January 1, 2026 Update
To simplify the CTR2 product line, CTR2-Flex hardware is being rebranded. The one and two knob hardware is exactly the same as before, but with new names. My hope is that this will make it much easier for you to decide which model is right for you.
The hardware has been named for the number of knobs it supports. One and two knob versions will continue to be available in either the commercial New Age CNC machined enclosure, or in a 3D printed enclosure that was designed by Neil, G7UFO. The new CTR2-Quad four-knob version will only be available in the 3D printed enclosure.
All CTR2 hardware based on the M5Dial from M5Stack runs CTR2-Flex firmware. This firmware can boot into either CTR2-Flex mode that connects directly to a Flex radio using WiFi and the Flex API, or CTR2-Dial MIDI mode, that uses Bluetooth or USB MIDI commands to control a 3rd-party app like Marcus’ (DL8MRE) SmartSDR for iOS/MacOS, SDR-Control, FT-Control, TS-Control, K4-Control, Thetis, SDR-Console, and many others.
New hardware branding is shown below.
CTR2-Uno, (previously known as CTR2-Flex with one knob), has a single large tuning knob. This knob can be assigned to control two of the available dial functions using a turn and push-and-turn actions. It uses a no-detent (smooth) encoder since its primary function is for VFO control. The knob has a pushbutton that can be assigned to two button functions using short and long-press actions. The unit also has a dual-purpose 3.5mm (1/8″) stereo jack that supports CW paddles or key and PTT inputs.
CTR2-Duo (previously known as CTR2-Flex with two knobs) has two small knobs. These knobs can be assigned to control up to four of the available dial functions using a turn and push-and-turn actions. Both knobs use detent (bumpy) encoders since their primary use is for volume, keyer speed, DSP level control, etc. Each knob has a pushbutton that can be assigned to two button functions using short and long-press actions. The unit also has a dual-purpose 3.5mm (1/8″) stereo jack that supports CW paddles or key and PTT inputs.
CTR2-Quad, a new product introduce in 2026, has four knobs. The three small knobs use detent (bumpy) encoders and the large knob uses a no-detent (smooth) encoder. The knob functions are the same as described above for CTR2-Uno and CTR2-Duo.
CTR2-Dial Hardware
CTR2-Dial hardware is being depreciated and will be discontinued once I run out of parts to build them. The main difference between the current hardware and the older CTR2-Dial hardware is that the older hardware does not support the CW paddle jack on the dual-knob version, and the encoders used on CTR2-Dial hardware do not have pushbuttons, so push-and-turn dial functions and knob button functions are not supported.
As always, let me know if you have any suggestions or find bugs in the firmware. I’ll do my best to resolve bugs ASAP.
Thanks for your support,
73, Lynn