在ov2640参考设计中
NOTE:
1) after power on, IO pins are Input. To get image from sensor -- from default state to working state, host needs send settings to change those pins from the Input to Output.
2) IO pin status at suspend mode still depends on register ED [4] (of FF = 00), it’s either INPUT or No Change. If ED[4] is set, the IO pin will be Input when PWDN goes high, otherwise, it will keep the status of before power down.
这个被设置为0,反而没有输出。
为什么?