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You describe them as workarounds, but often this the intended design. If you only have manual control, then perhaps a driveshaft must be made larger and heavier for the case of the ham-fisted user. If the transmission is under software control, the software can be careful about accelerations to avoid overstressing the driveshaft.

The point is that when you consider the system as "mechanical, electrical and software" you get a lot more flexibility than if you think of it as "mechanical and electrical" but we do some stuff in software.

Certainly I agree the system is more complex and we could have designed it to work this way. But the stark reality was that these components were supposed to be wired a certain way in our design and the drive system was supposed to stand up to a lot more torque, as per the intended design.

So I think it is fair to call these particular fixes workarounds.

Your point that it is silly to look at these systems as anything other than integrated (often quite deeply) is well taken however. The fact that one can fix a mechanical defect using the software section of the system speaks volumes about just how integrated they are.

it always feels a bit wrong

It helps to think of it as "don't care" code rather than "error compensation" code. Which way should the engine be wired? It's cool; the software doesn't care. Just wire it up however. What order should I start these services? It's cool; they don't care. Just start them up however. As soon as your users stop caring about the stuff you can take care of, they'll have time to care about something else that's more important.

And in this case, don't forget to do a #define INVERSE_MOTOR_POLARITY 1 or similar, so that the hack is clear and doesn't bite you when porting to another platform.

It's not a bug, it's a customizable feature :)

You're in trouble though when the front motors are wired one way and the rear ones another, or one particular motor is miswired. Imagine #define FRONT_MID_SECTION_MINI_MOTOR_POLARITY (...)

Typically more like:

  #DEFINE MOTOR_0_WIRED_WRONG_BY_#$@#$_ELECTRICAL_TEAM
  #DEFINE MOTOR_1_WIRED_WRONG_BY_#$@#$_ELECTRICAL_TEAM
  ...

That said, the notion of portable embedded code when we're talking about the types of systems where these types of hacks thrive is pretty funny. These are not the type of routines people port or reuse and most of these hacks are very specific behavioral stuff to match specific pieces of hardware.

Hopefully you're not putting in hacks in the parts of the system you might actually reuse that's supposed to be more independent!

Code re-use is a principle that's often struggled outside of embedded systems. Inside embedded systems code it's downright scarce.

I think it's getting more common in the hobby community though. Just look at all the code and modules ready to use on AVRs, Stamps, etc.

It's only a shame that a lot of it is fairly unreliable C code. The situation for embedded C reminds me of PHP. You can find snippets for anything, but most of them won't be written by experienced library authors and can have an 'interesting' behaviour...

In my previous job we had several KLUDGE_TABLES as a way for our DBA to remind people that they were asking him to add a dirty hack that they promised to remove once the 'crisis' was gone. Five years later, they were still in there. At least the person querying it still had to type 'SELECT * FROM KLUDGE_…'

Well, the values actually sent out to the PWM were backwards. Thankfully I could just invert it at the last step in the code where it got sent and so while writing the actual code I could pretend everything was correct. It's hard to think of -127 going forward and 127 going backwards as anything but a dirty hack.

While the underlying electronics thankfully didn't care, the digitized values set up certain expectations.

Typically I get around this by having each motor's direction defined separately. Since you very often need to define the logic of a sensor ('1' can mean either ON or OFF depending on the sensor type) on a sensor-by-sensor basis, it makes sense to do this for motors as well.

It can get a bit mad sometimes though. The main issue is that if a hardware fault is found it is sometimes too late to rectify without a massive cost.

My management was recently trying to convince me to rewrite a FAT file system in high level code due to issues with power management, corruption and the disk we store our most precious data on.

I work in the safety critical/life-saving realm of embedded systems, and it has definitely been an eye-opener to see just how many bugs are 'forgiven' just because there is a software layer on top to make things work as expected instead of as designed ..

I just recently wrote some code to do pcb milling with pretty close tolerances. The actual milling table wasn't straight however, so when the substrate was clamped down it would have Z variations 3x larger than the desired cutting depth. A 5 minute touch probe run and a simple 2D compensation table removed the need for a time consuming tramming operations and expensive clamping hardware.

This wasn't so much fixing as augmenting. Software has the unique benefit that it can replicated essentially free while the physical improvements need to be administered separately in each and every instance.

Re. the backwards wired motors. Storing a config table in EEPROM seems to be a simple and portable solution to this. Do it in the logical way until you hit the output pins.

Do it in the logical way until you hit the output pins.

Ding, ding, ding!!! We have a winner. This is exactly correct: write your code the way everything should be in a perfect world, BUT have a hardware abstraction layer to separate that from reality. The upper layer code should just know that when the end sensor is reached, the hydraulic ram should be reversed. The HAL knows what state the end sensor must be in when it's triggered, and what polarity to send to the valve controlling the hydraulic ram.

Even in small embedded systems, a properly tiered architecture can save a lot of trouble.

Don't worry, it works the other way as well.

At my last job, I had to fix software defects in hardware.

I think I'd like to file a hug report...

Once our hardware team mounted the camera in a cell phone device upside down. Later we had to write code to rotate the image 180 degree to compensate for it.