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OpenVent controller PCB, version A (KiCad) ported from version 2.7 (Altium, incomplete), 2020-10-20, by Jeff Sutherland [email protected]
All files for the Power Board are in the subfolder called "OV_Power". All control/main board files are in this folder level. Electronic system diagram and overall device system diagram can be found here: https://docs.google.com/presentation/d/e/2PACX-1vRULcGT6Jc9GJDVb21LnrkGW9OiDjC7QJ2lRb0DsiA6KYFimniAMwYWqoMfq-0fJhvekxmhCl915fU4/pub?start=false&loop=true&delayms=3000&slide=id.gb10047446c_0_106 Also found by clicking "build" on https://openventbristol.co.uk/
Altium conversions aren't perfect but most everything is here. Because the schematic was incomplete and would not pass validation in Altium due to not being complete a few things didn't make it across symbol-wise. These will have to be re-created in KiCad, but this is a trivial exercise. Of more import is the assigning of properties to all of the symbols in the schematics so a sensible Bill of Materials may be generated directly from the schematic or finished PCB layout.
All of the footprints that were currently in the Altium PCB came over and are stored in the project footprint library. These do not necessarily match the schematic since the Altium PCB design reflects a former version of the schematic as it had not been updated as yet. So there is still much to do before we can begin the process of creating the layout. New mechanical information is needed (see project documents). The PCB layout for the former version, stored for reference in the file "OpenVent_PCB-PcbDoc.kicad_pcb" does not reflect the correct mechanical outline nor placement of components. The PCB footprints from the Altium design are missing information needed by KiCad so if replacements are not available in the standard KiCad libraries then these will have to be fixed.
TO DO's: Complete schematic: a. Add BOM info to all symbols b. Complete circuit design c. Validate design
Process Board layout: a. load in missing footprints (use KiCad libraries, avoid creating footprints by hand if at all possible, if needed, fix existing ones.) b. Update PCB board outline, mech drill holes, and update placement and routing keepout areas c. Complete board placement and routing. d. Check association of footprints and 3D bodies; prepare STEP file of 3D image of board for mechanical group.
When creating symbols or updating fields in the schematic use the following patterns for adding information to symbols in the lib or schemo:
Field 0 is always 'Reference' Field 1 is always 'Value' Field 2 is always 'Footprint' Field 3 is always 'Datasheet'
These cannot be changed as they are required by the system. The remaining fields can be freely defined. So in the case of OpenVent we need to standardize how these are used to make sensible BOM generation possible. For example, something like this scheme could be used:
Field 4 is defined as 'Val' (resistance, capacitance, inductance, etc.) Field 5 is defined as 'Voltage' Field 6 is defined as 'Tolerance' Field 7 is defined as 'Watt' (usually just for resistors) Field 8 is defined as 'Current' (usually for diodes and inductors) Field 9 is defined as 'Mfr' (manufacturer name) Field 10 is defined as 'Mfr_PN' (manufacturer's part number) Field 11 is defined as 'DistName' (this would be Farnell, DigiKey, etc.) Field 12 is defined as 'Dist_PN' (distributor's part number) Field 13 is defined as 'Detailed' (detailed description of part)
Optional fields can be added at will in the schematic to suit the needs of the design or documentation efforts.
Notes on using KiCad:
When setting up your KiCad installation you should also clone the repositories for the symbols, footprints and 3D models and refer to those in your 'manage libraries' settings rather than using the default libraries that came with your version of KiCad. See github.com/kicad.
Do not just add symbols to the design from the KiCad standard libraries. The symbols there are basically just "templates". Copy standard symbols to a project library then add BOM and footprint info to the symbols if needed.
Avoid creating your own footprints if at all possible. Most every IC in common use already has a standard footprint in the KiCad libraries.
All footprints should be kept in a local project library. If modifications need to be made to paste or solder mask layers to deal with process issues copy footprints to another library and tag that library with the name of the PCB vendor so that managing artwork fudging among vendors can be easily sorted.
After footprints are pulled into the PCB design from the standard KiCad libraries they may be exported to a local library to facilitate modifying any of their shapes to meet DFM requirements of a particular vendor. Simply export the footprints to a project library from the PCB editor once the design has been transferred from the schematic and all the footprints have been accounted for. There's no need to manually copy footprints from the KiCad libraries.
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