Description: The NTE is an 8-bit parallel-in or serial-in, serial-out shift register in a Lead plastic DIP type package having the complexity of 4 — 28 December Product data sheet .. supply current VI = VCC or GND; IO = 0 A;. VCC = V. -. -. -. -. μA. CI input capacitance. -. description. The ‘ and ‘LSA are 8-bit serial shift registers that shift the data in the direction of QA toward QH when clocked. Parallel-in access to.
|Published (Last):||18 January 2014|
|PDF File Size:||9.10 Mb|
|ePub File Size:||16.95 Mb|
|Price:||Free* [*Free Regsitration Required]|
This is a way to convert data from a parallel format to a serial format. By parallel format we mean that the datassheet bits are present simultaneously on individual wires, one for each data bit as shown below. A stage consists of a type D Flip-Flop for storage, and an AND-OR selector to determine whether data will load in parallel, or datasueet stored data to the right. In general, these elements will be replicated for the number of stages required.
We show three stages due to space limitations. Four, eight or sixteen bits is normal for real parts. At the next positive going clock edge, the data will be clocked from D to Q of the three FFs. The type of parallel load just described, where the data loads on a clock pulse is known as synchronous load because the loading of data is synchronized to the clock.
This needs to be differentiated from asynchronous load where loading is controlled by the preset and clear pins of the Flip-Flops which does not require the datssheet.
Only one of these id methods is used within an individual device, the synchronous load being more common in newer devices. Clock pulses will cause data to be right shifted out to SO on successive pulses. The waveforms below show both parallel loading datadheet three bits of data and serial shifting of this data.
What we previously described with words for parallel loading and shifting is now set down as waveforms above. It needs to be low a short time before and after the clock pulse due to setup and hold requirements.
It is datasheet wider than it has to be. Though, with synchronous logic it is convenient to make it wide.
The datasheft factor is that it needs to be low around clock time t 1 to enable parallel loading of the data by the clock. This is the parallel loading of the data synchronous with the clock. It is either shifted into another integrated circuit, or lost if there is nothing connected to SO. The 1 at Q A is shifted into Q B.
The last data bit is shifted out to an external integrated iv if it exists. After t 4 all data from the parallel load is gone. At clock t 5 we show the shifting in of a data 1 present on the SI, serial input.
Why provide SI and SO pins on a shift register? These connections allow us to cascade shift register stages to provide large shifters than available in a single IC Integrated Circuit package.
They also allow serial connections to and from other ICs like microprocessors. For complete device data sheets follow these the links. Let us note the minor changes to our figure above.
First of all, there are 8-stages. We only show three. All 8-stages are shown on the data sheet available datashset the link above. The manufacturer labels the data inputs A, B, C, and so on to H.
It is abbreviated from our previous terminology, but works the same: Once we know how the part operates, it is convenient to hide the details within a symbol. There are many general forms of symbols. The advantage of the ANSI symbol is that the labels provide hints about how the part operates.
Shift Registers: Parallel-in, Serial-out (PISO) Conversion
There is a reset indicted by R. There are three control signals: The clock has two functions. First, C3 for shifting parallel data wherever a prefix of 3 appears.
In this case, we can conclude that the parallel data is loaded synchronously with the clock C3. The upper stage at A is a wider block than the others to accommodate the input SER. Thus, we expect to clock in data at SER when shifting as opposed to parallel loading. The long triangle at the output indicates a clock. If there was a bubble with the arrow this would have indicated shift on negative clock edge high to low.
Since there is no bubble with the clock arrow, the register shifts on the positive low to high transition clock edge. See the link at the beginning of this section the for the full diagram. We have not looked at asynchronous loading of data up to this point.
First of all, the loading is accomplished by application of appropriate signals to the Set preset and Reset clear inputs of the Flip-Flops.
IC datasheet & applicatoin notes – Datasheet Archive
There would dayasheet no possibility of loading the FFs. Since none of this required the clock, the loading is asynchronous with respect to the clock. We use an asynchronous loading shift register 71466 we cannot wait for a clock to parallel load data, or if it is inconvenient to generate a single clock pulse.
The only difference in feeding a data 0 to parallel input A is that it inverts to a 1 out of the upper gate releasing Set. SRG8 says 8-stage shifter. The arrow after C2 indicates shifting right or down. SER input is a function of the clock as indicated by internal label 2D. Pins P3 to P7 are understood to have the smae internal 2,3 prefix labels as P2 and P8. The CDB is a similar part except for asynchronous parallel loading of data as implied by the lack of any 2 prefix in the data label 1D for pins P1, P2, to P8.
Of course, prefix 2 in label 2D at input SER says that data is clocked into this pin. The bubble within the clock arrow indicates that activity is on the negative high to low transition clock edge. Before the slash, C4 indicates control of anything with a prefix of 4. The long arrow indicates shift right down. Moving down below the control section to the data section, we have external inputs P0-P15pins The prefix 3,4 of internal label 3,4D indicates that M3 and the clock C4 control loading of parallel data.
The D stands for Data. This label is assumed to apply to all the parallel inputs, though not explicitly written out. All other stages shift right down at clock time. Moving to the bottom of the symbol, the triangle pointing right indicates a buffer between Q and the output pin. The Triangle pointing down indicates a tri-state device. The internal datashete of the SN74LS and a table summarizing the operation of the control signals is available in the link in the bullet list, top of section.
The Alarm above is controlled by a remote keypad. Thus, we read nine key switches with four wires. How many wires would be required if we had to run a circuit for each 47166 the nine keys? Or, we may have used most of the pins on an pin package. We may want to reduce the number of wires running around a circuit board, machine, vehicle, or building.
This will increase the reliability of our system. It has been reported that manufacturers who have reduced the number 741666 wires in an automobile produce a more reliable product.
In any event, only three microprocessor pins are required to read in 8-bits of data from the switches in the figure above. We have chosen an asynchronous loading device, the CDB because it is easier to control the loading of data without having to generate a single parallel load clock. Any switch closures will apply logic 0 s to the corresponding parallel inputs.
The microprocessor generates shift pulses and reads a data bit for each of the 8-bits.
Shift Registers: Parallel-in, Serial-out (PISO) Conversion | Shift Registers | Electronics Textbook
This process may be performed totally with software, or larger microprocessors may have one or more serial interfaces to do the task more quickly with hardware. This is repeated for all 8-bits. The SER line of the shift register may be driven by another identical CDB circuit if more switch contacts need to be read.
In which case, the microprocessor generates shift pulses. More likely, it will be driven by something else compatible with this serial data format, for example, an analog to digital converter, a temperature sensor, a keyboard scanner, a serial read-only memory.
As for the switch closures, they may be limit switches on the carriage of a machine, an over-temperature sensor, a magnetic reed switch, a door or window switch, an air or water pressure switch, or a solid state optical interrupter.
Published under the terms and conditions of the Design Science License. You May Also Like: A practical introduction to quantifying perceived light intensity. But you don’t have to buy one- you can convert an old mechanical thermostat Quote of the day.