developer notes on tools we use or thinking about
Recommended parts
During sch + layout design there are often compromises. Sometimes designer hesitates to add some board optimization that would increase BOM linecount, such as using both BAV99 and BAW56 instead of just BAV99. BOM linecount and partcount has related manufacturing costs, naturally, but usually fairly small. In general I recommend to make optimizations, a few added BOM items are no problem.
Some notes: think about parts below and use them with cheers:
- SOT23 diodes BAW56 common anode and BAV70 common cathode besides the BAV99 (clamping 2 signals to GND and +5V) often lays out better with a common anode sot23 and a common cathode sot23 instead of 2 BAV99
- SOD80 diodes: these can be picknplaced as well (eg. LL4148 or the 5V1 zener)
- DPAK FETs and IGBTs (instead of TO-220)
- sot89 and DPAK voltage regulators
- jumpers and headers: 2x7 header instead of 2x6 seems to be more common. DIP14 layout is also useful to get signals out of the board through a cable or to an elevated baby board (there are nice sockets. We use 2x6 connectors made from quality DIP14 sockets cut to half and 1+1 pin cut to test the LCD operation on boards that have no LCD header). For flying loom (which works very nice with some hotmelt glue and sealing rubber ring to get cable through frontplate), random pad placement also works.
- ULQ2003 and similar lowside drivers (marvellous part. We avoid TPIC6A259 in future)
- 74AHCT... chips with 6V supply drive FET and IGBT gates nicely (max 2 gatedrive per chip preferred). TSSOP package is nice (but we also use SOIC)
- NPN and PNP (sot23, DPAK) transistors are also welcome. Some (PDTC...)have internal base resistor.
- ...
Spice SW
- free spice clones (like acs)
- ltspice
- http://focus.ti.com/docs/toolsw/folders/print/tina-ti.html Texas released a new free spice (with GUI and libraries)
PCB SW:
Eagle schematic and PCB editor (and it's license terms!) from http://www.cadsoft.de/
I use the Eagle 4.11 professional license, but eagle with any license can view sch or pcb, and any can edit the one-page (therefore a bit clumsy looking) schematic. Eagle is a relatively shitty program. The lack of some very simple functions make your life hard.
Eagle wishlist:
- when editing libraries, you cannot select a symbol or package from another library. Just drag and drop the package to the library you are currently editing. I tried drag and drop (that was the first way I tried), it did not work. However opening one destination library for editing, and browsing source lbr in the control panel treebrowser helped: right click on the symbol: copy to library
- eagle should show the component values (not just name and package) in the status bar when component is viewed (with the eye icon), this brings us to:
- shared highlight functionality between brd and sch (without typing the show command)
- eagle should show the name of the routed trace (!!! unbelievable how they forget this, maybe they use PADS for their own work)
- it's really stupid that we cannot declare 2 subnets are connected (without merging the names, because merging names is irreversible. Grouping supplies nicely on sch helps somewhat, because rename "segment" on sch works. )
eagle working list:
- Separate clearance for polygon fill (eg. 12 mil, the keyword is edit-isolate) and minimal DRC clearance (eg. 8mil) is available.
- Copy sch sections to other design: found it in cadsofts support channel. The procedure is very odd, First close the board!!! Then make selection, cut it, then delete it. Now paste to new sch sheet. Open board again, run ERC. If not all devices in a package is moved a new component will be added and the ERC will fail.
GEDA GNU electronic design automation.
These software are good for simple design. VEMS team mostly uses Eagle. Autorouter functionality is poor, but 2 layer boards must be routed manually for sane result anyway :-)
do you know how to share info between PADs and Eagle schematics and layouts? Have links? A friend insists on PADs (which he paid serious money for) and would make smaller boards (eg. stepper-driver for a special app, special form-factor).
Spice and clones (eg. acs) for simulation
HW:
scopes (like Vellemann K7103), signal generators
Virtual trigger signal generator by Ray Hall, handles the most common stock trigger arrangements:
http://www.autronic.com/software/SignalGen.zip
Lab equipments
http://www.e-lab.de/index_en.html
Interesting links, practices, examples:
ManuFacturing links, eg.: ManuFacturingInHungary
See also MechanicalDesign, BuildProcedures
4.11 Eagle Lite Sources
AVR simulation (should have it's own page?)
- AVRstudio works quite well, reads objects in coff format. However it is winblows only and not suitable for automatic regression-tests (only manual stepping of code)
- simulavr and gdb should be OK for measuring cycles while everything happens in memory: the IO port (and timer interrupts etc..) handling is very incomplete for Atmega128
- http://compilers.cs.ucla.edu/avrora the new canon, check this out!!! Should be nice and powerful.
See also
![[ PCB tracewidth wisdom2]](http://www.apcircuits.com/assets/images/copper1.jpg){kind=link}