As you might guess I got tired of putting together the "VUSB circuitry" so I put it on perfboard. I briefly mentioned the prototype it in #Pro Trinket USB Keyboard in this log.
I didn't quite like the female headers and matching USB cable so when I had some space on a PCB order I designed a better board for it.
Once I had this nicer version of the "VUSB circuit" board there wasn't really a point in keeping all the other duplicates of the board except that it's easy to modify into a generic breakout: just short the pads of the 68Ω resistors and leave the other pads unpopulated.
It can also double as a simple breadboard power supply by feeding the power rails via the PWR thingy. Since the complete bottom layer was unused in v1 I elaborated on the idea of using it as power supply by putting footprints for a voltage regulator on the bottom in v2.
Update:
Added v3 with minor redesign to supersede v2. Now it can act as a power supply with the following modes:
- Supply rail and Vcc pin (called VDD in schematic, labeled Vcc on board... sry) with 5V directly from USB (regulator not populated, short all 3 pads of solder jumper)
- Supply regulator with 5V from USB which in turn supplies rail and Vcc pin (short center and top pads [boad view]/Vrail and Vdd pads [schematic])
- Supply regulator from rail and get regulated voltage on Vcc pin (short center and bottom pad/Vrail and Vbus pads)
I'm not sure how useful the last mode is going to be, considering the size of the board and redundant pins.
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