If you are an Embedded engineer or Manager or a company who want to build an embedded hardware product, it is very important for you to understand how the embedded hardware development process looks like.
What all steps are involved in the embedded hardware development.
I am working as a consultant with various companies and help them build embedded hardware products which involves hardware development and/or firmware development depending on the scope of work.
And, the steps mentioned below are what I following in the development process so don’t think its just a theoretical knowledge but practical steps.
In this blog, I will focus on the embedded hardware development, will share steps involved in firmware development in another blog.
Steps involved in Embedded Hardware Development
(each stage involves multiple review internally with in the team, this may include engineers from customers team as well)
- Technical Specification: first thing first, the technical requirement specification is very important. We should have a clear document which states what is required to be developed in the hardware. This typically includes a block diagram to give a bird eye view and details about all the features. More details on how to write a good technical specification document of an embedded product.
- Architecture of the hardware: This is where a hardware engineer defines how divide the who hardware into different blocks and how these different hardware blocks will be connected to each other.
- Component Selection: In order to move forward, hardware engineer need to find out main components for each hardware sub block. For example if a USB to UART interface is required in order to connect the product to PC, engineer to figure out which USB to UART IC will be used. Similarly if any sensors are involved, need to find which IC to be used. IF any wireless connectivity is required, you need figure out which module or wireless SoC to be used. Read this article for detailed understanding on how to select electronic components.
- Electronic Circuit Design: Once the main architecture design is ready and major components are selected, hardware engineers need to design the circuit around each chip for each block. For example, we talked about USB to UART interface, which chip to be used but then what all other components(passives) are required to complete the circuit. Similarly engineers need to design circuit for all other interfaces in the hardware.
- Schematic Capture: Once circuit design is completed, Schematic stage comes where engineer design the whole circuit using an EDA tool like Altium Designer, Orcad, KiCAD, etc. This involved schematic symbol creation, designing the schematic. Multi-sheet schematics are preferred in order have a good readability. One should also add more details in each section which helps gain understand about the circuit. For example: Typical current consumption of the IC, alternate parts, Label each section on a schematic sheet, etc.
- BOM Cost Analysis: At this stage you know which all components are used in the hardware, so bill of material cost is calculated to review if cost of the hardware is as per expectation or any modifications are required to adjust the BOM cost. This is an important step before building further.
- Compliance consideration: EMI EMC, Environmental considerations are reviewed in this stage and in any improvements required in the schematic are done.
- Test Procedure: In this stage engineering team define what all tests need to be carried out to validate the hardware and what all instruments will be required to do so.
- PCB Design: in this stage hardware engineer, designs the PCB which includes PCB footprint creation, components placement and layout.
- 3D Model / Mechanical Review: After PCB design is complete, the 3D model is generated and a review is done from mechanical fitment point of view, this allow the team to check if hardware fits well in the enclosure, accessibility is there for assembly, user access to different interface.
- Generate Manufacturing Files: Once the mechanical review is done and design gets approved. Manufacturing files are generate to be sent to vendors for PCB manufacturing nd PCB assembly. Main files generated are:
- Gerber Files
- Drill Files
- Pick and Place File
- Bill Of Material
- Assembly Drawing
- PCB stack-up details
- Any PCB Fab instructions, if required
- Any PCB assembly instructions, if required
- Send Files to Vendor for PCB, PCBA: We send the files to vendor for Prototype version 1 manufacturing. This stage generally take 3-4 weeks of time. During this time, team will setup the hardware testing jig (manual or automatic), take support from firmware team to build test firmware which will be required to test the hardware.
- Board Bring Up/Testing/Debug: Once you get the PCB prototype version 1 from the vendor, you need visually inspect it and check if everything is done as requested and the start testing the hardware block by block. Generally, 1st boards are tested by powering one block at a time as there are chance some design mistake is there, if we power full board we will end up loosing the whole hardware that why block wise power up of the circuit and testing is done. If any issues are found during testing, those are debugged and engineer will try to fix the issue with some workarounds like jumpers, using external components or hardware. Many times this stage also involved 3-4 weeks of testing to ensure prototype version 1 works well and issues do not go to next prototype version.
- Review Points from Prototype Version 1: One the testing is completed, engineers know what all issue are there in the board, those are noted down and discussed with the team to take a decision which all need to fixed and which are not that important. Issues like extra label on board, repositioning of any connector for ease of testing etc. are also noted not just the design issue. The whole idea of this stage it find all points which needs to be improved which will reduce the effort in testing, assembly, repair, etc. In many cases this stage also involved compliance testing in-house or in an external Lab.
- Delta Design changes: After review of prototype version 1 testing is done considering all review points, design changes are done to improve the design further. This stage aims to make sure Prototype version 2 is good enough to go for initial 100-500 units pilot lot production and field trials. Changes may involved in Component changes, changes in Schematic, PCB. Design cycles repeats for prototype version 2 from point 5 to 13.
- Ready for Pilot: In 99% of the cases 2 iterations are good enough but if design is still not ready due to technical issues, may need further iterations. Cycle repeats from 5 to 11 for each iteration.
Above details, gives a good overview of what happens in a typical embedded hardware development cycle, a lot more goes in the process which is not covered here for the sake of simplifying it and making it easy for everyone to understand at high level.
I hope you have understood the steps involved in hardware development of a product.
If you need help in embedded product development, I help companies build successful and reliable products.
If you have any feedback, you can share in the comments section or you can also contact me directly.
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