How to implement UART messaging at 0.6 baud?

Question

linux

On a QNX device, in the sysinit file, in the port initialization line, I changed the speed to 250000 bod, as a result, instead of 250000 bod, the system began to transfer bytes in 5 seconds. (Bit time ~560 milliseconds). Of course, no arduino / avr / stm32 library supports such a speed by default, and there are no more communication channels with the device.
How to implement data exchange on arduino / avr / stm32 controllers or on PC at speeds less than 1 baud? Maybe there are some special libraries?

Answer 1

If you want to do something, do it yourself)
Posted the project on github.
Arduino-STM32-software-UART-with-a-float-baudrate.

Answer 2

take a software uart
var2: read the dock on the hardware module (there is a variant that may lack the capabilities of a frequency divider) and configure it bypassing the standard drivers.

Answer 3

And it doesn't suit you? wikihandbk.com/wiki/Arduino:%D0%9F%D1%80%D0%B8%D0%...