83 lines
2.2 KiB
Arduino
83 lines
2.2 KiB
Arduino
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//This example shows how to draw directly to I2S with no frame buffer. It only allows low computation times per pixels
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//to be able to serve I2S fast enough
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//You need to connect a VGA screen cable and an external DAC (simple R2R does the job) to the pins specified below.
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//cc by-sa 4.0 license
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//bitluni
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#include <ESP32Lib.h>
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#include <math.h>
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//pin configuration
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const int redPins[] = {2, 4, 12, 13, 14};
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const int greenPins[] = {15, 16, 17, 18, 19};
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const int bluePins[] = {21, 22, 23, 27};
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const int hsyncPin = 32;
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const int vsyncPin = 33;
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//color palette
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unsigned long rainbow[256];
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long frameNumber = 0;
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//Our own VGA Device
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class MyVGA : public VGA14BitI
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{
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protected:
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//override frame buffer allocation
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virtual Color **allocateFrameBuffer()
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{
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return 0;
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}
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//override the sync callback to count the frames
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virtual void vSync()
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{
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frameNumber++;
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}
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//draw each line
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void interruptPixelLine(int y, unsigned long *pixels, unsigned long syncBits)
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{
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for (int x = 0; x < mode.hRes / 2; x++)
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{
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//writing two pixels improves speed drastically (avoids memory reads)
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pixels[x] = syncBits | rainbow[(x - y + frameNumber) & 255];
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}
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}
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};
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//get an instance
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MyVGA vga;
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//initial setup
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void setup()
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{
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//color palette calculations
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const float cb[][3] = {{1, 0, 0}, {1, 1, 0}, {0, 1, 0}, {0, 1, 1}, {0, 0, 1}, {1, 0, 1}};
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for (int i = 0; i < 256; i++)
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{
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//interpolate the colors from the cb array and calculate the R5G5B5 color
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float s = 6.f / 256 * i;
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int n = int(s);
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float f = s - n;
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float fi = (1 - f);
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const float *cf = cb[n];
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const float *cfn = cb[(n + 1) % 6];
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int r = int((fi * cf[0] * 0b11111) + (f * cfn[0] * 0b11111));
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int g = int((fi * cf[1] * 0b11111) + (f * cfn[1] * 0b11111));
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int b = int((fi * cf[2] * 0b1111) + (f * cfn[2] * 0b1111));
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int c = r | (g << 5) | (b << 10);
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rainbow[i] = c;
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}
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//prepare writing two pixels at once (we shift the palette by a pixel)
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for (int i = 0; i < 256; i++)
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rainbow[i] |= rainbow[(i - 1) & 255] << 16;
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//initializing the vga with a high mode where a frambuffer would never fit into the memory
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vga.init(vga.MODE500x480, redPins, greenPins, bluePins, hsyncPin, vsyncPin);
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}
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//idle, everything is happening in the interrupt
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void loop()
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{
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delay(10);
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}
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