Content originally posted in LPCWare by xiaobobo2008 on Sun Mar 17 21:02:17 MST 2013
在触摸屏驱动中的程序
static void readAndFilter(int32_t *x, int32_t* y, int32_t* z)
{
int32_t ix, iy, iz1, iz2 = 0;
int32_t lastx, lasty, lastz1, lastz2 = 0;
int i = 0;
*x = 0;
*y = 0;
*z = 0;
lasty = getFilteredValue(READ_X(0)); //READ_Y(0)交换 X Y
lasty >>= 3;
if (lasty >= 4095) {
lasty = 0;
}
_DBG("\r\n lasty data is:");_DBD32(lasty);
lastx = getFilteredValue(READ_Y(0)); //READ_X(0)
lastx >>= 3;
if (lastx >= 4095) {
lastx = 0;
}
_DBG("\r\n lastx data is:");_DBD32(lastx);
lastz1 = getFilteredValue(READ_Z1(0));
lastz1 >>= 3;
_DBG("\r\n lastz1 data is:");_DBD32(lastz1);
lastz2 = getFilteredValue(READ_Z2(0));
lastz2 >>= 3;
_DBG("\r\n lastz2 data is:");_DBD32(lastz2);
if (lastx && lastz1)
{
*z = (lastx * ABS(lastz2 - lastz1)) / lastz1;
}
else
{
*z = 0;
}
if (*z > 10500) {
*z = 0;
}
if (*z == 0) {
return;
}
for (i = 0; i < DEBOUNCE_MAX; i++) {
iy = getFilteredValue(READ_X(0)); // //READ_Y(0)交换 X Y
iy >>= 3;
if (ABS (lasty - iy) <= DEBOUNCE_TOL) {
break;
}
lasty = iy;
}
for (i = 0; i < DEBOUNCE_MAX; i++) {
ix = getFilteredValue(READ_Y(0)); //READ_X(0)交换 X Y
ix >>= 3;
if (ix > 4095) {
ix = 0;
}
if (ABS (lastx - ix) <= DEBOUNCE_TOL) {
break;
}
lastx = ix;
}
for (i = 0; i < DEBOUNCE_MAX; i++) {
iz1 = getFilteredValue(READ_Z1(0));
iz1 >>= 3;
if (ABS (lastz1 - iz1) <= DEBOUNCE_TOL) {
break;
}
lastz1 = iz1;
}
for (i = 0; i < DEBOUNCE_MAX; i++) {
iz2 = getFilteredValue(READ_Z2(0));
iz2 >>= 3;
if (ABS (lastz2 - iz2) <= DEBOUNCE_TOL) {
break;
}
lastz2 = iz2;
}
*x = ix;
*y = iy;
if (ix && iz1) {
*z = (ix * ABS(iz2 - iz1)) / iz1;
}
else {
*z = 0;
}
if (*z > 10500) {
*z = 0;
}
}
其中以下代码是什么原理啊，
if (lastx && lastz1)
{
*z = (lastx * ABS(lastz2 - lastz1)) / lastz1;
}
else
{
*z = 0;
}
if (*z > 10500) {
*z = 0;
}
