I am considering to run an Arduino pro mini attached to the GPIO of a Raspberry Pi.
The Arduino IDE is installed and the connection of the Arduino pro mini over TX-RX of the GPIO, seen as /dev/ttyAMA0 is operational.
But I still need to push the reset button to reprogramm the Arduino. I need it to run/be reprogrammed remote.
I am considering wiring the DTR pin of the Arduino Pro Mini to a GPIO pin and would like to find a way to generate the DTR signal like it is done during USB programming.
Has someone already done it and be so kind to explain what helps to do the job?
I don't have any experience with direct serial uploads via a Raspberry Pi so I can't help you with your question.
I have done some work on using the Raspberry Pi as an ISP programmer to upload to the Arduino board via Sketch > Upload Using Programmer. In case that's something you're interested in, I have documented my findings here:
There is also a "linuxgpio" ISP programmer option in addition to the "linuxspi" programmer option I used. I believe that is the same, except less efficient due to bit banging the SPI.