Is there any chance to reduce the startup time of the UNI R4 Minima
I measured a startup time of about 500ms from getting the supply voltage till my code gets executed
I read something about deleting the bootloader ? But after some research i think its only possible with an UNO R3? Or am i wrong with this assumption?
In general when you program via the ISP connections no bootloader is loaded. Program starts nearly immediately.
Caution, to revert to bootloader in the future you will have to find a bootloader code and program it via ISP.
yes but i dont know how to remove the bootloader from an arduino uno r4 minima...
got 2 R4 minimas and one R3 minima for programming.. is there any chance?
Exactly what boards have you got ?
You don't have to remove the bootloader. When you program via ISP the program overwrites the bootloader.
It sounds like we are getting into semantics here. Every reprogrammable µP I've ever seen can be programmed in circuit. I am not familiar with the Renesas RA Family however I'm confident there is a way to program the device in circuit, certainly not the same as for the AVR or other Microchip processors, but doable none the less.
Just out of interest: what kind of solution are you building where 500ms startup time needs to be reduced?
Most (add-on) hardware requires at least this or even more time to ensure a proper power-on-reset is happening so it has a solid starting point. Even life-saving-equipment would not have a demand of 0.5 seconds power-on-reset.
@Delta_G , @UKHeliBob
i got 2 Arduino Uno R4 Minima
and one Arduino Uno R3
I thought i can use the R3 to programm the R4
@Delta_G
Do you have any further instructions for programming via RFP?
This seems to be the most promising solution atm
one more question
how can i check if i really deleted the bootloader?
One way of telling if you have removed the bootloader is trying to upload new code using the bootloader. You won't be able to do so.
Also your program will start up quicker - your original objective.
... if it starts at all...
Removing the bootloader is it simple to brick the board, i think
i think the first steps are done now 
but my code isnt running... i guess if i flash the hex-file created out of my ino-file with "export compiled binary" all the libarys are not included or am i wrong?
You are wrong, the libraries included in the code during linking process after the compiling, the compiled binary is a full firmware, including all libraries and source.
okay.. strange thing...
maybe i did something wrong then.. cause even the RFP cant get a connection to the board now
damn ^^