An Android app to remotely control a Zoom H2n digital audio recorder via bluetooth.
The recorder has a socket for a wired remote control - a 2.5mm TRRS jack. Control is by means of a 2400 baud serial connection and the corresponding plug wired:
- Tip: RX
- Next Ring: TX
- Next Ring: Ground
- Sleeve: 3.3V power (out)
TX, RX and Ground can be connected to a readily-available serial Bluetooth module, such as the HC-06, though as these modules require 5V power, an additional power supply will be required. There are 3.3V Bluetooth modules, but the Zoom does not seem to have the capacity to power them.
The HC-06 will need to be configured for the correct baud rate (at least) and for this purpose it will have to be connected to a serial port with 3.3V logic levels . It can either be programmed by using AT commands, or more simply by using this convenient utility.
(More details of the harware to be provided)
The Android app is written in C# (for reasons that will be explained elsewhere) and requires Visual Studio 2019 with the Xamarin extensions for Android if you want to tinker with it. Unfortunately, this requires a huge amount of disk space.
You will also, obviously, need an Android device running at least Android 5.1 and sufficient screen estate for the buttons.
An apk file can be downloaded from the repository (in the apk directory) - it's not available in the Play store. Further instructions on sideloading can be found here.
Once the HC-06 is correctly configured and wired to the Zoom recorder, you will need to pair it with the Android device from the Bluetooth menu.
Use the "scan..." button in the app to select the correct Bluetooth device. It will only show devices that are already paired and support Bluetooth serial communications. Your choice will be remembered and used the next time the app is launched.
Initially the buttons will be dimmed and disabled, but when the app has successfully connected to the recorder, the applicable buttons will be highlighted and enabled. Different buttons are available in Play mode and Record mode.
More information on my blog.
- Tim Dixon
This project is licensed under the MIT License - see the LICENSE.md file for details
Various people have details online of their efforts to decode the protocol used by the wired remote controls and other projects to build hardware or software controllers. Some of those who have been most helpful include: