I am working on a project that uses an Android or iOS app to control an Arduino. It is crucial that the tablet to Arduino connection is reliable. I've chosen to control it via a wired serial connection. I haven't tried using Bluetooth or Wifi because Google searches have lead me to believe they are unreliable. Is this still the case?
Currently, I'm not able to keep the tablet charged while it is being used to control the Arduino. Has anyone been successful in charging a tablet or iPad while it's being used to control an Arduino? Are there resources that you can point me to?
camelalchemist:
Google searches have lead me to believe they are unreliable
This is nonsense, and you are probably just reading what you want to read. Wirelees is so normal that any outfit the can't produce reliable comms would be out of business the next week. You will probably find the normalcy of wireless is reflected in the number and variety of apps using it compared with USB host. Indeed, while USB host is typical in tablets, it is not universal in phones.
Currently, I'm not able to keep the tablet charged while it is being used to control the Arduino. Has anyone been successful in charging a tablet or iPad while it's being used to control an Arduino?
I imagine practically everybody. Tablets typically use a separate socket for charging, thereby avoiding your problem. I have seen splitter cables for phone. I thought it was for audio, but I guess data ones exist.
There are apps to check USB Host capabilities.
Of the tablets I own, only one has it. 
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camelalchemist:
I am working on a project that uses an Android or iOS app to control an Arduino. It is crucial that the tablet to Arduino connection is reliable. I've chosen to control it via a wired serial connection. I haven't tried using Bluetooth or Wifi because Google searches have lead me to believe they are unreliable. Is this still the case?
Currently, I'm not able to keep the tablet charged while it is being used to control the Arduino. Has anyone been successful in charging a tablet or iPad while it's being used to control an Arduino? Are there resources that you can point me to?
Try plugging the tablet and arduino into a USB hub with its own power supply if they connect it will charge the tablet and power the Arduino.