74LSN from Fairchild Semiconductor. Find the PDF Datasheet, Specifications and Distributor Information. 74LSN Datasheet, 74LSN PDF, 74LSN Data sheet, 74LSN manual, 74LSN pdf, 74LSN, datenblatt, Electronics 74LSN, alldatasheet. These 8-bit shift registers feature gated serial inputs and an asynchronous clear. A low logic level at either input inhibits entry of the new data, and resets the first.
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Negative seems to indicate source current, and positive sink current. See this answer to a previous topic, for more info.
The serial inputs pin 1 and 2 of the IC has a special purpose of resetting the above procedure in an interesting pattern. When the asker is sourcing more than the chip can do by more than a factor of 10, I’d look there first. Also, why does the scope only show 2Vpp in one picture? Thus exceeding operating conditions, all bets are off. James Magnus 55 7.
Hopefully you will get to see another article pretty soon, which will explain the practical utility of this wonderful IC. Thanks for all your advices and suggestions, have a nice day.
74LSN datasheet, 74LSN datasheets, manuals for 74LSN electornic semiconductor part
Hasn’t ever happened to me. You 7ls164n simply have a logic level compatibility issue between Pi and the LS inputs. Take a peek at the data sheet. For example if the pin — outs 1 and 2 are permanently connected to the positive supply and the reset pin is dwtasheet to the last output of the IC pin 13then, as discussed earlier, once all the outputs become high the last pin 13 instantly resets the whole circuit, shutting the whole array of outputs, and the cycle repeats.
You might even need to replace the shift register, but probably not.
74LS – 8-Bit Shift Register Ser In/Para Out
The whole output array, instead of shutting down all together, now starts receding sequentially one-next-to-the-other, until all of them are shut down to begin the cycle all over again. Or, the pulse has a ragged edge s and the is actually clocking several times.
You are probably getting multiple pulses instead of just one.
This chip can’t drive the kind of current you want it to. You have an unexplained 1V offset. Through a few of my previous articles I have tried to cover the working principles of a couple of versatile ICs like the and The whole output array, instead of shutting down all together, now starts receding sequentially one-next-to-the-other, until all of them are shut down to begin the cycle all over again. Looks pretty clean but you need to zoom way in to know for sure. Do you have an oscilloscope?
I use leds to see what happen. Now suppose if through a simple wiring pins 1 and 2 are configured in such a way that when the last pin 13 of the IC goes high while sequencing serially, it grounds the serial input 1 and 2. FiddyOhm Reading the datasheet here, I can’t find an issue with the logic levels. Introduction Through a few of my previous articles I have tried to cover the working principles of a couple of versatile ICs like the 74lz164n A Low power Schottky input typically sits at about 1.
What am I doing wrong? You should test with the FETs in place. Similarly the IC requires only an external clock signal to make its 74sl164n swing into action and produce interesting logic sequences. This opposite sequencing also takes place in accordance to the rising pulse of the input clocks. Sign up using Email and Password.
You likely have reflections on your clock line, causing it to be treated as multiple clock pulses. Email Required, but never shown. This opposite sequencing also takes place in accordance to the rising pulse of the input clocks. The thresholds are 0. Hopefully you will get to see another article pretty soon, which will explain the practical utility of this wonderful IC. Then I send a clock pulse from the Raspberry Pi go high for ms then go low. Better yet, JamesMagnus, you have a scope.
Home Questions Tags Users Unanswered. I took some photos of the scope, the first is the clock from dwtasheet GPIO without nothing and the second is the clock connected to the register. Just disconnect the LEDs and use the scope to check outputs. That’s pretty far fetched, given the frequencies involved. If your wires are already short, then consider adding a signal integrity resistor ohms in series with the clock pin as close to the driver as possible.
Referring to the figure on the left we see that externally it looks just like an ordinary pin dual in-line chip.
Unlike ordinary CMOS ICs which has also been discussed in many of my previous articlesthe above ICs are equipped with many different built-in features which may be accessed or activated by just applying the appropriate logic inputs or components to their relevant pin-outs.
74LS164 – 8-Bit Shift Register Ser In/Para Out
Sign up or log in Sign up using Google. Might be missing decoupling capacitors too. That’s a good guess, but the recent oscilloscope pictures posted after your answer looks pretty clean.
Finding out where that offset comes from should be the absolute first priority here. The serial inputs pin 1 and 2 of the IC has a special purpose of resetting the above procedure in an interesting pattern. When I power-on the circuit, all the LEDs are off. I resolved my problem. In real I will put mosfets to control a big led board. Similarly the IC requires only an external clock signal to make its outputs swing into action and produce interesting logic sequences.