Post a Contest

Sharing the power lines of different USB ports together

Status: Closed
Prize: $10
Entries Received: 1
Winner: kzkg778

Winner

Contest Brief

During the design of a custom PCB (picture 1) for a private proof-of-concept project, there have arised several questions. This contest aims to get the best solution for the questions below.

========================
Description:
========================

(1) the board will be using 3 UART ports of a microcontroller, each connected to a UART-to-USB converter (picture 2) and a fourth USB port designed only for supplying power (it may sometimes be connected to a power bank but often will be left unconnected)

(2) this board will not have an own fix power source, so it will have to be powered by any of the devices (phone, computer...) connected to any of its USB ports (the power bank may not always be available)

(3) any combination of devices connected in USB 1, 2 or 3 will send and receive data from and to the board

(4) in case there's a phone + computer or a phone + power bank connected, I would like to have the phone charged, provided that there's still enough source to drain

========================
What has to be solved:
========================

(1) can I connect the UART-to-USB converters' +5 V together (and the GND together) to power up the circuits on the board? Remember that a power source can not be always attached, therefore I have to get power from wherever it is available (usb1, 2, 3 or 4)

(2) should I use a protection circuit to protect each USB port from peaks on the +5 V line coming from the other ones? which chip? how to connect it?

(3) what would the correct connections and circuits to use between the USB connectors and the UART ports?

(4) Important: the solution must provide ***a jpg diagram *** showing the chips to be used and the routings to be done, with the list of chips from Aliexpress. Chip modules are required as I cannot order discrete components, and these chips must not be SMD, because I am going to solder them by hand (I am not that good!)

Thanks to all in advance for your proposals...