3 ms·

Sometimes, and it depends what you're trying to convey. Take a system with multiple I2C devices - with each device on a different sheet, it becomes difficult t

Sometimes, and it depends what you're trying to convey. Take a system with multiple I2C devices - with each device on a different sheet, it becomes difficult to tell that you might have bus contention issues.

foldr 2y ago
Is it? You can just count the number of devices connected to the I2C bus. That seems easier than if you had to follow a bunch of tangled lines.
- bobmcnamara 2y ago
  > You can just count the number of devices connected to the I2C bus If everyone working on it has the software, they can count easily and accurately. When I started and still sometimes today "just counting the number of devices" requires visiting each sheet of the schematic, then hoping you didn't miss one. > That seems easier than if you had to follow a bunch of tangled lines. Today's software will let you draw a single bus connection between all bus devices. > That seems easier than if you had to follow a bunch of tangled lines. The problem is generally that if you choose to put some things near each other, you're choosing to put other things further away. In many cases the I2C bus itself has little to do with what the I2C devices do, so by drawing a single I2C bus or pair connecting all the devices with splitting them up with a named bet, you're choosing to make those other things harder to show. This may or may not be appropriate for the design.
  - foldr 2y ago
    >If everyone working on it has the software, they can count easily and accurately. Any IC on the I2C bus will have pins labeled SCL and SDA, so you can easily just go through all the ICs and count how many have those pins. It might be slightly tedious with a paper schematic, but it's hardly impossible. It still strikes me as easier than doing the same thing with unlabeled pins that are connected directly in the schematic to the UC's I2C pins. >In many cases the I2C bus itself has little to do with what the I2C devices do, so by drawing a single I2C bus or pair connecting all the devices with splitting them up with a named bet, you're choosing to make those other things harder to show. I don't quite understand what you're saying here. Labelling a pin with SDA or SCL makes it clear that it's connected to the I2C bus. What I'm saying is that I don't see any value in drawing a line connecting the pin to all the other SDA/SCL lines. That's completely independent of how you lay the schematic out or split it into functional blocks.
    - bobmcnamara 2y ago
      > It might be slightly tedious with a paper schematic, but it's hardly impossible. What may only be slightly tedious for you will often be error-prone for someone else. >I don't see any value in drawing a line connecting the pin to all the other SDA/SCL lines. The value is that the entire bus is visible at a glance. All conflicts are visible, and contention sources understandable. Though, you can also put this information in a note/table. >That's completely independent of how you lay the schematic out or split it into functional blocks. What I mean is that it's often also valuable to split a schematic out along functions rather than busses. If you have an I2C ADC with a bunch of analog stuff connected to it, that might fit its own sheet better. But if your weather station I2C bus has several simple devices like Flash, ALS, humidity sensor, RTC, barometer, and thermometer, placing them together on one sheet may make sense. I just mean tidyness varies with the contents of the room.
      - foldr 2y ago
        I am not really understanding the "at a glance" part. If there are no labels then you have to follow the wires. That seems more difficult, not easier. You can split out all the components on the I2C bus onto a separate sheet (or not) regardless of whether you label or SDA and SCL lines or connect them with wires.
        bobmcnamara 2y ago
        If the complexity of the attached subsystem is low enough, the wires can be used as a feature not a bug, like a map. Imagine a home network diagram with a router, switches, and computers. You could draw each on their own sheet with names for each cable, but the purpose of each cable is clear from what it connects.

foldr 2y ago

Is it? You can just count the number of devices connected to the I2C bus. That seems easier than if you had to follow a bunch of tangled lines.

bobmcnamara 2y ago
> You can just count the number of devices connected to the I2C bus If everyone working on it has the software, they can count easily and accurately. When I started and still sometimes today "just counting the number of devices" requires visiting each sheet of the schematic, then hoping you didn't miss one. > That seems easier than if you had to follow a bunch of tangled lines. Today's software will let you draw a single bus connection between all bus devices. > That seems easier than if you had to follow a bunch of tangled lines. The problem is generally that if you choose to put some things near each other, you're choosing to put other things further away. In many cases the I2C bus itself has little to do with what the I2C devices do, so by drawing a single I2C bus or pair connecting all the devices with splitting them up with a named bet, you're choosing to make those other things harder to show. This may or may not be appropriate for the design.
- foldr 2y ago
  >If everyone working on it has the software, they can count easily and accurately. Any IC on the I2C bus will have pins labeled SCL and SDA, so you can easily just go through all the ICs and count how many have those pins. It might be slightly tedious with a paper schematic, but it's hardly impossible. It still strikes me as easier than doing the same thing with unlabeled pins that are connected directly in the schematic to the UC's I2C pins. >In many cases the I2C bus itself has little to do with what the I2C devices do, so by drawing a single I2C bus or pair connecting all the devices with splitting them up with a named bet, you're choosing to make those other things harder to show. I don't quite understand what you're saying here. Labelling a pin with SDA or SCL makes it clear that it's connected to the I2C bus. What I'm saying is that I don't see any value in drawing a line connecting the pin to all the other SDA/SCL lines. That's completely independent of how you lay the schematic out or split it into functional blocks.
  - bobmcnamara 2y ago
    > It might be slightly tedious with a paper schematic, but it's hardly impossible. What may only be slightly tedious for you will often be error-prone for someone else. >I don't see any value in drawing a line connecting the pin to all the other SDA/SCL lines. The value is that the entire bus is visible at a glance. All conflicts are visible, and contention sources understandable. Though, you can also put this information in a note/table. >That's completely independent of how you lay the schematic out or split it into functional blocks. What I mean is that it's often also valuable to split a schematic out along functions rather than busses. If you have an I2C ADC with a bunch of analog stuff connected to it, that might fit its own sheet better. But if your weather station I2C bus has several simple devices like Flash, ALS, humidity sensor, RTC, barometer, and thermometer, placing them together on one sheet may make sense. I just mean tidyness varies with the contents of the room.
    - foldr 2y ago
      I am not really understanding the "at a glance" part. If there are no labels then you have to follow the wires. That seems more difficult, not easier. You can split out all the components on the I2C bus onto a separate sheet (or not) regardless of whether you label or SDA and SCL lines or connect them with wires.
      - bobmcnamara 2y ago
        If the complexity of the attached subsystem is low enough, the wires can be used as a feature not a bug, like a map. Imagine a home network diagram with a router, switches, and computers. You could draw each on their own sheet with names for each cable, but the purpose of each cable is clear from what it connects.