ENGINEERING JOURNAL

Jingyan Ling

06/27/2019 (Thur)

• Compile OldRoCo repo
  • Record of modification:
    • ++line 8 of vstart.sh
    • --> pip install -r requirements.txt --user
• Export paperbot dxf file : graph-silhouette.dxf to OnShape
  • Record of Tips:
    • Onshape does not read dxf file as its own saved unit. Manual settings needed when import.
    • 
• Draw circuit diagram as CAD on Onshape
  • Multiple connection approaches:
    • Cross shape of 0.039 in
    • Cross shape of 0.049 in
    • Octangular shape of 0.049 in
    • 
    • 
  • Note and issue:
  • Octangular shape is the best connection approach so far, but none of approach has stable conductivity. More research is needed.
  • Scratches can be made easily when attaching microcontroller to the sheet. Potential disconnection may occur due to such scratches on metal layer.
• Export 2D CAD drawing with PCB to SVG for silhouette cameo
  • Record of Tips:
    • OnShape unit need to be consisted with unit setting in Inkscape (default: mm)
  • Plugin Inkscape-silhouette cannot take multiple types of trace for cutting.
    • Different trace (especially cut and etching) need to be sent separately. Use coordinate tool of Inkscape to ensure separated cuts have same origin.
  • TODO:
    • Cut and etching from same Inkscape file

06/28/2019 (Fri)

Connection and fabrication approach confirmed !

• Confirm that copper tape has better conductivity than aluminum sheet when attaching microcontroller pins through H-shape cut

  • Copper tape is harder to be scratched, which provides less risk of disconnection during assembly.

• Etching on copper type isolates connections

• Research on PCB editor

  • EAGLE
    • EAGLE cannot import .pcb file
    • svg can be exported but not imported
    • Custom library needed if doing schematic design
  • KiCad
    • Can import .pcb file
    • svg can be exported but not imported
  • LayoutEditor
    • support multiply file type
    • svg can be exported with different color makers as multiple layers
    • include open-sourced auto-router freerouting

• Auto-routing package:

  • TopoR
  • Python-PCB
  • FreeRouting

• Approaches:

  • A. convert SVG/DXF file to schematic/board design of PCB. Use KiCAD or EAGLE to do auto routing.
  • B. develop algorithm on auto routing for single layer svg/dxf file. (path finding problem)

Approach A

• Use regular shape board for PCB in EAGLE/KiCAD

  • image processing: divide the shape of paperbot to multiple rectangles (ezdxf)

  • Pull required connections and place additional header pins around edges of each rectangle

• Make each connection pin to be two parallel connections so auto-router does parallel trace for each wiring.

  • Etching a pair of parallel trace provides isolation, and leave the space between traces to be conductible.

• Build Library for schematic design

  • Schematic design helps with router to know desired connection
  • Additional header pins at each side of kink mark

06/29 & 06/30/2019 (Sat & Sun)

Approach B

• Potential needed functions of packages

  • A package draws on DXF file through script
  • A script that pulls out pins' coordinate on paper chassis
    • Or a image process package (OpenCV) that reads pins' coordinate on paper chassis
  • A package solves multi-node path finding problem*

Record of Research

• Python Pathfinding package:
  • pathfinding
• Python DXF editor:
  • ezdxf
  • dxfgrabber
    • Note: able to grab simple geometry from file
  • sdxf
• Going through tutorials of ezdxf
  • All lines on paper spacelayer0

07/01/2019 (Mon)

• Continue the dxf processing with 'graph-silhouette.dxf'

Record of tips:

• Put circuit design on a new layer of dxf drawing

  • check doc about layers here

• Use block feature to draw similar pattern

  • check doc about block here

• Blocks are symbol in Inkscape. Convert symbol to path

  • Edit > Clone > Unlink Clone (Shift+Alt+D), and you have a group, ungroup (Object > Ungroup, or Shift+Ctrl+G) and edit

• Convert text to path

  • Path combine (Ctrl+K)

• msp.delete_enetity('__') to remove existing entity

• Test fabrication with different drawing settings

  • Layers can be cut separately by toggling visibility
  • Set cuts with same intensity and feedrate on same layer
  • Entities' layer can be changed through Entity.dxf.layer

07/02/2019 (Tue)

• Continue the dxf processing

• Following tasks can be completed by running the code:

  • Able to detect pin center coordinate
  • Able to draw arbitrary shape around the pin center
  • 

• • Issue & TODO

  • Convert dxf image to matrix

  • Explore pathfinding package

  • pathfinding package solve path finding problem by shortest path algorithm, one point to another

  • To solve multiple nodes problem, use concept from reinforcement learning

    • Build Q function that represents total reward of choosing certain path to be solved first
    • Update Q function in a loop with certain amount of episodes
    • Choose the order of solving paths randomly, and add possibility of choosing it from Q function
    • Exploration-exploitation method

• To solve the problem "convert dxf to matrix" for pathfinding:

  • Have tried:
    • Export to png and read file by OpenCV
      • Resolution problem: single point does not represented as a pixel in png
    • TODO:
      • create an empty matrix and fill in numbers with the information of each lines' start and end point

07/03/2019 (Wed)

• dxf processing completed

• Convert dxf to matrix with resolution (270X210) (mm)

  • Potential issue:
    • the pathfinding package is based on pixel
    • When round up the line's start and end point, the accuracy of pin position is low

• Apply single point to point path finding

  • Able to draw the path on matrix
  • Able to draw the path on original dxf file

• 

• TODO:

  • Write out algorithm for multi-node path finding
  • break single circuit trace to parallel traces
  • solve the accuracy problem

07/05/2019 (Fri)

• Write out algorithm for multi-node path finding
  • pseudo code:

 for (episode in E):
    set initial state s (choose first pair of nodes to connect randomly)
    find a path
    update map
    while not every connection is built:
      choose next connection
      find a path
      update map
      retrieve cost (length of path)
    update Q (as sum of all cost)  
	

• Q here represents total cost of certain choice of path finding order.

  • Cost defined by length of path
  • If path cannot be found, cost 1000

• Input: NX2X2 array specifies desired pin connections

• Research on KiCAD import needs and python API

07/08/2019 (Mon)

• Debug multi-node path finding:
  • some obstacles are ignored
  • too close to each other
• Able to show the learning process:
  • Trying different combination of solving order
  • Try to give the best order of solving multiple path

Auto-routing learning process:

• 

• Comparison between episodes and choose best combo of paths

• 

Issues and TODO

• Path export from optimization is messed up
• Obstacles setting are incorrect

07/09/2019

• Finish up path-finding approach (Approach B)

• Only draw the best path on dxf when solution is found for every route.

• 

• Throw warning once a route cannot be found

• 

• Research on Approach A

  • KiCAD 5 does not have built-in auto-router

    • Have to use FreeRouting

  • FreeRouting does not have python API

  • Parent package of FreeRouting, LayoutEditor has multiple editions

    • Part of LayoutEditor is open- source
    • A large amount of of its website are broken, source and interface are unavailable

• Other auto-routers are not open-source

Approach A

• 1. Use LayoutEditor python API to use FreeRouting
• 2. Use KiCAD 5 python API to sue FreeRouting
• 3. Use KiCAD 4 python API to use builtin auto-routing

1

• FreeRouting input format: dsn, lef, def

• FreeRouting output format: ses, def

• FreeRouting can take arbitrary board outlines shape

• Edit library manually and test routing

• 

• TODO:

  • If can run KiCAD 4 from python
  • Check FreeRouting API, see if a acceptable file can be generated from things on hand

07/10/2019

Approach A

• Import to PCBnew issue:

  • Dimension of board outlines are incorrect
  • Pins does not fit in original drawings
  • (solved. Microcontroller footprint was incorrect)

• pipeline confirmed:

  • 1. Build symbol and footprint library for all required electrical element
  • 2. Sketch schematic design
    • .sch file
  • 3. Place elements in required position
    • .dsn file
  • 4. Import dsn file into FreeRouting and do auto-routing
    • .ses file
  • 5. Import ses file back to KiCAD and export as dxf file
    • .dxf file

• Manually tested pipeline till step 4

• Step 3

• 

• Step 4

• 

  • ISSUE:

    • Board outlines are not exported correctly to FreeRouting
    • Error: unable to find segment with an endpoint

  • Record of Tips:

    • To run FreeRouting from command line:

      java -jar freeRouting.jar [proj.dsn]

• TODO:

  • Finish with testing the pipeline manually
  • Achieve steps directly from script (Python API)

07/11/2019

• Solved Error unable to find segment with an endpoint

  • DSN file can only be exported for continuous closure outlines

  • 

  • Drawings like this drawing for paper cut is not acceptable for dsn file.

  • Change it either to close shape or remove it when import to KiCAD

• Solving Issue: FreeRouting is not reading edge cut layer from dsn

  • Work well on a sample dsn file
  • Issue with KiCAD output
    • Sample KiCAD project can output outlines properly.

• Issue found:

  • KiCAD cannot take single line cut. Closed shape needed.

07/15/2019

• 3 potential ways to solve the issue on KiCAD with internal cut

• Assume the position of each internal cut line is known

  • 1. Make internal cut a closed shape (original cut with thickness)
    • Pro: Easy to import routed circuit back to dxf cutter file
    • Con: Hard to make the cut itself a closed shape.
  • 2. Make internal cut outlines a block on certain layer and treat it as obstacle in auto-router
    • Pro: Easy to generate a block as obstacle in drawing
    • Con: Hard to import routed circuit back to dxf cutter file
  • 3. Put internal cut on different layer in KiCAD that can be read as obstacle in auto-router
    • Best solution for now if the auto-router will be able to read single cut line, but cannot be edge.cut layer for sure, otherwise board outlines cannot be found by KiCAD.

• Cut lines causing issues are marked in red.

• 

• Inkscape :

  • Object stroke to path can make everything looks like a bounding box

• Attempts:

• 1. Stroke every line, auto-router shows nothing, no error

• 

• 

• 2. Stroke every line, but has a larger boundary. auto-router shows nothing, error: cannot start a route inside of keepout area or boundary outlines

• 

• 

• 3. Stroke every line but make the boundary outlines not closed, and draw a larger outline. Auto-router shows nothing, no error

• 

• 

• 4. Stroke only outline but make the boundary outlines not closed, and draw a larger outline. Auto-router shows properly. (no way to do it from script)

• 

• 

• 

07/16/2019

• Fill and Stroke (Shift + Ctrl + F)

• Stroke to Path

• Union

• Break Apart

• Remove each outer layer (manually)

• Export

• 

• 

• 

• Consider success when export for auto-routing manually. Huge challenge expected when doing it from script.

• Work on script doing schematic design

  • Assume symbol and footprint downloaded
  • Package Using: skidl
  • Record of Tips:
    • Add custom library path that contains all symbols of electrical devices needed (NodeMCU)
    • Use attribute footprint to add footprint for such symbol
    • footprint syntax: 'footprint= libname.pretty: foot_print_name
    • footprint directory should be under the same directory where .lib file is.

07/17/2019

• Notice that even the drawings cannot be imported onto 'wiring' layer, but can be changed manually to 'wiring' layer after importing onto 'edge.cut' layer

  • Freerouting does not recognize wires that does not connect to any pins as obstacles.
  • 
  • 

• Work on script doing board design

  • Create New Board
  • Import DXF
  • Load Netlist .net file
  • Place modules
  • Export to .dsn file

07/18/2019

• Research on pcbnew API

  • Using package pykicad

  • Record of Tips:

    • Do not add segments, which will route connections
    • Different reference name need to be set for dsn export

  • Able to add footprint and net list into pcbnew.

  • TODO:

    • Import dxf as outlines from script
    • Export board as dsn

07/22/2019

• Research on multiple KiCAD Python packages

• package 3rd party list

• None can import dxf into pcbnew

• To import dxf into pcbnew automatically:

  • Create a python API by myself based on the c++ code
  • Draw lines directly in pcbnew by using line information in dxf

• Create a python script serving as Python API by drawing everything on pcbnew

• Successfully import dxf as outlines from script

• 

07/23/2019

• Solving issue: export .kicad_brd file to dsn file for auto-router

• No known Python API so far.

• schematic-file-converter

  • Take .sch file from KiCAD instead of .kicad_brd file

• Official bug report has been requested. Not targeted in current KiCAD scripting version

  • bug report

• Potential Solutions:

  • 1. Explore existing supported export API, and see if modification can be made based on existing API structure
  • 2. Learn dsn file specification and python library to generate dsn file based on design information