Greetings, and welcome to another (although belated) post. Work, studies and life have kept me from the page, hopefully this post marks a turnaround. Today, detail on program flow, microprocessor choice and other tidbits.
Firstly, I have completed a flow of operations for automatic generator start.MainsMonitorAndGen
I have decided to use the Texas Instruments MSP430 series micro-controller. They are relatively cheap, appropriately fast, easy to get working and need next to no extra circuitry to have them working in the application. They have internal timers/oscillators, and depending on the version of chip, have numerous analogue/digital converters, and up to 16 GPIO pins. I2C and SPI are supported natively on many of the chips. The launchpad is an integrated programmer/testbed that makes learning and development easy, while providing a platform to program each chip as needed before placing them into circuit. Once programmed, the chip can simply be soldered into its appropriate circuit board.
Right now I am using the g2553 as that’s what it came with, but if I find that I can get away with slower clocks or lower ram, then I might select another, cheaper chip for the application.
A couple of items to note so far in the circuit design is that I have so far worked out all mains triggering, valve actuation and power switching form a logical point of view, however the final circuits still need to be drawn up. Most relays will be high voltage capable latching relays that will be able to switch current reliably. The ones I have found have massive isolation at 15Kv, and so come at a bit of a price. All electronic circuit isolation will be by the way of opto-isolator chips, which will utilize physical board separation as well as fusing in all wires to ensure that there is very little chance of sending mains into the controllers.
I still also need to figure out how the MCP will know when generator has started, but I have a few ideas and still need to test them out. At this point it looks like there might be 3 micrcontrollers:
- Master controller with mains sensing. This unit will command generator start and switch all relays on the mains.
- Generator controller, starts and monitors generator stats including temperatures.
- Reporting controller gets serial output from the master and provides output in terms of an LED display.
There is however, scope to add more if it seems appropriate. Unfortunately I have allowed the scope to creep a little as I have decided I
needed wanted more functionality. The most notable iten here is a UPS powered by those crazy dudes of the battery world, the venerable 18650 Lithium Ion cell. Wish me luck.
Obviously there is a lot to do in this project and life is a re-occurring event right now, but hopefully it wont be weeks before the next post arrives.
So until next then, just build something…