trying to program a custom arduino board, effectively an uno w 328P chip that plays some audio, with a particular board/bootloader, but having some issues. The wiring is fine, as mentioned below it will program with some board/bootloader combos, but not the one I want.
The board programs over ISP no problem (both bootloading and actual code), but I would like to be able to program via an FDTI232 board for convenience. I've connected the FDTI232 to TX/RX/power and DTR to 0.1uF cap which has other leg connected to the reset on ATMEGA328P. So, this works fine - I can write/read serial data fine, and if I load the ATMEGA with minicore bootloader it will happily program via the FDTI.
However, the minicore bootloader doesn't work with my main program - it induces massive audio noise. Furthermore, my main program uses extensive libraries that only work with arduino 1.8.1, and also with arduino AVR boards 1.6.20. More recent boards just create massive issues in the running of the code with extensive resets, noise and instability.
How can I get the board to program via FTDI in this circumstance? I gather there is an old/new bootloader that if I had the newest version of arduino might help but I am unable to update for the aforementioned reasons.
I've tried changing the board defintion uno.upload.speed to 57600 as thought it might be related to this - however I am actually wondering if this upload speed doesn't actually change the bootloader - is this correct and if so how can I change it/what else should I do?
For reference - the standard arduino 1.8.1 arduino uno bootloader works perfectly with my board - but I want to be able to bootload this onto it then upload code via FDTI.
Thanks very much for your help