Representative Line: We All Register This

Today's maybe more of a "representative data sheet entry" than anything else.

Every developer has the experience of reading the documentation. If you've been at this for some time, you've probably read bad documentation. Documentation that is incomplete, inaccurate, or otherwise flawed. Or, my personal favorite, the brief time where Oracle tried to put all of its documentation into an Adobe Flex site (aka, a Flash application, not a real web app). That one had fun bonus features, like "breaking copy and paste" and "preventing you from deep linking to a piece of the documentation".

But software documentation has got nothing on bad data sheets. When you buy an integrated chip from a vendor, whether it's a microcontroller that'll run your code, a sensor you're trying to get data from, you're at the mercy of the datasheet for understanding how it works. Sometimes, even finding an English language datasheet can be a challenge. The more complex the chip you're trying to interact with, the more complex the datasheet needs to be, and at a certain point, a lot of vendors say, "meh, you'll figure it out." I've had chips where the datasheet and reality disagreed about what registers were available, which often means that core functions of the chip require twiddling undocumented registers. For more fun, they sometimes lie about which pins on the chip do which thing, including mislabeling which pins handle power. There's nothing more fun than the tiny little "pop" of a chip dying when you throw 5V power onto a pin that's actually ground.

Now, there are some vendors, and some products, where the datasheets are pretty solid. This isn't a universal problem, but when you're working in an embedded space, "cheapest" is frequently the main criteria for picking components, and "cheapest" means "worst documented".

Which brings us to Jarek's recent experience going through a data sheet. The chip in question had a "fantastic feature" that would change how debugging worked, which was for "super users" to enable by setting a register.

3.2.4 Super User Fantastic Feature Enable Register
The Super User Fantastic Feature Enable Register allows the user to modify the behavior of the mEDBG.
Name: SUFFER
Offset:  0x0120
Reset: 0xFF

Sometimes, doing embedded work definitely feels like the SUFFER register is set.

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