I am trying to use an USB port on a development board that doesn't provide a standard A socket. Instead, it provides 4 pins: 3.3V, two data pins and ground. Looking at the datasheet of the SoC, there is a pin AVDD33_USB described as "USB analog power", which provides 3.3v instead of the expected 5v. So, I assumed the board designer simply exposed the 4 pins from the SoC directly, and that is why I measured 3.3v instead of 5. Looking through the dataseet, I found a section called "Typical Application", with the following diagram:
So, it seems I can't use the USB port directly, and I need this "charge pump" thing. So, questions:
- What is the simplest way I can use the USB port? Can a powered USB hub be directly connected to the board pins?
- What is a charge pump?
- Do I need an external 5v source?
- Is this the typical way USB controllers are exposed in SoC?
- Where does the AVDD33_USB pin enters in this diagram? If not used, why does it exists?
The SoC is a Hi3516A. The development board is called HI3516ASDI V1.0.