How do I make microcontroller circuit diagrams

Draw the circuit diagram correctly

From the Mikrocontroller.net article collection, with contributions by various authors (see version history)

Based on the following thread [1], this article collects tips for properly drawing circuit diagrams. It helps to look at other authors' schematics that are "tidy".

Rules [edit]

  • Maintain clarity; not like that; more like that.
  • Place component names and values ​​in a legible position
  • Use supply symbols and do not rotate, if possible and sensible (GND points downwards, VCC upwards)
  • Do not lay cables through other components
  • Only horizontal and vertical lines, only 90 ° angle. 45 ° in special cases. z. B. tap voltage at a shunt, separate out a signal from a bus
  • Use network identifier for important networks. Important networks are:
    • Lots of pins / components on the network
    • Increased demands on the layout, e.g. B. high current, high frequency, sensitive input, etc.
  • Rotate, move, mirror components to avoid line crossings
  • Components should represent the function in the circuit diagram as clearly and logically as possible. The arrangement of the pins in the circuit diagram has nothing to do with the physical arrangement of the pads on the case, because that's what the case is in the layout, see this forum post.
  • Busses make the circuit diagram clearer, but use network identifiers as mentioned above
  • Tensions that are as positive as possible above than below
  • If possible, the inputs on the left and the outputs on the right
  • As few line crossings as possible, but not at the expense of excessive line length
  • As few cable bends as possible thanks to component placement that is sufficiently far apart and that is mutually compatible
  • In the case of critical circuits, lines may be routed as they should be in the layout, i.e. common star points or the like
  • The latter also requires that the components are placed appropriately according to their function. For example, the backup capacitors, which are often clamped as directly as possible next to an IC via its supply voltage, also draw directly next to the IC in the circuit diagram so that it is discreetly indicated where they should be placed.
  • As sensible as possible division into function blocks, if it is larger than a sheet, so that not too many lines cross the sheets. If the selected software allows it: Put each function block in a separate hierarchical sub-circuit diagram.
  • Circuit diagrams contain connection lines (signals) and not a collection of network names. So should it Not look! More like that.
  • "Zero Ohm" resistors, which are used as bridges, or direct wire bridges also belong in the circuit diagram, and should not be shyly withheld. Reason: They are often good points of orientation and measurement when troubleshooting, which should not be ignored. In addition, their appearance in the circuit diagram also leads to an appearance in the parts list (BOM, Bill Of Materials), which helps production, since zero ohm resistors and bridges also have to be included in the inventory.

EXTRA for Eagle users [edit]

  • A component has an identifier (NAME) and a value (VALUE). Both should be present.
  • Both should be arranged in such a way that both can also be read. (Use SMASH!)
  • Placing NAME and VALUE sensibly in the library - usually makes SMASH unnecessary. It works particularly well with ALIGN: CENTER.
  • For GND networks, you should use the appropriate symbols, do not change the network name in a tiny little bit, and you should not draw them all over the circuit diagram.
  • The same applies to other global networks such as VCC.
  • There are also schematic frames (library frames) that can also be filled out.
  • You don't have to draw everything on a schematic page (if you have a full version)
  • You can place several schematic frames on one page and print them separately (with WINDOW instead of FULL) (if you don't have a full version)
  • When printing the circuit diagram, the squiggles around the electrical connections should be SWITCHED OFF (Layer 93 - Pins). This layer is used very little in practice.

See also [edit]

Links [edit]