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The creation course of
Each challenge/product has to begin with an concept, however going from that preliminary step all the way in which to a functioning prototype is usually a very intimidating course of to navigate, particularly for freshmen. As a strategy to helper make clear what must occur when taking the leap from concept to tangible product, element14 Presents host Clem Mayer undertook a challenge to construct his personal USB card reader with comparatively widespread parts and a DIY PCB design.
Discovering a product
Earlier than one may even discover an concept for one thing to construct, innovation and brainstorming can typically take the type of taking a look at already present merchandise and imagining the methods by which they may very well be improved. Mayer’s supply of inspiration was his outdated USB/SD card hub that may continuously disconnect as a consequence of defective connectors and was tough to make use of due to its non-ideal type issue. To iterate, he considered taking the USB hub concept, flattening the design into a skinny card form whereas including USB-C performance, and embrace a full-size SD card for ease-of-use.
The PCB and enclosures
In keeping with Mayer, it’s a clever concept to include present parts right into a design and probably use separate ICs for numerous duties reasonably than monolithic ones, a minimum of initially, to remove factors of failure. On this design, he went with a USB2640 USB hub + media controller IC from Microchip which mixes the USB performance and skill to learn/write SD playing cards right into a single chip. Along with this part, Mayer added an ESP32-C3 to regulate the quantity of present being offered by the exterior micro USB port, two USB-C ports for knowledge and energy, and twin ESD safety circuits for future use.
Since dependable 3D-printed enclosures is usually a problem to each design and fabricate, Mayer factors out how there may be already giant ecosystem of pre-made enclosures out there. With the sizes identified prematurely from their datasheets, PCBs may be designed to suit properly and customized face plates may be made for port openings and added safety.
Challenges with a proof of idea
After assembling his USB card reader circuit, Mayer plugged within the USB-C port to his PC and found nothing was being acknowledged as a result of the connector was not soldered correctly. After a fast repair, it nonetheless was not working, this time as a consequence of a lacking bias resistor. As soon as added, the media controller chip was lastly being enumerated by the OS, but the ESP32 chip was nonetheless not acknowledged as a consequence of, once more, improper reflowing due to too many close by heatsinks.
The PCB with just a few bodges added
Alternatives for enhancements
All of those issues and eventual options are a pure a part of the iterative design course of, and every lesson alongside the way in which results in a much better product in the long run. As Mayer emphasizes in his video, fastidiously studying the datasheet, double-checking footprints, and including loads of check factors are all vital steps to making sure issues work the primary time. For his subsequent iteration, Mayer plans to fall again to a earlier USB/media controller chip, SD card slot, and voltage regulation circuit since they’re extra acquainted.
To see extra about how this USB card reader was designed/constructed and the challenges alongside the way in which, you’ll be able to watch Mayer’s e14 Presents video under!
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