This project implements a USB device which provides a real-time clock for the purpose of time-stamping events in an non-networked embedded computer environment. For embedded applications where a periodic time-stamp is required (such as entry-system logs, configuration audit logs, etc. ) it is necessary to have a fairly accurate real-time clock (bet
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ter than that typically provided by a PC`s motherboard) to generate time-stamps in logging and audit trails. Furthermore, it is preferable to have a method of confirming that the log/audit files have not been tampered with in anyway. The secure USB time-stamp device solves many of these issues in a very small form factor using minimal components. The device logs the time at which the clock was last updated and (if requested by the USB host) the time when it last served a time-stamp. This allows the host application to examine it`s own logs and compare them to the time values stored by the device (to detect when logs have been altered). The device stores the last time setting and the last logged time-stamp in the PIC`s non-volatile EEPROM memory which can hold the data for up to 40 years without battery backup. The SUTS device is powered by a PIC18F2550 microcontroller which provides an on-board USB interface as well as the required SPI serial interface to the DS1302 real-time clock chip. To prevent loss of time setting when powered off or disconnected the DS1302 is backed up by a 0. 047F super-capacitor. A super-capacitor was chosen (rather than a lithium cell) since it is harder to remove (preventing a casual or deliberate reset of the time), charges very fast (less than 5 minutes from empty to fully-charged) and is capable of powering the RTC for around 90 hours without losing time. Furthermore, the super-cap has a...
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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