How to compare a memory bits in C++?
- by Trunet
Hi,
I need help with a memory bit comparison function.
I bought a LED Matrix here with 4 x HT1632C chips and I'm using it on my arduino mega2560.
There're no code available for this chipset(it's not the same as HT1632) and I'm writing on my own. I have a plot function that get x,y coordinates and a color and that pixel turn on. Only this is working perfectly.
But I need more performance on my display so I tried to make a shadowRam variable that is a "copy" of my device memory. Before I plot anything on display it checks on shadowRam to see if it's really necessary to change that pixel. When I enabled this(getShadowRam) on plot function my display has some, just SOME(like 3 or 4 on entire display) ghost pixels(pixels that is not supposed to be turned on).
If I just comment the prev_color if's on my plot function it works perfectly.
Also, I'm cleaning my shadowRam array setting all matrix to zero.
variables:
#define BLACK 0
#define GREEN 1
#define RED 2
#define ORANGE 3
#define CHIP_MAX 8
byte shadowRam[63][CHIP_MAX-1] = {0};
getShadowRam function:
byte HT1632C::getShadowRam(byte x, byte y) {
byte addr, bitval, nChip;
if (x>=32) {
nChip = 3 + x/16 + (y>7?2:0);
} else {
nChip = 1 + x/16 + (y>7?2:0);
}
bitval = 8>>(y&3);
x = x % 16;
y = y % 8;
addr = (x<<1) + (y>>2);
if ((shadowRam[addr][nChip-1] & bitval) && (shadowRam[addr+32][nChip-1] & bitval)) {
return ORANGE;
} else if (shadowRam[addr][nChip-1] & bitval) {
return GREEN;
} else if (shadowRam[addr+32][nChip-1] & bitval) {
return RED;
} else {
return BLACK;
}
}
plot function:
void HT1632C::plot (int x, int y, int color)
{
if (x<0 || x>X_MAX || y<0 || y>Y_MAX)
return;
if (color != BLACK && color != GREEN && color != RED && color != ORANGE)
return;
char addr, bitval;
byte nChip;
byte prev_color = HT1632C::getShadowRam(x,y);
bitval = 8>>(y&3);
if (x>=32) {
nChip = 3 + x/16 + (y>7?2:0);
} else {
nChip = 1 + x/16 + (y>7?2:0);
}
x = x % 16;
y = y % 8;
addr = (x<<1) + (y>>2);
switch(color) {
case BLACK:
if (prev_color != BLACK) { // compare with memory to only set if pixel is other color
// clear the bit in both planes;
shadowRam[addr][nChip-1] &= ~bitval;
HT1632C::sendData(nChip, addr, shadowRam[addr][nChip-1]);
shadowRam[addr+32][nChip-1] &= ~bitval;
HT1632C::sendData(nChip, addr+32, shadowRam[addr+32][nChip-1]);
}
break;
case GREEN:
if (prev_color != GREEN) { // compare with memory to only set if pixel is other color
// set the bit in the green plane and clear the bit in the red plane;
shadowRam[addr][nChip-1] |= bitval;
HT1632C::sendData(nChip, addr, shadowRam[addr][nChip-1]);
shadowRam[addr+32][nChip-1] &= ~bitval;
HT1632C::sendData(nChip, addr+32, shadowRam[addr+32][nChip-1]);
}
break;
case RED:
if (prev_color != RED) { // compare with memory to only set if pixel is other color
// clear the bit in green plane and set the bit in the red plane;
shadowRam[addr][nChip-1] &= ~bitval;
HT1632C::sendData(nChip, addr, shadowRam[addr][nChip-1]);
shadowRam[addr+32][nChip-1] |= bitval;
HT1632C::sendData(nChip, addr+32, shadowRam[addr+32][nChip-1]);
}
break;
case ORANGE:
if (prev_color != ORANGE) { // compare with memory to only set if pixel is other color
// set the bit in both the green and red planes;
shadowRam[addr][nChip-1] |= bitval;
HT1632C::sendData(nChip, addr, shadowRam[addr][nChip-1]);
shadowRam[addr+32][nChip-1] |= bitval;
HT1632C::sendData(nChip, addr+32, shadowRam[addr+32][nChip-1]);
}
break;
}
}
If helps:
The datasheet of board I'm using. On page 7 has the memory mapping I'm using.
Also, I have a video of display working.
