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Difference between revisions of "Public:Schematic Conventions"
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Long answer short, dots on all 3-way intersections, no dots on 4-way intersections. A dot means that the wires connect, no dot means that there's no connection. ''Keep reading to find out why those statements should not contradict each other in your design.'' If you encounter a 4-way connection, in which both wires crossing at the perpendicular angle are connected to each other, separate it into two 3-way connections instead. | Long answer short, dots on all 3-way intersections, no dots on 4-way intersections. A dot means that the wires connect, no dot means that there's no connection. ''Keep reading to find out why those statements should not contradict each other in your design.'' If you encounter a 4-way connection, in which both wires crossing at the perpendicular angle are connected to each other, separate it into two 3-way connections instead. | ||
| − | + | Take a look at these pictures for some examples: | |
| − | [[File:116|70px]] | + | [[File:117|70px]] * Left vertical wire connects to 3 but not 1. |
| + | * Right vertical wire connects to 1 only | ||
| + | * 2 connected to GND and not 3 | ||
| + | |||
| + | [[File:116|70px]] * Left vertical wire connects to 3 but not 1 | ||
| + | * Right vertical wire connects to 3 only | ||
| + | * ''2 needed to connect to both 3 and GND, so that's separated into 2 different connections: 3 to GND and 2 to 3'' | ||
| + | * '''do not''' simply put a dot on the 4-way intersection to show the connection between 3, GND, and 2 | ||
==Direct Wire Connections== | ==Direct Wire Connections== | ||
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Include information in these fields: | Include information in these fields: | ||
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| + | ''Coming soon...'' | ||
=Part Information= | =Part Information= | ||
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[http://kicad-pcb.org/libraries/klc/] | [http://kicad-pcb.org/libraries/klc/] | ||
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=Recommended Reading= | =Recommended Reading= | ||
[https://electronics.stackexchange.com/questions/28251/rules-and-guidelines-for-drawing-good-schematics Rules and Guidelines for Drawing Good Schematics] | [https://electronics.stackexchange.com/questions/28251/rules-and-guidelines-for-drawing-good-schematics Rules and Guidelines for Drawing Good Schematics] | ||
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Revision as of 14:38, 9 January 2019
Table of Contents: {toc}
Our team is in the process of creating and implementing standards for all of our electrical design and CAD. This is being done in an attempt to reduce errors in manufactured boards, make it easier for other members to edit boards that were already created, and make the finished CAD look presentable. We will also create a project template to set the DRC (Design Rule Checker) to our standards and make all our boards follow Bay Area Circuits' manufacturing constraints.
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All content below this point is under construction. Follow all conventions given here and be aware they may not cover all situations.
General Advice for Clean Schematics
Be consistent with whatever conventions you choose, if we do not require a specific standard!
If you think something is hard to read or confusing, and you are following whatever conventions listed here, please post your dilemma in the #elec-cad channel on ((Slack)).
Net Naming
All nets with more than two pins should be named with a descriptive name.
Net names should only contain capital letters, numbers, and underscores. Net names should never contain spaces.
More guidance on net naming will be provided at a later time
Power Rails
No VCC/VDD. Net names should indicate the polarity and voltage of the rail. If the zero voltage reference of the rail is not the net named "GND", the net name of the power rail must reflect this.
- Voltage Rail should be near the top of the schematic
- *Voltage symbol usually points upwards
- *In the case of a voltage output, e.g. from a DC/DC converter, voltage symbol may point sideways
- GND Rail should be near/at bottom
- *GND symbol always points downwards
- If there is a decimal point in the voltage, use the convention of replacing the decimal with V for voltage, e.g. +3V3 describes +3.3V
I2C/SPI
Will expand on this later
UART
It is very easy to get mixed up with UART nets, be thorough and double check your work!
UARTx_Source_to_Destination
Examples
Put some examples here
Graphical Considerations
Schematics are the most critical piece of documentation for a PCB. They are read by both ECAD software and fellow engineers. The schematic should clearly illustrate its functionality, be easy to read, and contain enough information so that it is easy to order parts and assemble the finished PCB.
More information will be provided at a later time
Wire Crossings
Long answer short, dots on all 3-way intersections, no dots on 4-way intersections. A dot means that the wires connect, no dot means that there's no connection. Keep reading to find out why those statements should not contradict each other in your design. If you encounter a 4-way connection, in which both wires crossing at the perpendicular angle are connected to each other, separate it into two 3-way connections instead.
Take a look at these pictures for some examples:
70px * Left vertical wire connects to 3 but not 1.
- Right vertical wire connects to 1 only
- 2 connected to GND and not 3
70px * Left vertical wire connects to 3 but not 1
- Right vertical wire connects to 3 only
- 2 needed to connect to both 3 and GND, so that's separated into 2 different connections: 3 to GND and 2 to 3
- do not simply put a dot on the 4-way intersection to show the connection between 3, GND, and 2
Direct Wire Connections
Wires should be as straight as possible to make it easier for the eye to follow.
Routing from Components
Route lines should come straight out of components, as opposed to immediately making an angle. This makes it easier to move components later on.
Prevent Overlapping
Components, reference designators, and part values must never overlap anything. The only thing that wires can cross is other wires. Text comments should not overlap anything.
Net Coloring
While net coloring can be useful to easily identity and follow nets around a schematic, the schematic should be completely intelligible without net coloring. This is because the schematic will most likely be printed in black and white if it is printed.
Paper Size and Title Block
Paper size: ANSI A (8.5" x 11")
We need to be able to print out all of our current schematics at any time as a backup
Diptrace archives may not use any standard paper size, as we did not enforce the standard on our boards when we used it.
Title Block: Kicad Default, Diptrace --TBD-- now defunct, do not use
Include information in these fields:
Coming soon...
Part Information
Using just the schematic, anyone should be able to determine which parts should be ordered to assemble the board. To achieve this, the following guidelines should be followed to ensure that all necessary information is included in the schematic.
Still working on this
This is an example for a Schottky diode. The value is the reverse voltage value, one of the most important values for Schottky diodes. The P/N field had to be added to the Fields by clicking the blue + button.
Symbol Creation
Look, please make symbols that aren't shit or look like shit. If you have questions, please refer to the Kicad Library Conventions for now.