CTR2-Max offers a larger display, more knobs and pushbuttons, and better sidetone when operating in Flex mode with AetherSDR’s CTR2 Relay.
This firmware runs on the CTR2-Max-5 unit.
Download the latest firmware here.
October 28, 2026 – v2.00.01
- Fixed a bug that was causing intermittent lockups when connected to AetherSDR’s CTR2 Relay
- Fixed a bug that blocked the knobs from working in the PTT page
- Fixed a bug that blocked the buttons for CW Macros 5 to 9 from working
- Added the Battery icon back in. The internal battery is useful when operating with a battery operated device such an iPhone or iPad. It powers Max without draining the device’s battery.
- Added additional time to the latching PTT timeout timer
Download the Firmware
Download the latest firmware using the link below. The zip file ships with the firmware manuals for both Flex WiFi and MIDI mode. It also includes the hardware manuals for CTR2-Max-5.
Once you have installed v2.00.00 you will be able to update the CTR2-Max firmware from within the CTR2 Relay panel in AetherSDR. Go to Settings->Controllers->CTR2… to find CTR2 Relay.
NOTE: There is only one BIN file, named CTR2-Max_v2.0x.xx.bin. Extract this file to a folder on your PC.
Flashing the Firmware
AetherSDR users can use the new CTR2-Max Update Firmware feature in the CTR2 Relay panel to upload new firmware to their unit after they have upgraded to CTR2-Max v2.00.00. Just download the zip file above to a folder on your computer, then in the Lynovation tab in CTR2 Relay, click the Open File… button to select the zip file and the Install… button to flash the new firmware. More about this feature can be found here.
If you don’t run AetherSDR, I highly recommend using ESPConnect with a Chrome, Opera, or Edge browser to flash this firmware because you usually don’t need to force the ESP32-S3 processor into Boot mode.
NOTE: ESPConnect does not run on Linux.
NOTE: The ESP32-S3 operates in TinyUSB Serial mode, and this mode will be listed in ESPConnect when you first connect to your unit. When you try to connect to TinyUSB, the connection will fail. Just click the Connect button again in ESPConnect. On the second try, your unit will be listed as a USB JTAG/serial debug unit device on a different serial port. You should be able to connect to this device.
Leave the Flash Offset set to 0x0.
NOTE: If ESPConnect can’t force your unit into programming mode (USB JTAG) automatically, you’ll need to use a small screwdriver to press and hold the Boot button on the back of the unit while you cycle power (or use another small screwdriver to press and release the Reset button on other side of the USB-C connector.)
Once you are connected to the unit, click on Flash Tools in the left menu, then scroll down to the Flash Firmware text box. Click on this box then navigate to the folder you unzipped CTR2-Max.bin and select it.
Do not select the “Erase entire flash before writing” checkbox. This will erase the entire flash memory, including your configuration files, registration key, and AetherCTR2 if it has been installed.
Click the Flash Firmware button to start the flash process. Once it complete, cycle the power on your unit and verify that the firmware version matches the version listed here.
Revision History
October 24, 2026 – v2.00.00
- This is a major program update that removes WiFi and Bluetooth modes (due to FCC restrictions) and adds support for AetherSDR’s new CTR2 Relay feature in v26.10.3 and above. The relay provides a USB connection for CTR2-Max’s Flex mode that replaces the Flex WiFi mode. It also includes support for the new AetherCTR2 app that was created by the AetherSDR development team. This app can be used in place of the stock CTR2-Max app in Flex mode. You can read more about these updates here.
October 5, 2026 – v1.01.03a
- This is the last version of CTR2-Max that supports WiFi and Bluetooth.
- This version fixes a bug I unknowingly injected into v1.01.01 that erased the map name in MIDI mode.
- v1.01.03a has a minor fix to allow Auto Connect to work properly
September 29, 2026 – v1.01.03
- Removed RADE mode that was added in v2.05.04. Not supported by Flex API so it can’t be controlled remotely
- Added an UNKN radio mode label – for when the radio sends a mode CTR2-Flex doesn’t understand
- Ignore “transmit frequency” from API for dial control – it shows the repeater offset frequency in TX mode and cause erratic tuning behavior
September 28, 2026 – v1.01.01
- Fixed RTTY mode bug that was causing erratic tuning when in RTTY mode
- Added support for NFM and RADE modes, including default filters
- Added panadapter Auto-Center toggle to Panadapter1 dashboard page – when enabled, tuning can appear choppy as panadapter redraws for every tune step
- Improved transverter detection so extended bands are shown when transverter is enabled on RxAnt or TxAnt
- Added “&” character to character list – for users that have a & in their router password
September 14, 2026 – v1.01.00
- Replaced the Knobs menu with the new Controls menu. This menu provides a graphical view of the knob and switch/pushbutton functions and allows you to easily change the functions assigned to each control.
August 16, 2026 – v1.00.02
- This version fixes several bugs in the MIDI mode firmware in the initial product release, v1.00.01. If you’re running v1.00.01, you should re-flash your unit with this firmware.
- No substantial changes were made in the Flex WiFi mode firmware.
August 3, 2026 – v1.00.01
- Initial product release firmware