BOARD BRING-UP

Board bring-up is the process of checking and validating a PCB assembly for the first time. The aim is to make sure that the board has been manufactured and assembled correctly and that all of the subsections of the design work as intended. This can be a nervous time for an electronics designer as it is a key proof point that many weeks or months of work has been successful.


Note that bring-up is not the same as validating an entire product or system – it is usually limited to validating the hardware. Writing firmware will likely be a part of the process, but only to the extent required to ensure the processor, its peripherals and external circuitry connected to them are working as expected.

Board Bring-up process.

1. Visual Inspection:
Print out assembly drawing with all the components and test points to have a quick reference during validation.
  • All the components are placed correctly.
  • All the PINs 1 are placed correctly.
  • There are no visible short circuits between PADS.
  • Are pads soldered with good quality?
  • All the components with defined polarity are placed correctly.
2. Impedance measurement on power rails
  • Go through all the power rails and measure the impedance between ground and power rail. These must not be a short circuit. Some power rails may have a low impedance starting from 100s of ohms. Refer to power tree to check is current consumption higher.
3. Plug In
  • Check voltage output of power supply (before connecting to the board)
  • Set power supply current limit properly (before connecting to the board)
  • Have connected the board with correct polarity?
  • Cover the board for first-time power up (in case something blows up) and switch the power ON
  • Monitor the maximum current, note if the current is changing or stable. (e.g. If it is increasing continuously, then something is wrong)
  • Check the component temperature with a contactless thermometer. Do not touch the circuit as it may damage some component due to ESD.
4. Measure the Power
  • Check all the power rails and cross verify with schematic/power tree voltage value. Note down the effect of tolerance, it might be helpful in finding bug later.
  • Measure noise/AC component on each power rail, find if more decoupling is required.
5. Measure oscillations
  • Check all the crystals and oscillators. If some of crystal are not starting, then the board may never boot.
6. Start the Play
  • if everything is working ok, load a basic firmware and start checking peripherals one by one. In this step, calibration of ADC and DAC can be performed, improve firmware reliability.
  • After basic check, upload full-fledged firmware and start checking more inter-related functions.
  • Based on the need for hardware, prepare the test cases and test setup to minimize human interferences, e.g. try to collect data automatically 
  • Update the firmware with every bug found and re-run the complete set of tests.

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