The list of improvements compared to the Turing Pi2 v2.4:

Improved internal USB connections:
- The Mini PCIe USB interface (used, for example, by some WiFi cards and modems) is now connected to the USB1 interface - this change allows Turing RK1 and Nvidia Jetson modules to utilize the USB interface in the Mini PCIe slot and was required to improve the node flashing experience in Node 1 and Node 2 (occasional inability to flash the modules in Node 1 and rarely in Node 2); This change affects Raspberry Pi CM4 which only contains a single USB interface (USB0) - RPi CM4 will no longer be able to use Mini PCIe modules that communicate using USB
- Added internal USB hub connected to USB0 interfaces of all nodes - this change will expose all the modules set into flashing mode to the BMC or the USB_OTG port, which means an ability to flash multiple modules at once and improves USB signal integrity
- Replaced USB-A connector for the USB_OTG function (node module flashing) with USB-C connector - will let flash the modules using USB A-to-C or USB C-to-C cables - USB A-to-A cable is no longer needed
- Added USB-A connector connected to the USB2 interface (USB0 interface for Raspberry Pi CM4 module while in USB host mode) of Node 1 - lets you connect USB keyboard and mouse (and other peripherals) to Node 1, useful, for example, while using Node 1 in a desktop mode with an HDMI screen connected
Added onboard USB-UART converter for the BMC - lets you connect to the BMC's UART using a USB-C cable (you no longer need an external USB-UART converter); Applies only to the BMC UART, node UARTs remain accessible via UART headers
Added new 8-pin connector exposing I²C and 4 GPIO pins as well as 3V3 and GND - the main purpose for this header is to connect an I²C screen and 4 buttons (a relevant product will be released later), but it can also be used for other purposes
Added an ability for the nodes to stay powered on when the BMC restarts
Replaced soldered Mini PCIe and M.2 studs with removable counterparts - improves compatibility with full-size Mini PCIe modules as well as 2260 and double-sided M.2 drives (6x M2 screws will also be included with the board - one for each M.2 and Mini PCIe slot)
Improved HDMI screen compatibility - adds higher-resolution screen support (especially noticeable for 4K screens connected to the Nvidia Jetson modules)
Improved SATA compatibility in Node 3 - helps with operating systems that could not previously boot on the modules placed in Node 3 due to unconnected #clkreq signal (mostly a case with Talos running on Raspberry Pi CM4)
Added case PWM header controlled by the BMC
Doubled the BMC flash capacity from 128 MB to 256 MB - to be used to extend the user space (can also be used to store more firmware versions)
Added FEL Mode button - makes it easier to recover from unsuccessful firmware upgrade
Added switch for toggling the embedded network switch mode between managed and unmanaged
Improved node power delivery for better efficiency - slightly reduces power consumption and generated heat, the changes will also prevent the whispering noise that could be heard on some of the boards with modules powered on
Improved the GPIO header compatibility - changed pin 17 function from GND to 3.3V to match other implementations
The RTC battery fix is integrated with the board and the RTC Battery Adapter Board is no longer needed

Changelog

Turing PI V2.5 Changelog