This is designed to be used as a programmable LED display for numerous applications. I also wanted to include some additional features so that the display can be used instantly. The display uses a sure 8 x 32 LED dot matrix. This is interfaced to a Xino (or Arduino ). The display works really nicely but I wanted a few more features for this project. So I added 2 x buttons for any user input, a temperature sensor,
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a buzzer, a wireless link and a real time clock. This is a post about using real time clocks. Real time clocks are designed to very accurately measure time. They use an external oscillator (in this case a watch crystal running at 32. 768kHz). While micro-controllers are very good at performing many functions, unless very careful programming is used then it is difficult to accurately keep track of time. Lots of different commands use varying lengths of time to complete hence using the micro-controller instructions to keep track of time is quite difficult to implement. Certainly it is very difficult with the Arduino, as it is not designed to easily use the interrupts (which is how you can get very accurate timing). It is very easy to add a commercial real time clock chip onto a project and that will ensure very accurate timings are performed. I used the PCF8583 from Dallas Semiconductor. This is a relatively cheap (around £2) real time clock which uses the I2C serial data transfer method. It also has an additional 240 8-bit ram locations, which could be useful. As usual in these interconnected days, some one has already released the code required to easily talk to the PCF8583. It is available here. It was developed by Joe Robertson. To keep the time when switched off, a back-up battery must be used. This can be any battery from 1V to 6V. I used a 3V CR2032 coin cell. You must be careful to ensure that the battery does not...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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