Actions
Forum Thread Details
  • Replies 31 replies
  • Subscribers 306 subscribers
  • Views 3638 views
  • Users 0 members are here
Related
See a helpful answer?

Be sure to click 'more' and select 'suggest as answer'!

If you're the thread creator, be sure to click 'more' then 'Verify as Answer'!

Inefficiencies in Hardware Bring-up Discussion

derail

Hello all,

I am an electrical engineering undergraduate currently in the process of starting my senior design project (capstone) with an idea based around solving test and debug inefficiencies in the hardware bring-up realm.

 

I’d like to start a conversation about what really grinds your gears at your workplace, or on your downtime at home, while designing, testing and validating new board designs. Any feedback is greatly appreciated!

 

To get things started here are some of the questions I really want to be discussed:

  • What type of information (and medium) do you have about a board while you are testing it?
  • Through your experience, what points in your testing workflow do you see as inefficient?
  • What is the biggest problem you’ve faced while performing bring-up on a new PCB?
  • What PCB design software did you use (KiCAD, Altium, Eagle, etc)?
  • What parts of your PCB design software did you find most helpful with bringing up a new board?

 

Thank you in advance to anyone that can provide feedback on this subject as it will really help my capstone team narrow what to build and help validate some of our potential ideas.

Cheers,
Darryl

Parents

  • That's a very ambitious undergraduate project.

     

    Experience is  what sorts out the good from the bad in this area.

     

    The biggest problem you get is a dead short across the power rails, closely followed by high current drain at low voltage on one or more power rails.

     

    Dead shorts are usually construction errors, common on prototypes. High current drain has myriad sources but reversed power rails and mis-connections are favorites

     

    Mitigations that help locate and fix faults are:

     

    • links on power rails so different parts of the board can be isolated
    • .test points (not just pads but actual scope/meter probe friendly ones like this: Farnell 2668701  )
    • debug LEDs and multi way connectors for logic analyser/scope/eyeball probing on spare processor/FPGA pins, critical nets, inter chip buses like SPI, I2C etc

     

    Mitigations that help avoid faults are:

     

    give power rails sensible names - banish Vdd and Vcc from symbol and net names and use names like V0, V3_5, V5_0, V5_0_filtered, V5_0_frontend etc.

    do proper design reviews (everyone says this good , hardly anyone does it well)

    use consistent net naming - keep signal names the same or logically related as nets propagate through complex hierarchical designs.

    don't use the libraries that come with CAD tools - design your own so that complex chips are broken up into blocks that represent design intent

    never sub contract PCB layout further than 2 desks and 1 water cooler from the designer

     

    Tools that help

     

    IR camera (even a £25 IR thermometer can help but a decent resolution camera is much better).

    Logic analyser

    A fast enough decent scope - if the scope you are using costs less than the salesman's car your management may have the wrong priorities. (Apply senss here - if you are debugging an Arduino shield this may not be necessary.)

    A good DMM (6.5 digits with good low voltage DC - so you can look at voltage drops on traces - Keysight or Keithley (see above)).

    Wiltrout special non slip probes on the DMM (really does help - if you boss won't pay for these start looking for another job).

    Decent bench power supply - if the supply screws up you'll blow the board, Keysight are nice, AimTTi are nice too and cheaper.

     

    Most Important Tool

     

    Your brain + 10000 hours of experience

     

    Second most important tool

     

    The second 10000 hours of experience..

     

    MK

  • in reply to michaelkellett

    Hi Michael,

     

    I do not often print the replies to posts but your reply was an exception. It was only after I printed it and reread it on paper that I caught the reference to the Non-Slip probes. I have never had to bring up a board any bigger than a small prototype but I have serviced many failed boards. The problems and solving techniques for failed boards seem to be very similar to the bring up of new boards. I always used a combination of experience and isolation. The experience is always expensive with respect to time and money. The isolation usually involved cutting traces and isolating components by desoldering one lead. It is also useful to always set the current limit on the power supply below a level that will do further damage. The non-slip probes are very useful as they allow me to easily probe through solder mask as well as place their position and not have to fight with slippage while I do other tests with my now free hand. I am tempted to insert a link here but anyone who is interested in my nonslip probe tip adapters can just search this site for Non-slip probes.

     

    John

Reply
  • in reply to michaelkellett

    Hi Michael,

     

    I do not often print the replies to posts but your reply was an exception. It was only after I printed it and reread it on paper that I caught the reference to the Non-Slip probes. I have never had to bring up a board any bigger than a small prototype but I have serviced many failed boards. The problems and solving techniques for failed boards seem to be very similar to the bring up of new boards. I always used a combination of experience and isolation. The experience is always expensive with respect to time and money. The isolation usually involved cutting traces and isolating components by desoldering one lead. It is also useful to always set the current limit on the power supply below a level that will do further damage. The non-slip probes are very useful as they allow me to easily probe through solder mask as well as place their position and not have to fight with slippage while I do other tests with my now free hand. I am tempted to insert a link here but anyone who is interested in my nonslip probe tip adapters can just search this site for Non-slip probes.

     

    John

Children
No Data