5 ms·

Bingo. Additionally, control theory block diagrams are pretty rigorous, with algebraic rules for manipulating them you'll find in a controls textbook. You can

Bingo. Additionally, control theory block diagrams are pretty rigorous, with algebraic rules for manipulating them you'll find in a controls textbook. You can pretty much enter a block diagram from Apollo documentation into Simulink and "run" it, in much the same way you could run a spice simulation on a schematic from that era.

tonyarkles 2y ago
Yeah, there's a really interesting phenomenon that I've observed that goes with that. If what you're describing was the main way people used it, I'd be very satisfied with that and have actually been chewing on ways to potentially bring those kinds of concepts into the more "mainstream" programming world (I'm not going to go way off on that tangent right now) What I've seen many times though in my career that awkwardly spans EE and CS is that people forget that you can still... write equations instead of doing everything in Simulink. As an example I was looking at a simplified model of an aircraft a couple months ago. One of the things it needed to compute was the density of air at a given altitude. This is a somewhat complicated equation that is a function of altitude, temperature (which can be modelled as a function of altitude), and some other stuff. These are, despite being a bit complicated, straightforward equations. The person who had made this model didn't write the equations, though, they instead made a Simulink sub-model for it with a bunch of addition, multiplication, and division blocks in a ratsnest. I think the Simulink approach should be used when it brings clarity to the problem, and should be abandoned when it obscures the problem. In this case it took a ton of mental energy to reassemble all of the blocks back into a simple closed-form equation and then further re-arranging to verify that it matched the textbook equation.
- buescher 2y ago
  I had an intern do something similar with an electromechanical machine. I'd all but written the equations out for him but he found drawing it out in Simulink in the most fundamental, primitive blocks to help him understand what was going on . I don't get it either. A related phenomenon seems to be people who don't want to "wire up" schematics but attach named nets to every component and then draw boxes around them.
  - tonyarkles 2y ago
    > people who don't want to "wire up" schematics but attach named nets to every component and then draw boxes around them Lol there are a few things that I am highly intolerant of and this is one of them. The only place where I'm generally ok with that approach is at the input connectors, the microcontroller, and the output connectors. Same philosophy as I said before though: "if it brings clarity draw it as a wired up schematic; if it turns into a ratsnest use net labels to jump somewhere else". Having every component in a separate box with net labels will generally obscure what's going on and just turns it into an easter egg hunt.
    - buescher 2y ago
      Also, part of the style seems to be to contort any actual schematic to fit in the box. I like to ask "if you wouldn't put it on its own page so you could draw it clearly, why did you draw a box around it?".
    - foldr 2y ago
      I don't really get this point of view. Take an I2C bus, for example. Isn't it easier to read the schematic if all the components on the bus have two pins connected to wires labeled 'SDA' and 'SCL'?
      - tonyarkles 2y ago
        Yeah, there’s a balance here. There are common nets like SDA, SCL, GND, VCC that make sense to have as global nets. And then there’s actual circuits where it makes more sense (for understandability) to not do it like that. Here’s an example that I think takes it too far: https://cdn.sparkfun.com/datasheets/Dev/LilyPad/LilyPad-MP3-v15a.pdf https://cdn.sparkfun.com/datasheets/Dev/LilyPad/LilyPad-MP3-... - The audio jack (line level) could have just sat to the right of the codec and been directly connected to it to make it clear that it’s just a direct output - the speaker amplifier could be directly connected to the audio jack as well. I spent a lot of time looking around to figure out where it actually connects to; I figured it would have its input connected to the MP3 codec and didn’t realize that it would be connected through the micro switches inside the headphone jack (which makes sense now that I see it) - the SD card slot could either be connected directly to the codec or could have better names on the nets. When I see MOSI, MISO, and SCK I assume that they’re connected to the main MCU. Even more confusing, there’s an SD-CS that is connected to the MCU but not the rest of the SPI pins Overall I’d probably give this one a B. It’s by no means the most egregious I’ve seen but it also obscures the signal flow pretty badly. Other things I would probably consider doing: - better clustering of pins on the MCU by function. The switch inputs and LED outputs that connect to the rotary encoder are all over the place. Most tools allow you to move the pins on microcontrollers around at will - the FTDI block could move onto the first page. The DTR pin could use a bit of explanation that it’s tied to the reset circuit. Not their fault in this one but the naming inconsistency between FTDI-RXI and TRIG4/TXO is confusing until you figure out that the pin is meant to be either a GPIO or a UART pin. The name doesn’t make it clear that it goes to the FTDI chip because it’s inconsistent with the rest of the FTDI-xxx names but that’s because most ECAD programs handle net names poorly anyway Edit: one more thing that really bugs me about this schematic: the Vbatt net leaving J1. It’s labelled but not with any kind of flag or loose/unterminated line that would indicate that it’s connected to the net leaving U2. And further with that, the fact that VIN on U2 comes only from the FTDI connector on the second page (I think…)
- mighmi 2y ago
  Where can I read about your project or hear your tangent?
  - tonyarkles 2y ago
    I'm hoping at a minimum get my thoughts written out while I'm flying this weekend! The quick gist is that Jupyter is frustrating for me because it's so easy to end up in a situation where you inadvertently end up with a cell higher up in your document that is using a value computed in a cell further down. It's all just one global namespace. In the Julia world with Pluto they get around this by restricting what can go into cells a little bit (e.g. you have to do some gymnastics if you're going to try to assign more than one variable in a single cell); by doing it this way they can do much better dependency analysis and determine a valid ordering of your cells. It's just fine to move a bunch of calculation code to the end/appendix of your document and use the values higher up. The idea I've been chewing on comes somewhat from using Obsidian and their whole infinite canvas idea. It seems like using ideas from Pluto around dependency analysis and being able to also determine whether the contents of a given cell are pure or not (i.e. whether they do IO or other syscalls, or will provide outputs that are solely a function of their inputs) should be able to make it easier to do something... notebook-like that benefits from cached computations while also having arbitrary computation graphs and kind of an infinite canvas of data analysis. Thinking like a circuit simulator, it should be possible to connect a "scope" onto the lines between cells to easily make plots on the fly to visualize what's happening. Anyway, that's the quick brain dump. It's not well-formed at all yet. And honestly I would be delighted if someone reads this and steals the idea and builds it themselves so that I can just an off-the-shelf tool that doesn't frustrate me as much as Jupyter does :)
    - sterlind 2y ago
      it sounds like the ideal solution would be something functional (so you have a computation graph), pure (so you can cache results) and lazy (so order of expressions doesn't matter.) why not Haskell? or even a pure/lazy subset/variant of Julia, if you want to ditch the baggage of Haskell's type bondage? you could ditch explicit cells entirely, and implement your "scope" by selecting a (sub)expression and spying on the inputs/outputs.
- singleshot_ 2y ago
  One cool thing about, for instance, density altitude calculations or runway length calculations, is that you can break the parts of the algorithm down graphically do pilots can trace through datapoints to get an answer without even having a calculator. See many pilot operating handbooks for examples.
  - bandrami 2y ago
    Also works for power/moment data on marine freight, in fact I used to have a job at a shipyard drawing those.

tonyarkles 2y ago

Yeah, there's a really interesting phenomenon that I've observed that goes with that. If what you're describing was the main way people used it, I'd be very satisfied with that and have actually been chewing on ways to potentially bring those kinds of concepts into the more "mainstream" programming world (I'm not going to go way off on that tangent right now) What I've seen many times though in my career that awkwardly spans EE and CS is that people forget that you can still... write equations instead of doing everything in Simulink. As an example I was looking at a simplified model of an aircraft a couple months ago. One of the things it needed to compute was the density of air at a given altitude. This is a somewhat complicated equation that is a function of altitude, temperature (which can be modelled as a function of altitude), and some other stuff. These are, despite being a bit complicated, straightforward equations. The person who had made this model didn't write the equations, though, they instead made a Simulink sub-model for it with a bunch of addition, multiplication, and division blocks in a ratsnest. I think the Simulink approach should be used when it brings clarity to the problem, and should be abandoned when it obscures the problem. In this case it took a ton of mental energy to reassemble all of the blocks back into a simple closed-form equation and then further re-arranging to verify that it matched the textbook equation.

buescher 2y ago
I had an intern do something similar with an electromechanical machine. I'd all but written the equations out for him but he found drawing it out in Simulink in the most fundamental, primitive blocks to help him understand what was going on . I don't get it either. A related phenomenon seems to be people who don't want to "wire up" schematics but attach named nets to every component and then draw boxes around them.
- tonyarkles 2y ago
  > people who don't want to "wire up" schematics but attach named nets to every component and then draw boxes around them Lol there are a few things that I am highly intolerant of and this is one of them. The only place where I'm generally ok with that approach is at the input connectors, the microcontroller, and the output connectors. Same philosophy as I said before though: "if it brings clarity draw it as a wired up schematic; if it turns into a ratsnest use net labels to jump somewhere else". Having every component in a separate box with net labels will generally obscure what's going on and just turns it into an easter egg hunt.
  - buescher 2y ago
    Also, part of the style seems to be to contort any actual schematic to fit in the box. I like to ask "if you wouldn't put it on its own page so you could draw it clearly, why did you draw a box around it?".
  - foldr 2y ago
    I don't really get this point of view. Take an I2C bus, for example. Isn't it easier to read the schematic if all the components on the bus have two pins connected to wires labeled 'SDA' and 'SCL'?
    - tonyarkles 2y ago
      Yeah, there’s a balance here. There are common nets like SDA, SCL, GND, VCC that make sense to have as global nets. And then there’s actual circuits where it makes more sense (for understandability) to not do it like that. Here’s an example that I think takes it too far: https://cdn.sparkfun.com/datasheets/Dev/LilyPad/LilyPad-MP3-v15a.pdf https://cdn.sparkfun.com/datasheets/Dev/LilyPad/LilyPad-MP3-... - The audio jack (line level) could have just sat to the right of the codec and been directly connected to it to make it clear that it’s just a direct output - the speaker amplifier could be directly connected to the audio jack as well. I spent a lot of time looking around to figure out where it actually connects to; I figured it would have its input connected to the MP3 codec and didn’t realize that it would be connected through the micro switches inside the headphone jack (which makes sense now that I see it) - the SD card slot could either be connected directly to the codec or could have better names on the nets. When I see MOSI, MISO, and SCK I assume that they’re connected to the main MCU. Even more confusing, there’s an SD-CS that is connected to the MCU but not the rest of the SPI pins Overall I’d probably give this one a B. It’s by no means the most egregious I’ve seen but it also obscures the signal flow pretty badly. Other things I would probably consider doing: - better clustering of pins on the MCU by function. The switch inputs and LED outputs that connect to the rotary encoder are all over the place. Most tools allow you to move the pins on microcontrollers around at will - the FTDI block could move onto the first page. The DTR pin could use a bit of explanation that it’s tied to the reset circuit. Not their fault in this one but the naming inconsistency between FTDI-RXI and TRIG4/TXO is confusing until you figure out that the pin is meant to be either a GPIO or a UART pin. The name doesn’t make it clear that it goes to the FTDI chip because it’s inconsistent with the rest of the FTDI-xxx names but that’s because most ECAD programs handle net names poorly anyway Edit: one more thing that really bugs me about this schematic: the Vbatt net leaving J1. It’s labelled but not with any kind of flag or loose/unterminated line that would indicate that it’s connected to the net leaving U2. And further with that, the fact that VIN on U2 comes only from the FTDI connector on the second page (I think…)
mighmi 2y ago
Where can I read about your project or hear your tangent?
- tonyarkles 2y ago
  I'm hoping at a minimum get my thoughts written out while I'm flying this weekend! The quick gist is that Jupyter is frustrating for me because it's so easy to end up in a situation where you inadvertently end up with a cell higher up in your document that is using a value computed in a cell further down. It's all just one global namespace. In the Julia world with Pluto they get around this by restricting what can go into cells a little bit (e.g. you have to do some gymnastics if you're going to try to assign more than one variable in a single cell); by doing it this way they can do much better dependency analysis and determine a valid ordering of your cells. It's just fine to move a bunch of calculation code to the end/appendix of your document and use the values higher up. The idea I've been chewing on comes somewhat from using Obsidian and their whole infinite canvas idea. It seems like using ideas from Pluto around dependency analysis and being able to also determine whether the contents of a given cell are pure or not (i.e. whether they do IO or other syscalls, or will provide outputs that are solely a function of their inputs) should be able to make it easier to do something... notebook-like that benefits from cached computations while also having arbitrary computation graphs and kind of an infinite canvas of data analysis. Thinking like a circuit simulator, it should be possible to connect a "scope" onto the lines between cells to easily make plots on the fly to visualize what's happening. Anyway, that's the quick brain dump. It's not well-formed at all yet. And honestly I would be delighted if someone reads this and steals the idea and builds it themselves so that I can just an off-the-shelf tool that doesn't frustrate me as much as Jupyter does :)
  - sterlind 2y ago
    it sounds like the ideal solution would be something functional (so you have a computation graph), pure (so you can cache results) and lazy (so order of expressions doesn't matter.) why not Haskell? or even a pure/lazy subset/variant of Julia, if you want to ditch the baggage of Haskell's type bondage? you could ditch explicit cells entirely, and implement your "scope" by selecting a (sub)expression and spying on the inputs/outputs.
singleshot_ 2y ago
One cool thing about, for instance, density altitude calculations or runway length calculations, is that you can break the parts of the algorithm down graphically do pilots can trace through datapoints to get an answer without even having a calculator. See many pilot operating handbooks for examples.
- bandrami 2y ago
  Also works for power/moment data on marine freight, in fact I used to have a job at a shipyard drawing those.