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0 pointscalamari40652y ago0 comments

It's unfortunately not that simple. For most parts you can get breakout boards or dev kits that implement the chip and all its support circuitry. You can drop those into a simple PCB or just a breadboard and get going pretty quick. This is appallingly expensive for more than a handful of prototypes, but it does work. IME, this is how software people approach electronics.

The real trouble comes during the next step. You have to integrate all these disparate boards into one unit. You can copy schematics and layouts from the dev boards, but that takes a lot of time. Once you've done that, you need to re-validate your entire stack, electronics, firmware, and software. You will inevitably find that you've missed a connection or the routing introduced some noise or you got this component value wrong. So you spin a new board, wait a week, and do it all over again several more times.

Debugging electronics is a lot like debugging software. Except that the code is physical objects and the bugs are emergent properties of the whole system and are inherently chaotic. You (generally) can't step through the system like you would with code, you can only observe a small number of nodes in the system at any one time.

It's harder than you expect because you're dealing with invisible forces and effects of the fundamental laws of physics. It requires either very deep knowledge or a lot of time in iterations to solve some of these problems.

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JoeCortopassi2y ago

To expand on this, if software was like hardware:

    - when your function calls don't have enough white space between them, they'll some times mix up their return value (crosstalk)
    - the more deeply your if/else statements are nested, the more random their results end up being (voltage/IR drop)
    - when the user makes a selection, your bound function is called somewhere between once and a dozen times. Each time with a different value (bounce)
    - their is no `true` or `false`. You just are given a float between one and zero, where one is true and zero is false. Sometimes `true` is as low as 0.3 and sometimes `false` is as high as 0.7
    - the farther apart your variable declaration is from it's use, the less it represents what you actually declared. If it's two lines apart, a 'foo' string is still 'foo'. Hundred lines apart though, and 'foo' might become 5.00035 (attenuation)

calamari4065OP2y ago

If you want your program to execute as fast as possible, you have to worry about the speed of light! A trace a few millimeters longer than its partner can have nanoseconds of delay which can easily corrupt your data!

And don't forget that you have to balance the physical shape and arrangement of components and traces with frequency and surrounding components otherwise you've created a transmitter spewing out noise at tens of MHz.

Or the corollary: if you aren't careful you can receive radio signals that will corrupt your data.

Oh, you think your wire can handle the 0.5A your widget needs? Let me tell you about transients that spike to tens of amps for a few hundred nanoseconds. But it's okay, that problem can be solved with a bit of trigonometry.

On the plus side, if you forget to connect your ADC to something, you now have a surprisingly decent random number source.

I love the absolute chaotic insanity of electronics. On the surface things make sense, but one level deeper and nothing makes sense. If you go further than that, at the bottom you'll find beautiful and pure physics and everything makes sense again.

I feel the same way about software. It's a hot mess, but under everything there's this little clockwork machine that simply reads some bits, then flips some other bits based on a comparison to another set of bits. There's no magic, just pure logic. I find it a very beautiful concept.

GianFabien2y ago

Not so fast, some alpha particles from a distant galaxy strike your memory chips and some bits flip. If the CPU gets too hot or too cold it starts misinterpreting opcodes, branches, etc.

The reality is that computers are comprised of several PCBs running with thousands of multi-GHz signals. So all of the foregoing engineering design principles had to be observed to make our systems as reliable as they are.

c_o_n_v_e_x2y ago

I came here to say what you just did. Hardware modularity is incredibly useful in the face of unstable product requirements. Focusing on integration, optimizing form factor can come once the requirements are locked in (if such a condition ever exists lol).

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