Electronic – Websockets for Embedded Application

I haven't had much personal experience with RTOS's other than QNX (which is great on the whole but it's not cheap and I have had a really bad experience with a particular board vendor and QNX's we-don't-care attitude for systems other than their most common) which is too large for PICs and MSP430's.

Where you will benefit from an RTOS is in areas such as

• thread management/scheduling
• inter-thread communications + synchronization
• I/O on systems with stdin/stdout/stderr or serial ports or ethernet support or a filesystem (not an MSP430 or PIC for the most part, except for the serial ports)

For peripherals of a PIC or MSP430: for serial ports I'd use a ring buffer + interrupts... something I write once per system and just reuse; other peripherals I don't think you'd find much support from an RTOS, as they are so vendor-specific.

If you need timing that is rock-solid to the microsecond, an RTOS probably won't help -- RTOS's have bounded timing, but typically do have timing jitter in their scheduling due to context switching delays... QNX running on a PXA270 had jitter in the tens of microseconds typical, 100-200us maximum, so I wouldn't use it for stuff that has to run faster than about 100Hz or which needs timing much more accurate than about 500us. For that kind of stuff you probably will have to implement your own interrupt handling. Some RTOS's will play nicely with that, and others will make it a royal pain: your timing and their timing may not be able to coexist well.

If the timing/scheduling is not too complex, you may be better off using a well-designed state machine. I would highly recommend reading Practical Statecharts in C/C++ if you haven't already. We've used this approach in some of our projects where I work, and it's got some real advantages over traditional state machines for managing complexity.... which is really the only reason you need an RTOS.

There is more to schematics than just being able to "read" them.

To read them you may think you just need to understand what the symbols mean. Yes, that is an important part of it, like knowing what the letters of the English language mean. But you also need to understand how the components in the circuit work, and how they interrelate to each other (kind of like Grammar and Syntax).

To learn the symbols all you need is a list, like this one: http://www.kpsec.freeuk.com/symbol.htm

However, to understand what the components do and how they work you will need the following:

1. Knowledge and training of the basics - resistors, capacitors, transistors, inductors, etc.
2. Knowledge and training of how the more complex devices operate and interrelate - op-amps, microcontrollers, other specialist chips.
3. Data sheets for any components that are more complex than a simple resistor or capacitor (unless you require high tolerances in which case you may want data sheets even for those).

So it's not like learning to read another language, like say Japanese. It's learning the language and the culture and the history of the country.

Yes, there are often common themes in circuits, where you will see recurring schematic chunks - like the Darlington Pair, the Emitter Follower, etc, but even a common circuit chunk like that could operate completely differently in a different circuit.