I set the fuses of my attiny85 so it uses the internal 128khz clock, prescaled so it is 16kHz. I set the CKOUT fuse too so I can check the clock using an oscilloscope on pin 3 and yes it is 16kHz.
Now my problem is I have no option in the Arduino IDE to compile my code for 16kHz clock speed. The slowest I have is 128khz, which causes the "blink" sketch to run for 8 seconds up, 8 seconds low on my attiny instead of 1 second.
I tried with "attiny" from David A. Mellis using https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json (Slowest : 1Mhz) and "ATTinyCore" from Spence Konde using http://drazzy.com/package_drazzy.com_index.json (Slowest : 128khz).
Does someone know how I can set my Arduino IDE to compile the code for an attiny85 using the 16khz internal clock ?
(Please, no question "why use a 16khz clock ?". The point is, this chip may be set to 16khz clock, so it should be possible to program it to use such clock speed)