@AC8GY, @KD9JCD, @DH1AKF: I will try to answer your questions below:
Sorry for my late reply!
Teensy Convolution SDR & T3.6:
* I am afraid I ruined the T3.6 support in one of my last additions to the software
* that is also the reason for the memory overflow
* the new wideband FM demodulation procedure is too heavy for the T3.6, so probably it should be commented out for the T3.6
* I am not sure when/if I will be able to repair that . . . sorry Wolfgang ! (it was not intended, my fault)
That all means: FOR THE MOMENT, the current software obviously only supports T4.0 and T4.1
CMSIS lib:
* for T4.0 or T4.1, there is no need to do anything with the library, Teensyduino already has a newer version of CMSIS included and it works without altering that lib
* for T3.6, there is the need to install a newer version and the mentioned post by Canoe is the right hint to do this
SPI speed ILI9341:
* I do not have extensive experience with different displays, but it seems that displays of different brand and sizes react differently to SPI speed, so this seems a matter of trial and error to alter the SPI speed
Heat production of T4 processor:
* my recommendation is using a heatsink: I use one with a heavy copper base and copper blades on it attached to the processor with thermal glue. This keeps the processor temperature below 45 degrees Celsius even at full speed.
* but I also speed down the processor to 300MHz often if possible in order to lower power supply drain (processor speed is a menu entry in T4.x)
* overclocking (above 600MHz) is not recommended, the software becomes unreliable and often crashes above 600MHz
Expansion to TRX:
* yes, please!
* go ahead!
* why not share your plans on this forum?
@Henk: please contact the Msi001 specialists for details of the software addressing the Msi001 (Esteban and tisho).