The creation course of
Each venture/product has to start out with an concept, however going from that preliminary step all the way in which to a functioning prototype generally is a very intimidating course of to navigate, particularly for newcomers. As a option to helper make clear what must occur when taking the leap from concept to tangible product, element14 Presents host Clem Mayer undertook a venture to construct his personal USB card reader with comparatively frequent elements 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 usually take the type of already current merchandise and imagining the methods wherein they may very well be improved. Mayer’s supply of inspiration was his previous USB/SD card hub that will continually disconnect because of defective connectors and was troublesome to make use of because of 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 embody a full-size SD card for ease-of-use.
The PCB and enclosures
In keeping with Mayer, it’s a smart concept to include current elements right into a design and presumably use separate ICs for numerous duties relatively than monolithic ones, not less than initially, to get rid of 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 supplied by the exterior micro USB port, two USB-C ports for information and energy, and twin ESD safety circuits for future use.
Since dependable 3D-printed enclosures generally is a problem to each design and fabricate, Mayer factors out how there’s already giant ecosystem of pre-made enclosures obtainable. With the sizes identified upfront 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 because 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 because of, once more, improper reflowing because of too many close by heatsinks.
The PCB with a number of 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 essential 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!
