When you connect 2 OTG systems with a micro-USB cable, host must be micro-USB type AB and device must be micro-USB type B, isn't it ?
I don't understand why phone connectors are micro-USB type B and not micro-USB type AB : someone know why ?
A phone can be connected to a PC : it would be normal that phone connector is micro-USB type B because VBUS is powered by PC.
... But a phone can be connected to a phone : it is why, it would be more logic that phone connector is micro-USB type AB.
Problem is when I check a phone, I see micro-USB connector is type B and not type AB. With micro-USB type B connector, you can't use micro-USB type A cable and with micro-USB type AB connector, you can use all micro-USB cable type : why phone manufacturers doesn't use micro-USB type AB connector to be compatible with all cable type ? I think there is a reason, isn't it ?
I must develop a USB OTG product (not a phone) and I would to know if I must use micro-USB type AB or type B.