I have an ATtiny13a running code at 9.6 MHz (internal oscillator) for single pin Tx Rx half-duplex serial port at 115200 baud rate using a lib which I found online
Using FTDI 232RL or BT HC-06 in between I am able to send & receive arbitrary data between the MCU circuit and Putty/Android.
What would be the cheapest and smallest (in terms of PCB size and ATTiny memory) way to achieve the same arbitrary data communication to an Android device (non-rooted) instead of BT.
Also is there a way to achieve it keeping the MCU circuit in accessory mode for Android and NOT using Android's host mode since the MCU circuit will be powered externally and not from Android. The MCU's power source will also be delivering power to Android on the USB's Power buses.
How can I achieve arbitrary data communication between ATTiny in accessory mode and Android over USB?
Will VUSB work in this case? or do I have to buy a converter chip (CHG340?) but will that chip work in accessory mode? Also will there be any changes to support USB Type C port?