11/18/2016 at 11:08 •
When it comes to mass production, it's best fit to design the whole board with discrete components rather than buying individual components, assembling and integrating them. It simply adds to the cost as well as space. Under Adafruit's courtesy, I have made a few changes with some components and added some design notes. The OLED module is pretty straight forward apart from the bidirectional logic level shifter. You can find more information about it in the following pdf: http://www.nxp.com/documents/application_note/AN10441.pdf
Refer the following schematic for the same:
09/08/2016 at 09:44 •
Once the breadboard view of the controller was developed, I moved onto designing and developing the USB hub controller on Eagle 7.6 Lite. This software is a very handy tool for makers and hobbyists as it provides free license for up to 2 layers. This is more than enough for our project. There are other softwares which serves the purpose like OrCAD Lite. There is no time limit for this version but is limited by the complexity of the design like a design with more than 90 nets cannot be saved etc. I have been working on a custom library for the usb controller. The differential USB data lines require high speed TVS (Transient Voltage Suppressor) ESD(Electro Static Discharge) protection diodes. The TI TPD4E1U06 serves exactly this purpose. Hence, the REV A usb hub would look a little ugly due to the large number of TVS diodes. I have uploaded the REV A schematics which would be very shortly revised with the custom library part.
09/07/2016 at 12:16 •
Initially I started working with the USB Hub. I really have no clue why I started with it. But yeah, who knows. Any ways, before going to the actual schematics, I just thought to generate the breadboard view of the board. But yeah, it really doesn’t give feel of the hub. But yes, it does show how such a circuit rigged on the breadboard (perf board) would look like. I should tell you that there is absolutely no chance the board would do its functionality when rigged on the perf board as there are some considerations to be taken care about when laying out the differential signals of the USB upstream and downstream ports. Guys, just take a look of the Fritzing developed perf board view of the USB hub.