COM8_AEC
com8 &= ~COM8_AEC;
ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AEC);
com8 |= COM8_AEC;
com8 &= ~COM8_AEC;
{ REG_COM8, COM8_FASTAEC|COM8_AECSTEP|COM8_BFILT|COM8_AGC|COM8_AEC },
{ REG_COM8, COM8_FASTAEC|COM8_AECSTEP|COM8_BFILT|COM8_AGC|COM8_AEC|COM8_AWB },
reg |= (COM8_AEC | COM8_AGC);
reg &= ~(COM8_AEC | COM8_AGC);