX_BLUE);
Serial.print("Initializing SD card...");
if (!SD.begin()) {
Serial.println("failed!");
while(1); // stay here
}
Serial.println("OK!");
File root = SD.open("/"); // 開啟SD card 根目錄
printDirectory(root, 0); // 列出所有檔案名稱跟檔案大小
root.close(); // 關閉開啟的檔案
}
void loop() {
File root = SD.open("/"); // open SD card main root
while (true) {
File entry = root.openNextFile(); // open file
if (! entry) {
// no more files
root.close();
return;
}
uint8_t nameSize = String(entry.name()).length(); // get file name size
String str1 = String(entry.name()).substring( nameSize - 4 ); // save the last 4 characters (file extension)
if ( str1.equalsIgnoreCase(".bmp") ) // if the file has '.bmp' extension
bmpDraw(entry.name(), 0, 0); // draw it
entry.close(); // close the file
delay(500);
while( digitalRead(button) ) ; // wait for button press
}
}
// 以下程式將讀取Bitmap檔案，並顯示在LCD，給予緩衝20 Pixel
#define BUFFPIXEL 20
void bmpDraw(char *filename, uint8_t x, uint16_t y) {
File bmpFile;
int bmpWidth, bmpHeight; // W+H in pixels
uint8_t bmpDepth; // Bit depth (currently must be 24)
uint32_t bmpImageoffset; // Start of image data in file
uint32_t rowSize; // Not always = bmpWidth; may have padding
uint8_t sdbuffer[3*BUFFPIXEL]; // pixel buffer (R+G+B per pixel)
uint8_t buffidx = sizeof(sdbuffer); // Current position in sdbuffer
boolean goodBmp = false; // Set to true on valid header parse
boolean flip = true; // BMP is stored bottom-to-top
int w, h, row, col;
uint8_t r, g, b;
uint32_t pos = 0, startTime = millis();
if((x >= tft.width()) || (y >= tft.height())) return;
Serial.println();
Serial.print(F("Loading image '"));
Serial.print(filename);
Serial.println('\'');
// Open requested file on SD card
if ((bmpFile = SD.open(filename)) == NULL) {
Serial.print(F("File not found"));
return;
}
// Parse BMP header
if(read16(bmpFile) == 0x4D42) { // BMP signature
Serial.print(F("File size: ")); Serial.println(read32(bmpFile));
(void)read32(bmpFile); // Read & ignore creator bytes
bmpImageoffset = read32(bmpFile); // Start of image data
Serial.print(F("Image Offset: ")); Serial.println(bmpImageoffset, DEC);
// Read DIB header
Serial.print(F("Header size: ")); Serial.println(read32(bmpFile));
bmpWidth = read32(bmpFile);
bmpHeight = read32(bmpFile);
if(read16(bmpFile) == 1) { // # planes -- must be '1'
bmpDepth = read16(bmpFile); // bits per pixel
Serial.print(F("Bit Depth: ")); Serial.println(bmpDepth);
if((bmpDepth == 24) && (read32(bmpFile) == 0)) { // 0 = uncompressed
goodBmp = true; // Supported BMP format -- proceed!
Serial.print(F("Image size: "));
Serial.print(bmpWidth);
Serial.print('x');
Serial.println(bmpHeight);
// BMP rows are padded (if needed) to 4-byte boundary
rowSize = (bmpWidth * 3 + 3) & ~3;
// If bmpHeight is negative, image is in top-down order.
// This is not canon but has been observed in the wild.
if(bmpHeight < 0) {
bmpHeight = -bmpHeight;
flip = false;
}
// Crop area to be loaded
w = bmpWidth;
h = bmpHeight;
if((x+w-1) >= tft.width()) w = tft.width() - x;
if((y+h-1) >= tft.height()) h = tft.height() - y;
// Set TFT address window to clipped image bounds
tft.startWrite();
tft.setAddrWindow(x, y, w, h);
for (row=0; row<h; row++) { // For each scanline...
if(flip) // Bitmap is stored bottom-to-top order (normal BMP)
pos = bmpImageoffset + (bmpHeight - 1 - row) * rowSize;
else // Bitmap is stored top-to-bottom
pos = bmpImageoffset + row * rowSize;
if(bmpFile.position() != pos) { // Need seek?
tft.endWrite();
bmpFile.seek(pos);
buffidx = sizeof(sdbuffer); // Force buffer reload
}
for (col=0; col<w; col++) { // For each pixel...
// Time to read more pixel data?
if (buffidx >= sizeof(sdbuffer)) { // Indeed
bmpFile.read(sdbuffer, sizeof(sdbuffer));
buffidx = 0; // Set index to beginning
tft.startWrite();
}
// Convert pixel from BMP to TFT format, push to display
b = sdbuffer[buffidx++];
g = sdbuffer[buffidx++];
r = sdbuffer[buffidx++];
tft.pushColor(tft.color565(r,g,b));
} // end pixel
} // end scanline
tft.endWrite();
Serial.print(F("Loaded in "));
Serial.print(millis() - startTime);
Serial.println(" ms");
} // end goodBmp
}
}
bmpFile.close();
if(!goodBmp) Serial.println(F("BMP format not recognized."));
}
uint16_t read16(File f) {
uint16_t result;
((uint8_t *)&result)[0] = f.read(); // LSB
((uint8_t *)&result)[1] = f.read(); // MSB
return result;
}
uint32_t read32(File f) {
uint32_t result;
((uint8_t *)&result)[0] = f.read(); // LSB
((uint8_t *)&result)[1] = f.read();
((uint8_t *)&result)[2] = f.read();
((uint8_t *)&result)[3] = f.read(); // MSB
return result;
}
void printDirectory(File dir, int numTabs) {
while (true) {
File entry = dir.openNextFile();
if (! entry) {
// no more files
break;
}
for (uint8_t i = 0; i < numTabs; i++) {
Serial.print('\t');
}
Serial.print(entry.name());
if (entry.isDirectory()) {
Serial.println("/");
printDirectory(entry, numTabs + 1);
} else {
// files have sizes, directories do not
Serial.print("\t\t");
Serial.println(entry.size(), DEC);
}
entry.close();
}
}
[實作結果]
[參考資料]
- Adafruit：Adafruit GFX Graphics Library
- Simple Projects：Draw Bitmap Images on ST7735 TFT with Arduino and SD Card
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