How to Convert USB to Serial TTL Level Signals

If you’re designing a device that spends most or all of it’s time connected to a PC through a USB port, it is probably best to design USB connectivity right into the device.  However, if the device only needs to be connected occasionally to change settings or download data logs, it might be convenient to use a separate adapter that translates USB protocol to TTL level asynchronus serial signals that talk to the microcontroller’s UART.  Also, if you’re a hobbyist, you may not want to spend a lot of time understanding the details of USB interfacing hardware and protocols.  I recently stumbled upon an adapter that makes this easy.   

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Simple Thermal Heat Transfer Finite Element Analysis in Excel 2007

While some free finite element analysis software is available, the engineer or student can learn a lot about how FEA works by constructing a simple model from scratch in a commonly available spreadsheet program such as Excel.  The technique presented here can simulate a two dimensional flat plate of uniform thickness.  Each boundary element can be an arbitrary fixed-temperature or insulated.  The resultant temperature of each active element is iteratively calculated by simply averaging the temperatures of the adjacent cells.  Read the rest of this entry »