Is OTG a must requirement for USB DAC/Portable HD/Mouse/Keyboard etc.. to work on Android?
My Q10 Pro TV Box runs on Android 5.1 and can have access directly on my Portable HD, DAC and Mouse w/o OTG cable.
A guy in a forum says it runs on my unit's OTG implementation.
Nope! The Android device must have a USB host port in order to work with USB DAC/Portable HD/Mouse/Keyboard/etc.
USB is a master-slave communication bus: USB communication can only take place between a master device and a slave device.
A master, or USB host, is usually a computing device.
A slave, or USB peripheral, can be a USB DAC, a hard disk drive, a mouse, a keyboard, a computing device, etc.
The HiMedia Q10 Pro TV box has several USB ports:
http://www.futeko.com/products/MP068.php
. Three USB host ports:
music player running on Q10 Pro operating as USB host > Q10 Pro: USB host port >> regular USB cable >> USB DAC: USB peripheral port > USB DAC
. One USB peripheral port:
Q10 Pro operating as USB peripheral > Q10 Pro: USB peripheral port >> regular USB cable >> PC: USB host port > file explorer running on PC
The smartphone has only one USB port: it should be a dual-role USB port, sometimes a USB host port, sometimes a USB slave port.
As legacy computers, legacy peripherals like Android smartphones having all the features of a computer need to interconnect with peripherals. This slave-to-slave communication functionality is not supported by the master-to-slave communication USB model.
To address this need, the USB OTG concept is added to the USB standard in 2009.
USB OTG retains the legacy master-to-slave or USB host-to-USB peripheral communication model.
A USB OTG device is a dual-role USB device, sometimes a USB host, sometimes a USB peripheral:
. a USB OTG-capable Android device operating as a USB peripheral can interwork with a PC operating as a USB host
. a USB OTG-capable Android device operating as a USB host can interwork with a USB DAC always operating as a USB peripheral.
A USB OTG software program and USB OTG hardware components are added at the USB level. A USB OTG device is configured to USB host mode or USB peripheral mode by USB OTG software/hardware measuring the value of the ID resistance of the USB interface:
. Smartphone configured as USB host:
music player running on smartphone > smartphone: USB "host" port >> so called USB OTG cable (ID pin grounded) >> USB DAC: USB peripheral port > USB DAC
. Smartphone configured as USB peripheral:
smartphone > smartphone: USB "peripheral" port >> regular USB cable >> PC: USB host port > file explorer running on PC