February 12, 2026
CTR2-Flex/CTR2-Dial firmware release v2.04.01

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This zip file contains the CTR2-Flex.bin firmware. It is used to flash the CTR2-Flex/CTR2-Dial firmware on to CTR2-Uno, CTR2-Duo, CTR2-Quad, and the older CTR2-Dial and CTR2-Flex hardware. 

Windows and Mac users can use ESPConnect, a browser based flash download tool. The CTR2-Flex and CTR2-Dial manuals have been updated with information on using this new tool.

The CTR2-Flex_install.sh file is a script that you can use to install the firmware on your M5Dial based CTR2 controller without the need of the EspressIF Flash Download tool. This file is most useful on Linux and Mac PC. 

>>> If you use the script file remember to make it an executable file. <<<

To download these files to your device, extract them into a folder then use the instructions in Appendix A: Install or Update CTR2-Flex Firmware section in the CTR2-Flex or CTR2-Dial Firmware Manuals. 

NOTE
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This version contains both CTR2-Flex and CTR2-Dial firmware, therefore, operation manuals for both firmwares are included in this zip file. There are separate hardware manuals for CTR2-Uno, CTR2-Duo, and CTR2-Quad. The CTR2-Uno and CTR2-Duo manuals can be used with older single and dual-knob CTR2-Dial and CTR2-Flex hardware.
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73, Lynn, KU7Q