DS1687_BANK1_XCTRL4A
xctl_a = ds1687_read(mace0, DS1687_BANK1_XCTRL4A);
ds1687_write(mace0, DS1687_BANK1_XCTRL4A, xctl_a);
ds1687_write(mace0, DS1687_BANK1_XCTRL4A, xctl_a | DS1687_X4A_PAB);