[Weixue RP2040 dual-core development board] Artistic dial generation + pitfall avoidance guide

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[Weixue RP2040 dual-core development board] Artistic dial generation + pitfall avoidance guide [Copy link]

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Preface

In the previous article, we introduced the construction of the C development environment and used the official Demo to experience the LCD display.

We can see that the circular LCD has a good display effect. When you see a circular LCD, you will definitely think of the dial.

In this article, we will generate some artistic watch faces.

process

Using the C example project,

Add draw.c and draw.h files

draw.c

#include "LCD_1in28.h"

#include <math.h>

#include <stdint.h>

#define DIM 240

#define DM1 (DIM-1)

#define _sq(x) ((x)*(x)) // square88ikkkkkkkkkkkkkkkkkk

#define _cb(x) abs((x)*(x)*(x)) // absolute value of cube

#define _cr(x) (unsigned char)(pow((x),1.0/3.0)) // cube root

void draw_test1(void)

{

unsigned char RD1(int i,int j){

return (char)(_sq(cos(atan2(j-DIM/2,i-DIM/2)/2))*255);

}

unsigned char GR1(int i,int j){

return (char)(_sq(cos(atan2(j-DIM/2,i-DIM/2)/2-2*acos(-1)/3))*255);

}

unsigned char BL1(int i,int j){

return (char)(_sq(cos(atan2(j-DIM/2,i-DIM/2)/2+2*acos(-1)/3))*255);

}

uint8_t r;

uint8_t g;

uint8_t b;

for(volatile int j=0;j<DIM;j++)

{

for(volatile int i=0;i<DIM;i++)

{

r = RD1(i,j)&255;

g = GR1(i,j)&255;

b = BL1(i,j)&255;

LCD_1IN28_DisplayPoint(i, j, (((uint16_t)r>>3)<<11) | (((uint16_t)g>>2)<<5) | (((uint16_t)b>>3)<<0));

}

}

}

void draw_test2(void)

{

unsigned char RD2(int i,int j){

static double k;k+=rand()/1./RAND_MAX;int l=k;l%=DIM/2;return l>255?DIM/2-1-l:l;

}

unsigned char GR2(int i,int j){

static double k;k+=rand()/1./RAND_MAX;int l=k;l%=DIM/2;return l>255?DIM/2-1-l:l;

}

unsigned char BL2(int i,int j){

static double k;k+=rand()/1./RAND_MAX;int l=k;l%=DIM/2;return l>255?DIM/2-1-l:l;

}

uint8_t r;

uint8_t g;

uint8_t b;

for(volatile int j=0;j<DIM;j++)

{

for(volatile int i=0;i<DIM;i++)

{

r = RD2(i,j)&255;

g = GR2(i,j)&255;

b = BL2(i,j)&255;

LCD_1IN28_DisplayPoint(i, j, ((r>>3)<<11) | ((g>>2)<<5) | ((b>>3)<<0));

}

}

}

void draw_test(void)

{

draw_test1();

DEV_Delay_ms(2000);

draw_test2();

DEV_Delay_ms(2000);

}

draw.h

#ifndef DRAW_H

#define DRAW_H

void draw_test(void);

#endif

Call the test function in c/examples/LCD_1in28_test.c

intLCD_1in28_test(void)

{

if(DEV_Module_Init() != 0)

{

return-1;

}

adc_init();

adc_gpio_init(29);

adc_select_input(3);

LCD_1IN28_Init(HORIZONTAL);

LCD_1IN28_Clear(WHITE);

DEV_SET_PWM(60);

while(1)

{

draw_test();

}

DEV_Module_Exit();

return0;

}

Compile

cd to RP2040-LCD-1.28/c/build path

export PICO_SDK_PATH="/home/lhj/pico-setup/pico/pico-sdk" && cmake ..

make

The generated program is located in the current path

Copy it to Windows, download it to the development board and run it

cp main.uf2 /mnt/d

test

Avoid pitfalls

Write function can not be displayed

voidLCD_1IN28_DisplayPoint(UWORDX, UWORDY, UWORDColor)

{

LCD_1IN28_SetWindows(X,Y,X,Y);

LCD_1IN28_SendData_16Bit(Color);

}

Xend and Yend are both -1

void LCD_1IN28_SetWindows(UWORD Xstart, UWORD Ystart, UWORD Xend, UWORD Yend)

{

//set the X coordinates

LCD_1IN28_SendCommand(0x2A);

LCD_1IN28_SendData_8Bit(0x00);

LCD_1IN28_SendData_8Bit(Xstart);

LCD_1IN28_SendData_8Bit((Xend-1)>>8);

LCD_1IN28_SendData_8Bit(Xend-1);

//set the Y coordinates

LCD_1IN28_SendCommand(0x2B);

LCD_1IN28_SendData_8Bit(0x00);

LCD_1IN28_SendData_8Bit(Ystart);

LCD_1IN28_SendData_8Bit((Xend-1)>>8);

LCD_1IN28_SendData_8Bit(Yend-1);

LCD_1IN28_SendCommand(0X2C);

}

So change it to

voidLCD_1IN28_DisplayPoint(UWORDX, UWORDY, UWORDColor)

{

LCD_1IN28_SetWindows(X,Y,X+1,Y+1);

LCD_1IN28_SendData_16Bit(Color);

}

The screen cannot be displayed

for(intj=0;j<DIM;j++)

{

for(inti=0;i<DIM;i++)

{

r = RD2(i,j)&255;

g= GR2(i,j)&255;

b= BL2(i,j)&255;

LCD_1IN28_DisplayPoint(i, j, ((r>>3)<<11) | ((g>>2)<<5) | ((b>>3)<<0));

}

}

Change to

for(volatileintj=0;j<DIM;j++)

{

for(volatileinti=0;i<DIM;i++)

{

r = RD2(i,j)&255;

g= GR2(i,j)&255;

b= BL2(i,j)&255;

LCD_1IN28_DisplayPoint(i, j, ((r>>3)<<11) | ((g>>2)<<5) | ((b>>3)<<0));

}

}

The compiler is too smart and optimizes the double loop, although it should not be optimized away from any perspective (i.e., it is not multi-threaded access to global variables, nor is it the use of global variables in callback functions).

So this is also where the compiler may be self-defeating. Personally, I think this should be considered a compiler bug, because there is no reason to optimize it away no matter how high the compilation level is set.

Summarize

1. In order to see the process of generating the above image, the calculation is done point by point and then drawn, so there is a screen refresh process. In actual application, it needs to be written to the buffer first and then refreshed.
2. Artistic images are generated by formulas, which are actually color displays of function graphs. You can find some interesting generating functions by yourself.
3. There is a bug in the demo code.
4. Nested loop write points may be optimized and require volatile modifier variables to avoid optimization.

lugl4313820

The refresh is a bit slow.

qinyunti

lugl4313820 posted on 2022-12-5 09:15 The refresh is a bit slow to keep up.

As explained in the text, the calculation is done intentionally to display one bit per bit, in order to demonstrate the drawing process.

In fact, it must be written to the buffer first and then refreshed again.