Once the microcontroller is set up, it is put into "sleep" mode. Code listings are also provided in pdf form if you just want to look at the code without installing Code Composer Studio. The attached file main.cfg contains the Grace setup, and main.c is the C source code. The reason is that I used a plug-in tool called GRACE to configure the peripherals, and this tool was dropped in later versions. I'm still using a quite old version of Code Composer Studio, Version 5.0. There are other Instructables showing how to use the MSP 430 LaunchPad with TI's supplied Code Composer Studio to develop code, so I will not duplicate that here. A few components such as the transistor drivers were add via a breadboard during circuit and software development. The LaunchPad connects to a host Windows computer via USB. The software was developed using an inexpensive MSP 430 LaunchPad development kit from Texas Instruments. The LED lights red with one port high and one low green with the port levels reversed. It is connected to two output ports of the microcontroller. The current pulse is typically 25 mS long.Ī bicolor LED provides a visual signal to help set up the clock. An output port drives a transistor pair that injects current into the coil. When the voltage exceeds a threshold, it "wakes up" the microcontroller. This voltage is fed into a comparator on the microcontroller. A simple filter limits the voltage of the signal from the coil when the magnet swings by. When the magnet passes the coil, it induces a negative then a positive current and voltage. It is wound with about 100 feet of 32 gauge magnet wire, yielding a resistance of about 50 ohms. The nylon parts came from my local Ace hardware. The coil is wound on a bobbin made up of two 1.25" nylon washers with a 1/2" long x 1/4" diameter nylon post glued to the washers. The regulator has a very low quiescent current.Ī single coil is used to detect the magnet passing by and to repel it. A 3.3 volt voltage regulator supplies the microcontroller. The electronics are powered by four D cells supplying 6 volts. A 32.768 kHz watch crystal provides a timebase for the microcontroller. It is a low-power device, - in fact, most of the time it is in "sleep" mode, drawing virtually no power. The heart of the electronics for this clock is a Texas Instruments MSP430 microcontroller. A hardware kit of all the non-wood parts, including the electronics, is also available at. (Sorry Carvewright uses a proprietary file format no files are available for other CNC machines). Here is a video on the design and construction of the clock: Synchronicityįiles are available to machine the wood parts of this clock on a Carvewright CNC. My circuit is powered by 4 D cells, which will operate the clock for up to three months. I wanted my clock to be accurate, so I use a microcontroller in my electromagnetic pendulum drive so that the clock keeps perfect time. Wood expands and contracts with changes in temperature and humidity. Often times wood clocks of this type are not very accurate. This triggers electronics to put a pulse of current into the coil (or a second coil) and repel the magnet, giving the pendulum a push and powering the clock. As the magnet passes the coil, it induces a current in the coil. The pendulum contains a rare earth magnet which passes by a coil or two. Some designers use an electromagnetic pendulum to drive their clocks. I wanted to build a wood gear clock that did not require that frequent winding. These clocks need to be wound periodically, as often as every day. Many wood gear clocks are driven by weights. Synchronicity is a unique exposed wood gear pendulum wall clock, with a combination of old and new tech.
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