My bad... as I didn't remembered you talking of IRDA out before on this topic, I assumed the chip you selected didn't have IRDA and didn't check the previous page...

Thanks for the link. I think I understand now.

Wouldn't the proper way to do this be that the chip is configured with the expected 1200 bauds and modulate it after (with an ne555 like or an I2C PWM expander if its period needs to be software controlled).
This would reduce the I2C load (probably not a problem anyway), and remove the need for some bit conversions to send data, so something like "cat /dev/xxx" would allow to see directly the received value (and not a list of 0x0 or 0xF for each individual bit) ?

Your solution work, but I always tend to choose hardware when possible to avoid doing tricky stuff in software.

Edit : After second though, there may be problems with the start/stop bits with this proposal. Don't know if they are the same on IR than with say a RS232 line, so that the UART would understand them correctly ?