![]() It would be much more precise to monitor the 60 Hz from the electric utility for the time base (refer to the sidebar). I then considered that I would be running the microcontroller with its internal oscillator that probably wasn’t all that stable the clock wouldn’t keep accurate time. I decided to include another LED for a PM indicator, so an alarm that was set for say, 6:00 AM wouldn’t sound at 6:00 PM. Plus, one more LED to indicate when the alarm was turned on would be necessary. Now I needed to add a buzzer for the alarm and probably a couple more pushbuttons to set it. However, my professor insisted I add an alarm feature. It was an 18-pin controller with 16 I/O lines - the exact number of I/O lines that I needed. I had been playing around with Microchip products for a number of years, so I chose the PIC16F627A. I had already picked out the microcontroller that I wanted to use. Two more I/O pins would be used to read two pushbuttons used for setting the clock. I figured I could drive the LEDs with 14 I/O pins using Charlieplexing (more on that later). I wanted to use a microcontroller with the lowest pin count possible. The clock never became much more than an idea in the back of my mind until I decided to make it for my Senior Project to complete my Electrical Engineering degree. I had envisioned using both T1 (3 mm) and T1-3/4 (5 mm) LEDs the larger LEDs would be used every fifth position at each hour mark. Although only 12 LEDs would be needed to display hours, I thought it would be more symmetrical if I used 60 and advanced it every 12 minutes. The outer circle of LEDs would be for representing seconds, the middle circle for minutes, and the inner circle for hours. It would have three circles of 60 LEDs each. I immediately thought that a good use of this technique would be to make a clock. Here you can download full pdf version of manual, it may contain additional safety instructions, warranty information, FCC rules, etc.Several years ago, I read about a technique called Charlieplexing where you can control a large number of LEDs individually with a relatively small number of I/O lines. The LED next to the programmed mode will illuminate. To view the program that is currently set when the timer is not providing power to the attached devices, press the "SET" button.The LED next to the programmed mode will glow red when the timer programming is activated and power is being provided to attached devices.When set to "ON", the timer will provide continual power to attached devices until the timer is switched to "OFF", or to any of the other Operating Modes.Headlights, porch lights, street lamps and other external lighting sources will not interfere with the active timer program. Once programming activates at dusk in the 2hr, 4hr, 6hr, 8hr, 12hr or dusk-to-dawn mode, the program cycle will complete before the timer resets.The photocell is located above the "SET" button on the face of the timer. This timer operates using a light-sensitive photocell that senses when the environment is getting dark (dusk) or light (dawn).The timer will function outdoors when installed and operated as outlined in this manual. This timer is weather-resistant and rated for Outdoor Use.Plug the devices into the outlets on the bottom of the timer. After 5 seconds, LED will flash rapidly to confirm selection.Ģ Hrs - Power will turn on at dusk and remain on for 2 hoursĤ Hrs - Power will turn on at dusk and remain on for 4 hoursĦ Hrs - Power will turn on at dusk and remain on for 6 hoursĨ Hrs - Power will turn on at dusk and remain on for 8 hoursġ2 Hrs - Power will turn on at dusk and remain on for 12 hoursĭusk-Dawn - Power will turn on at dusk and remain on until dawn Press the "SET" button to cycle the LED's to the desired mode. Do not use extension cords to connect the timer to the power source. Use an outdoor-rated three-pronged grounded electrical outlet. Place the timer over the screw heads and push down to lock into place.Insert two #6 sheet metal screws (not included), leaving screw heads protruding 1/8 inch from the surface. ![]() Drill two 3/32 inch pilot holes where indicated on the mounting template.Temporarily secure the mounting template to the flat surface where the timer is to be mounted.Create a mounting template by placing a sheet of paper over the back of the timer and punching holes through the paper where the mounting holes are located on the timer.For a more secure mounting, use the two MOUNTING HOLES on the back of the timer.Using a screw or hook (not included), secure the MOUNTING TAB at the top of the timer to a wall or post.INSTALL TIMER to a vertical a flat surface close to a properly installed outdoor-rated grounded receptacle.
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