CTR2-MIDI (I’ll call it MIDI here) is a custom MIDI controller designed for ham operators using radio control apps that support MIDI control. It works with Marcus’ iOS and MacOS apps, Remote Ham Radio, and several Windows apps like Thetis and SDR-Console. It supports both USB and Bluetooth LE (BLE) MIDI connections.
Hold the press!
Starting with v2.00.00 firmware (released November 3, 2025) CTR2-MIDI now has the ability to connect directly to your Flex radio over WiFi. Similar to CTR2-Flex (but without a display), this new mode (called Flex WiFi mode, uses the Flex Network API to control your radio. It also provides network CW keying and PTT. Because it connects to the radio, it doesn’t require a 3rd-party radio control app, and it works with any version of SmartSDR, even Windows versions.
SmartSDR for iOS/MacOS
Marcus (DL8MRE) has added support for CTR2-MIDI to all of his iOS and MacOS apps. You can use CTR2-MIDI and a conventional MIDI controller (such as DJ2GO) at the same time. Look for the CTR2 Controller icon in the Tools menu in his apps.
Remote Ham Radio
Remote Ham Radio has added beta support for CTR2-MIDI. You can access the CTR2-MIDI Configuration page under the Tools tab in the RHR – Universal Console.
NOTE: CTR2-MIDI does not work directly with wfview, piSDR, and several other radio control programs because these apps do not support MIDI controllers. Please verify the app you want to control supports either USB or Bluetooth-LE MIDI before ordering. You can use a MIDI translator program such as CoyoteMIDI for basic frequency control. Checkout this post on using MIDI control on non-MIDI enabled apps for more information on this option.
PLEASE NOTE: Marcus has been kind enough to add support for the MIDI to his apps, but he is not involved in the MIDI’s design or firmware. Please don’t waste his valuable time asking for technical support or feature upgrades to the MIDI. If you have questions please contact me.
The MIDI provides a physical tuning knob with eight functions, six dual-mode pushbuttons, and a 3.5mm (1/8″) jack so you can use your paddles, a straight key, or a PTT switch with the app.
v2.00.00 brings a new Extended Button mode option. This mode allows you to map up to 48 button functions (12 on each knob mode) and is available in the classic MIDI control mode or the new Flex WiFi mode.
CTR2-MIDI’s are in stock and I can ship the next day after payment. Please visit my new online Shop to order your unit.
SmartLink Support
SmartSDR for iOS supports SmartLink so there is no need to forward ports or use VPNs to connect to a remote radio. Just connect your MIDI to your iOS device and you have the perfect remote operation setup.
NOTE: The new Flex WiFi mode does not support SmartLink. It works great when the radio is on the same LAN. When you want to operate remotely, just switch the mode back to classic MIDI mode and use SmartSDR for iOS/MacOS to access SmartLink.
Powering Options
The MIDI is powered through it’s USB-C connection. It can be powered by an older iOS device (with a Lightning connector) using an OTG adapter as shown below. It can be powered directly from a new iOS device (with the USB-C connector), from a computer’s USB port, a cell phone charger, or a USB battery pack. A small 5000 mAH battery powers it for over 12 hours. It can connect to the iOS or Mac device using BLE so no physical connection is required when it’s not plugged directly into the device.
Unlike CTR2-Micro, in classic MIDI mode the MIDI has no internal radio control logic. The entire radio user interface (UI) is handled by the app. The MIDI only sends MIDI commands, it doesn’t monitor any of the settings in the app. Mapping the MIDI’s controls to the app is the only setup required.
When used in the new Flex WiFi mode, the MIDI is aware of the radio’s state and it monitors changes in the radio made on SmartSDR.
I’ve added a video on CTR2-MIDI to my YouTube channel. You can view it here.
Extended Button Mode in v2 Firmware
v2.00.00 firmware brings the ability to control up to 48 button functions in your radio control app. You can learn more about this new mode in this video.
But I already have a CTR2-Micro
If the only reason you bought the Micro is for remote Flex control you may be a little frustrated with needing to forward your radio’s control port through your router or manage a VPN so you can access your radio remotely. Many Flex users operate remote radios provided by clubs or friends what won’t allow port forwarding or VPNs on their network (and for good reason).
I have created a version of CTR2-MIDI firmware that runs on the ESP32-C3 processor in the Micro. You can download this firmware to convert your Micro into a MIDI, a “Micro-MIDI” if you will. The difference between the two hardware platforms is that while the MIDI has six buttons and four status LEDs the Micro only has three buttons, one status LED, and does not support USB MIDI. The differences between the two are spelled out in the CTR2-MIDI Operation Manual. One of the nice things about this solution is that you can always reflash the Micro with Micro firmware to return it to normal operations.
Mike, WB6DJI, has also posted a YouTube video on his remote operation of W6HA. He’s using his CTR2-Micro running CTR2-MIDI firmware.
I hope you find this new addition the the CTR2 product line useful. As always, if you have any questions or suggestions, please contact me. My email address is good on QRZ.com.
73, Lynn, KU7Q