74LSA datasheet, 74LSA pdf, 74LSA data sheet, datasheet, data sheet, pdf, Texas Instruments, QUADRUPLE BUS BUFFERS WITH 3-STATE. Datasheet search engine for Electronic Components and Semiconductors. 74LSAN data sheet, alldatasheet, free, databook. 74LSAN parts, chips, ic, . Estate, Tai Po, N.T., Hong Kong. ◊. Page 6. This datasheet has been download from: Datasheets for electronics components.
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The purpose of this project was to design a digital LED clock influenced by the large clock on the building at Water Street in lower Manhattan. Jason has always wanted to create an homage to this clock since he finds the design inspiring. Jason and Eldar decided build a wall clock for their final project using the Water Street Clock design. They were motivated to create a functional piece of technology that adds datashet, vibrance, and time to any room.
The clock takes input from three Push-Down Buttons that select the mode of operation: Time, Date, and Temperature. The WWVB signal is transmitted one bit per second, taking 60 seconds to send the current time of day and date within a century.
Information is encoded using amplitude modulation with the following scheme: If power is reduced for one-fifth of a second 0.
If power 74ls125ann reduced for one-half of a second 0. If power is reduced for four-fifths of a second 0. Markers are sent during seconds 0, 9, 19, 29, 39, 49 and 59 of each whole packet. The start of the second of two consecutive markers indicates the top of the minute, and serves as the on-time marker for the next frame of time code. Markers are important to allow receivers to properly frame the time code.
Originally the focus of the project was on updating the clock using the WWVB signal relying catasheet hardware and its integration.
However, after more research and testing it was clear that the signal is quite unreliable due to the fact that it is a very weak signal and too much noise is injected into that bandwidth by our location on a highly technically advanced campus. At this point the focus was shifted to add more hardware in the form of an oscillator – which dramatically improved the accuracy of timekeeping and nearly eliminated the need for updating using WWVB.
The updates can now be also provided by an Arduino that sends the correct time to the PIC Additionally, since the project was inspired by a piece of visual art, we put in extra effort in making it aesthetically pleasing, e. DotStar LED strips were chosen as opposed to the NeoPixels, because they were easier to program, had better documentation, though they were more expensive. Additionally their implementation was complicated due to having to solder them with short wires having researched possible problems with using longer wires between cut strips.
No existing copyrights or trademarks or patents were found similar to our design. The digital clock on the building at Water Street was designed by Rudolph de Harak, an Datwsheet modern designer who worked in numerous mediums. High Level Block 47ls125an We chose this part because it is the only WWVB receiver currently available on the market.
The receiver is attached to a mm ferrite core antenna.
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DotStar LED strips were purchased from adafruit to light all the number of clock. The other reason we decided to use the DotStars was for their simple and reliable communication protocol via SPI. For our implementation the clock numbers were displayed on the face of the clock ordered from left to write, top to bottom, wrapping around from the end of right row to the beginning of left.
In order to wrap the LED strip, however, we couldn’t have long wires stretching across, and therefore, wrapped the LED strip around alternating sides of the box, see table below.
Clock Number in redLED number in blue: However, our implementation was more scalable than creating a table and saving it as a constant. We created functions to go from hours and minutes to LED location using modular arithmetic.
Thus, if this project were implemented with more LEDs, we could easily extend our functions to address the additional LEDs added to the matrix.
The DotStar strips were driven and powered by 5 V. Powering them was not an issue since all our other components also used 5 V. Voltage Level Translator 3. This specific value is convenient because 74ls125am is exactly and makes a 16 bit timer overflow exactly once a second.
We decided to not use a voltage divider or level shifter to guarantee the fastest time. In our project, nearly all devices use 5 V power. We purchased datasheeh 25W single output power supply made by Mean Well. We decided to use a 25 W power supply to give provide a maximum of datadheet A of current to power DotStar strip, which can pull a maximum of 4.
When designing our project, we wanted to add functionality in addition to time keeping. We settled on temperature because it is very easy to display room temperature in degrees celsius using the minute boxes. We used a LM35 analog temperature sensor to read ambient temperature. The housing was built out of a combination of plywood sheets and softwood planks.
The sides of the frame were half inch datashdet pieces of softwood, drilled on the bottom to hold the power supply in place, and on the left for the V AC chord path. The LED strips were hot-glued to the back face. A housing was created for each separate LED light in order to prevent light leaking into other numbers when diffusing onto the face. The rips were fitted in to house 74l125an lights and hot-glued in place.
The WWVB transmits data by datsaheet an amplitude modulated signal. The length of time the pulse is low determines the value 74,s125an the symbol being transmitted. We use an input capture module to trigger on the first falling edge and then on every edge after. The input capture begins on a 74lx125an edge because the length of a WWVB pulse is determined by the time the signal is at dB, which in our case is a digital low value. We set up an interrupt service routine that records the time for a falling 74ls1225an the first signal that causes the input capture to dstasheet and store sit into an integer, capture1.
The input capture will then wait until it sees the next edge which will be a rising edge and it records the current time and stores it into another integer, capture2. Additionally, increment counter that keeps track of symbol number in the current transmission. Several flags are also set here. For the falling edge we set ready to 0, indicating that time is not ready to be change.
When it receives the rising edge, ready is back to 1. In the timer thread, the 74la125an symbol and time can only be set when ready is 1. The input capture module is not able to determine whether the edge it is capturing on is high or low, therefore we set a bit back and forth to indicate which type of edge is next.
This is possible because we defined the first trigger to be on a falling edge. The input capture is very useful for calculating the time of pulses small pulses 74ls125ab the internal timers. If it does, overflow while decoding pulses, that pulse will be an error, and the Frame will need to restart. The timer thread is the heart of the entire program.
200 Water Street WWVB Clock
It begins by checking to see if the input capture has triggered twice, starting with a falling edge followed by a rising edge. The symbols are then stored into an integer. If a marker symbol is received, we check if the previous symbol was also a marker, which indicates the start of the next frame.
The yellow seconds indicator will begin to run, and it can be used as a countdown to when the entire dataframe will be received and the proper time and date are set.
We use 60 individuals case statements to based on the symbol number to decode time. For example, bits 12, 13, 15, 16, 17 and 18 in the frame are used for the hour values, 20, 10, 8, 4, 2 and 1 respectively bit 14 is left at 0. If the sequence is:.
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The function begins by converting the day of the year value to month and day values. Next, we call RtccSetTimeDate tm. The final part of the thread is case statement based the on the mode of operation time, date, or temperature.
Then each LED has its own data frame where the first 3 bits are 1, followed by a 5 bit value for the intensity level, then a 74ps125an bit value for blue, green, and red. Below is a visual representation of the protocol.
Next we do calculate which LEDs are the hour, minute and second and write a unique color value to each of them, while giving the other LEDs a different daatsheet. The LED for month is set the same way that hour is set and day the same way minute is set. We black out numbers 00 and since those are not possible dates. The LED for temperature is then set the same way same way that minute and day are. It is able to keep accurate time using an external Without the external oscillator, RTCC would need to use the internal oscillator which is not very accurate add spec?
User input is received via 3 buttons that are connected to the Small Dwtasheet Board. Every 30 milliseconds the buttons were polled to assess whether they had been pressed. The 74ls125am were set as digital inputs. Values from the previous poll were also kept to implement the following logic: The debounce functionality ended up being more robust than necessary as only the button presses were used to switch between the three different modes. Without the external oscillator, RTCC would need to use the internal oscillator which is not very accurate.
The RTCC periferal is initialized in the main function. The main function was used to set up the peripherals and threads 774ls125an were used and described above. The SPI was set up for channel 2 and configured to send 32 bit values The SPI clock speed is divided by 16 to give small relative rise and fall times after the signal is level shifted to 5 V. After datashwet for over four and half weeks to receive the WWVB receiver, it finally arrived.
Unfortunately, we had tremendous difficulty using it and were unable to pick up any trace of a signal in Phillips Hall. Since the deadline was approaching, we decided to use an arduino board to simulate the WWVB signal. We found code online 11 to do this. The arduino code sends a datashete clear pulse modulated signal, that PIC has not trouble decoding. From a black box perspective, 74ls125aj signal from the arduino and the signal from the WWVB receiver look totally identical.