[jnwatson]

I think a "low level function for an embedded device" is probably the riskiest well-defined software problem you might ever run into.

It isn't unlike tying your contract to the behavior of a poorly documented remote API provided by another company that won't respond to any of your requests.

The risks include: the hardware being flaky. The hardware being undocumented. The hardware having no run control. The function relying on another piece of hardware or environment not provided.

I once spent two weeks looking for a single bit not-so-helpfully labelled "WinCE" in Texas Instruments' documentation.

[flyinglizard]

I totally see where you're coming from - in my mind I had something like a modern ARM microcontroller (STM32 and the likes) where the functionality is 99% internal to the chip. For example, adding an SD card or CANBUS interface to a project - not too much you depend on the customer for in that regard.

But then again I'm at this very moment doing a board bringup for a Tegra AGX system and I wouldn't advise anyone on doing that on a fixed price contract!