Char 数组的问题，如何正确构造和显示它们

Question

对于我正在共同设计的产品，我想在 LCD 屏幕上显示位图图标。受其他 this 教程的启发，我创建了一个单独的 C 文件，其中包含我要显示的图标的字节数组。

当我尝试直接显示图标时，它似乎起作用了。但是当我尝试间接地做它时——这最终将是必要的——它失败了。

真正让我感到困惑和我想了解的是；当我将垃圾图标 (CHAR ARRAY) 的数组打印到串行监视器并将其与字节数组进行比较时，它应该表示它们正确匹配。但是当我对正确显示的图像（ICON ARRAY）执行相同操作时，我打印到串行监视器的内容与它显示的字节数组不匹配，我打印的信息甚至不一致......这怎么可能?!

我已经为此苦思了一个星期了，如果能提供任何帮助，我们将不胜感激。

主文件：

// --------------------------------------------------------------------------------------
// |   This program is made for an arduino mega 2560 used in conjunction with the       |
// |           (chinese) OPEN-SMART 3.2 inch TFT LCD Shield ILI9327                     |
// | This version of the program is a slimmed down one to clearly convey the problem    |
// |           I am currenlty having drawing pictures on this setup                     |
// --------------------------------------------------------------------------------------
// This program is based on the library obtained from
// https://drive.google.com/open?id=0B6uNNXJ2z4CxYktCQlViUkI1Sms
// There is also a demo available on YouTube
// https://www.youtube.com/watch?v=JQHGYnKeC0M&t=2s

#include <Adafruit_GFX.h>    // Core graphics library
#include <MCUFRIEND_kbv.h>
MCUFRIEND_kbv tft;

// -------------------------------------------------------------------------------------
// |                            Variable declaration                                   |
// -------------------------------------------------------------------------------------

// Set colors
#define BLACK            0x0000
#define BACKGROUND       0x07FF

// No idea with this does tbh
uint16_t g_identifier;

// Spacing variables
uint8_t   cube_size = 75;
uint8_t   padding = 3;
uint8_t     ix1 = 5+2 * padding;
uint8_t     ix2 = 5+3 * padding + cube_size;
uint8_t     ix3 = 5+4 * padding + 2 * cube_size;
uint8_t     ix4 = 5+5 * padding + 3 * cube_size;
uint16_t    ix5 = 5+(6 * padding) + 4 * cube_size;
uint8_t     iy1 = 5+1 * padding;
uint8_t     iy2 = 5+3 * padding + cube_size;
uint8_t     iy3 = 5+4 * padding + 2 * cube_size;

//Progmem Icon init
extern uint8_t icon_from_progmem[];

// -------------------------------------------------------------------------------------
// |                                  Functions                                        |
// -------------------------------------------------------------------------------------
// Standard drawbitmap function

void drawBitmap(int16_t x, int16_t y,  const uint8_t bitmap[], int16_t w, int16_t h, uint16_t color) {

  int16_t byteWidth = (w + 7) / 8; // Bitmap scanline pad = whole byte
  uint8_t byte = 0;
  for (int16_t j = 0; j < h; j++, y++) {
    for (int16_t i = 0; i < w; i++) {
      if (i & 7) byte <<= 1;
      else      byte   = pgm_read_byte(&bitmap[j * byteWidth + i / 8]);
      if (byte & 0x80) tft.drawPixel(x + i, y, color);
    }
  }
}

// -------------------------------------------------------------------------------------
// |                                   Setup                                           |
// -------------------------------------------------------------------------------------
// I just copied this part to get the screen to work

void setup(void) {
  Serial.begin(9600);
  Serial.println(F("TFT LCD test"));

  //    tft.reset();                 //we can't read ID on 9341 until begin()
  g_identifier = tft.readID(); //
  Serial.print("ID = 0x");
  Serial.println(g_identifier, HEX);
  if (g_identifier == 0x00D3 || g_identifier == 0xD3D3) g_identifier = 0x9481; // write-only shield
  if (g_identifier == 0xFFFF) g_identifier = 0x9341; // serial
  //    g_identifier = 0x9329;                             // force ID


  tft.begin(g_identifier); //to enable ILI9327 driver code
  tft.setRotation(3);      //Change orientation (landscape and portrait)

}

// -----------------------------------------------------------------------------------
// |                                 Loop                                            |
// -----------------------------------------------------------------------------------

void loop(void) {
  tft.fillScreen(BACKGROUND); //

  unsigned char myCharArray[512];
  byte myChar;

  for (int k = 0; k < 512; k++) {

    // Create myCharArray from icon_from_progmem
    myChar = pgm_read_byte(icon_from_progmem + k);
    myCharArray[k] = char(myChar);

    // Print data from myCharArry to the serial monitor
    Serial.print("CHAR ARRAY: ");
    Serial.print(k);
    Serial.print("     ");
    Serial.println(myChar);
  }

  // Visual separtion string
  Serial.println("------------------------------------------------------------------");

  // Print data from icon_from_progmem to serial monitor
  for (int k=0; k<512; k++){
    Serial.print("ICONS ARRAY: ");
    Serial.print(k);
    Serial.print("     ");
    Serial.println(icon_from_progmem[k]);    
  }

  // Draw the two icons on the screen
  drawBitmap(ix2, iy1, myCharArray,       64, 64, BLACK);
  drawBitmap(ix4, iy1, icon_from_progmem, 64, 64, BLACK);

  delay(600000);

} // end of void loop

位图的单独文件：

#include <avr/pgmspace.h>

// 'PlafLamp', 64x64px
const unsigned char icon_from_progmem [] PROGMEM = {
    0x00, 0x00, 0x00, 0x01, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xc0, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x7f, 0xfe, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xc0, 0x00, 0x00, 
    0x00, 0x00, 0x0f, 0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xf8, 0x00, 0x00, 
    0x00, 0x00, 0x7f, 0xc0, 0x03, 0xfe, 0x00, 0x00, 0x00, 0x00, 0xfe, 0x00, 0x00, 0x7f, 0x00, 0x00, 
    0x00, 0x01, 0xfc, 0x00, 0x00, 0x3f, 0x80, 0x00, 0x00, 0x03, 0xf0, 0x00, 0x00, 0x0f, 0xc0, 0x00, 
    0x00, 0x07, 0xe0, 0x00, 0x00, 0x07, 0xe0, 0x00, 0x00, 0x0f, 0xc0, 0x00, 0x00, 0x03, 0xf0, 0x00, 
    0x00, 0x0f, 0x80, 0x00, 0x00, 0x01, 0xf0, 0x00, 0x00, 0x1f, 0x00, 0x00, 0x00, 0x00, 0xf8, 0x00, 
    0x00, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x78, 0x00, 0x00, 0x3e, 0x00, 0x00, 0x00, 0x00, 0x7c, 0x00, 
    0x00, 0x3c, 0x00, 0x00, 0x00, 0x00, 0x3c, 0x00, 0x00, 0x7c, 0x00, 0x00, 0x00, 0x00, 0x3e, 0x00, 
    0x00, 0x78, 0x00, 0x00, 0x00, 0x00, 0x1e, 0x00, 0x00, 0x78, 0x00, 0x00, 0x00, 0x00, 0x1e, 0x00, 
    0x00, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x1f, 0x00, 0x00, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x00, 
    0x00, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 
    0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 
    0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 
    0x00, 0x00, 0x07, 0xc0, 0x03, 0xe0, 0x00, 0x00, 0x00, 0x00, 0x03, 0xc0, 0x03, 0xc0, 0x00, 0x00, 
    0x00, 0x00, 0x03, 0xe0, 0x07, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x01, 0xf8, 0x1f, 0x80, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x3f, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xf8, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x01, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x1c, 0x00, 0x00, 0x38, 0x00, 0x00, 0x00, 0x00, 0x3e, 0x00, 0x00, 0x7c, 0x00, 0x00, 
    0x00, 0x00, 0x7e, 0x00, 0x00, 0x7e, 0x00, 0x00, 0x00, 0x00, 0xfc, 0x01, 0x80, 0x3f, 0x00, 0x00, 
    0x00, 0x01, 0xf8, 0x03, 0xc0, 0x1f, 0x80, 0x00, 0x00, 0x03, 0xf0, 0x03, 0xc0, 0x0f, 0xc0, 0x00, 
    0x00, 0x07, 0xe0, 0x03, 0xc0, 0x07, 0xe0, 0x00, 0x00, 0x07, 0xc0, 0x03, 0xc0, 0x03, 0xe0, 0x00, 
    0x00, 0x07, 0x80, 0x03, 0xc0, 0x01, 0xe0, 0x00, 0x00, 0x03, 0x00, 0x03, 0xc0, 0x00, 0xc0, 0x00, 
    0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x80, 0x00, 0x00, 0x00
};

What is displayed on the screen

左图为CHAR ARRAY，右图为ICON ARRAY。

Answer 1

在 drawBitmap() 中，您正在通过 pgm_read_byte()

遍历字节

在 avr-libc 文档中说

Read a byte from the program space with a 16-bit (near) address. Note: The address is a byte address. The address is in the program space.

作为位图副本的数组 "myCharArray" 不在程序 space 中，因此 pgm_read_byte() 无法正常运行。

Char 数组的问题，如何正确构造和显示它们

Trouble with Char arrays, how to properly construct and display them

c++

arduino

progmem