Shrnutí

The SN74HC165N is an 8-bit parallel-load shift register widely utilized in digital electronics to expand the number of digital inputs for microcontroller projects, particularly those involving Arduino development boards. It serves as a crucial component when additional input pins are needed beyond what the microcontroller can natively support. This device is particularly useful in applications that interface with multiple switches, sensors, or displays that require numerous pins

. The shift register operates by loading data from its parallel inputs and then serially shifting it out, thereby reducing the number of I/O pins required on the microcontroller. This process can be managed using various techniques, including familiar Arduino functions like digitalRead(), reading all inputs as binary values, or using defined names and bit operations for more granular control. The versatility of the SN74HC165N allows it to be adapted for a wide range of projects, from simple input expansion to complex input systems in embedded, industrial, and consumer electronics. Technically, the SN74HC165N features a 16-pin Dual In-line Package (DIP) configuration, with pins dedicated to functions such as data loading, clock input, and serial data output. It operates efficiently with standard TTL voltage levels and can be easily integrated into various circuit designs to enhance the input capabilities of a system. Practical applications include reading multiple input states in a single operation and handling these inputs efficiently within an Arduino sketch. The device is known for its reliability and quality, which is assured through stringent testing and quality control measures by Texas Instruments (TI). Despite its advantages, the SN74HC165N is sometimes compared with similar devices like the SN74HC595, which also offers parallel-to-serial data conversion but differs in operational specifics and use cases. The SN74HC165N remains a robust choice for expanding digital inputs in microcontroller projects, balancing functionality and ease of use.

Přehled

The SN74HC165N is an 8-bit parallel-load shift register, commonly used to add more digital inputs to an Arduino development board when the available pins are insufficient for the project requirements. This is particularly useful when interfacing with components that demand numerous pins, such as certain displays or a combination of multiple discrete sensors and actuators

. To expand digital inputs, an 8-position dip switch, with attached pull-down resistors, is connected to the shift register’s inputs (A – H), which constitute the 8 additional digital inputs. The pin naming conventions for the 74HC165 shift register may vary between different schematic representations and datasheets. For instance, the KiCad schematic symbol for the 74HC165 uses a different naming convention than the Texas Instruments (TI) datasheet. Throughout the tutorial, the TI naming convention is used for consistency. The shift register operates by reading all input values in a single read operation, which can then be processed in various ways within an Arduino sketch. Three primary approaches for reading these inputs are highlighted in the tutorial, each suited for different types of input requirements.

1. Using the Familiar digitalRead() Functionality: This method allows individual input changes to be detected using a familiar Arduino function.
2. Reading All Inputs Using Binary Values: This approach reads the entire byte of inputs at once, allowing for a more efficient handling of homogeneous input blocks.
3. Reading All Inputs Using Defined Names and Bit Operations: This technique offers a more granular control, useful for systems where inputs need to be addressed by specific names and manipulated through bitwise operations. Additionally, the tutorial provides an example that only prints input values if a change in one of the inputs is detected, which can be useful for reducing unnecessary data processing and output. This versatility in reading methods makes the SN74HC165N a robust solution for expanding digital inputs in various electronic projects, ensuring that users can adapt the approach to their specific needs.

Aplikace

The SN74HC165N 8-Bit Parallel-Load Shift Registers have a broad range of applications due to their ability to efficiently increase the number of digital inputs available to a microcontroller or an integrated system. These applications include projects that require interfacing with multiple sensors, switches, or other digital inputs that exceed the number of available input pins on a microcontroller. One of the common applications of the SN74HC165N is in microcontroller projects that require additional digital inputs without compromising the microcontroller’s limited I/O pins. By using the shift register, a microcontroller can read multiple digital inputs with just a few pins dedicated to the shift register’s control and data lines. This is particularly useful in projects involving Arduino boards, where users often face limitations in the number of available digital I/O pins. For example, the 74HC165 shift register can be connected to various input devices like DIP switches, push buttons, or even sensors to expand the microcontroller’s capability to read multiple inputs simultaneously

. The SN74HC165N can also be utilized in creating more complex input systems. For instance, in the context of reading inputs, it allows for binary representation of the states of multiple switches, enabling the user to read and manipulate multiple input states as a single binary value. This approach simplifies the software implementation by reducing the amount of code required to handle individual input states, which can be particularly beneficial in applications where all inputs are of the same type and can be processed collectively. Moreover, the SN74HC165N is applicable in situations where the design requires the integration of a large number of digital inputs into a compact form factor. This includes applications in embedded systems, industrial automation, and consumer electronics, where the shift register can be used to interface with control panels, keypads, and other input mechanisms while maintaining a minimal footprint.

Technické specifikace

The SN74HC165N is an 8-bit parallel-load shift register that provides parallel to serial data conversion. It operates by loading data from parallel inputs and then shifting it out serially. This device is highly versatile and commonly used in various electronic projects and applications due to its simplicity and reliability.

Konfigurace pinů

The SN74HC165N has a 16-pin Dual In-line Package (DIP) configuration.

• Pin 1 (SH/LD): Shift/Load, used to load the data from parallel inputs into the register.
• Pin 7 (QH): Serial Output.
• Pin 9 (QH’): Complementary Serial Output, useful for cascading multiple registers.
• Pin 15 (CLK): Clock, which shifts the data on the rising edge.
• Pin 10 (CLK_INH): Clock Inhibit, when tied LOW, allows the clock to operate normally. When HIGH, it disables the clock input, effectively stopping the shift register from clocking in new data .

Elektrické charakteristiky

• VCC (napájení): The chip operates at a typical voltage of 5V, connected to pin 16 (VCC) with pin 8 (GND) connected to ground.
• Rozsah vstupního napětí: The SN74HC165N accepts standard TTL input voltage levels.
• Output Pins: Pins 7 and 9 are the main data output pins, providing serial data that can be used to interface with other devices or microcontrollers .

Operational Use

In typical usage scenarios, the SN74HC165N allows for efficient data reading and writing with minimal pin usage on a microcontroller. By manipulating the SH/LD, CLK, and QH pins, users can load parallel data and read it serially, thus reducing the number of required I/O pins.

Example Circuit

A typical circuit using the SN74HC165N might include:

• Connecting pin 1 (SH/LD) to a microcontroller to control the loading of parallel data.
• Tying pin 10 (CLK_INH) LOW to enable the clock.
• Connecting pins 2-7 and 15 (parallel data inputs) to switches or other input devices.
• Using pin 7 (QH) as the serial data output to read the state of the inputs . The process involves initializing the shift register by writing a pulse to the load pin, setting up the register to send data, and then using functions such as shiftIn to read the data serially from the microcontroller .

Praktické aplikace

The SN74HC165N is frequently used in applications requiring multiple input monitoring with limited microcontroller I/O pins, such as reading a matrix of switches or expanding the input capabilities of a system. The flexibility of the clock inhibit feature allows for precise control over the timing of data acquisition

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Funkční popis

The SN74HC165N is an 8-bit parallel-load shift register that allows for parallel data input and serial data output. This component is widely used to expand the number of digital inputs available in microcontroller-based projects, such as those involving Arduino development boards. The shift register operates by first loading the parallel input data into a buffer, which is then shifted out serially

. When a key is pressed on a connected keyboard, the pressure causes a conductive layer on the underside of the key to contact and short-circuit conductive strips beneath it. This action produces a unique binary signal that is encoded and transmitted. In an alternative embodiment, signal encoding is accomplished through the calculator memory logic, and the specific mechanism used is incorporated by reference into various patents, including U.S. Patent No. 3,696,411. To read all inputs using the defined names and bit operations, the isrReadRegister() function is employed to read and capture the input values. This function is part of a tutorial that demonstrates how to add more digital inputs and outputs to an Arduino board using integrated circuits like the 74HC165. The shift register is configured such that when the load pin is pulsed, the parallel data is transferred into the register and can then be read serially. The SN74HC165N shift register operates in latching mode when not in the process of shifting. This means that it captures inputs until a shifting operation is initiated. The isrDigitalRead() function mimics the familiar digitalRead() function of the Arduino, but instead reads the inputs from the shift register. This mechanism is useful in scenarios where the project requires many switches or sensors, such as using DIP switches or jumpers. The data held on the output is inverted due to the complementary output from the 74HC165, meaning that a pressed pushbutton reads as LOW even though the actual state is HIGH. This inversion can be corrected in software to match the expected logic levels. The combined use of the 74HC595 and 74HC165 ICs in projects allows for both input and output expansion, making these shift registers versatile tools in digital electronics.

Quality Control and Reliability

Texas Instruments (TI) ensures the reliability of the SN74HC165N through stringent quality control and component qualification processes in accordance with JEDEC and industry standards. These processes include a variety of stress tests such as Highly Accelerated Stress Test (HAST), temperature cycling, autoclave testing, and evaluations of electromigration, bond intermetallic life, and mold compound life to ensure reliable operation over extended temperature ranges

. TI performs these qualification tests to guarantee that the SN74HC165N can withstand demanding operational conditions. However, it’s important to note that such testing should not be viewed as justifying the use of this component beyond its specified performance and environmental limits. Moreover, all parameters of products compliant with MIL-PRF-38535 are tested unless otherwise noted. For other products, production processing may not necessarily include testing of all parameters. TI reserves the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time, and may discontinue any product or service without notice. This adherence to rigorous testing and quality assurance protocols reflects TI’s commitment to providing reliable components for a wide range of applications, ensuring that the SN74HC165N operates effectively under various conditions.

Balení a dostupnost

Packaging of the SN74HC165N 8-Bit Parallel-Load Shift Registers involves several critical steps to ensure the functionality and reliability of the integrated circuits (ICs). The IC bonding process can include wire bonding, thermosonic bonding, flip chip, or tape automated bonding (TAB). Following this, IC encapsulation or integrated heat spreader (IHS) installation is performed to protect the die and enhance thermal management. Molding with a special plastic compound, which may contain glass powder as filler to control thermal expansion, is another crucial step. Subsequent steps include baking, electroplating (which plates the copper leads with tin to facilitate soldering), laser marking or silkscreen printing, and trim and form (which separates and shapes the lead frames for mounting on a printed circuit board)

. The final stages involve IC testing to verify the functionality and the integrity of the die-to-pin connections. These steps are part of the broader back end, post-fab, ATMP (Assembly, Test, Marking, and Packaging) processes and may be conducted by OSAT (OutSourced Assembly and Test) companies, which operate independently from semiconductor foundries. These foundries are responsible for the front end processes, such as photolithography and etching . The packaging methods include the use of plastic or ceramic materials. The die is mounted, and the bond pads are connected to the package pins using tiny bondwires. Initially, this process was done manually, but it is now performed by specialized machines. Traditional bondwires were made of gold, but due to RoHS mandates, lead-free options are now used. Flip-chip packaging can distribute bond pads across the die’s surface rather than just on the edges. Chip Scale Packages (CSP) are also an option, being almost the same size as the die itself, as opposed to the much larger traditional dual in-line packages . In terms of availability, the packaged chips undergo final testing to ensure they were not damaged during packaging and that the connections are intact. This meticulous process ensures that only the highest quality components reach the market, maintaining the reliability and performance standards expected in the semiconductor industry .

Usage in Circuits

The SN74HC165N 8-Bit Parallel-Load Shift Registers are integral components in many digital circuit designs, particularly when additional input pins are needed for a microcontroller like the Arduino. The shift register can read multiple input signals and communicate them serially to the microcontroller, thereby saving valuable GPIO pins on the controller.

Integration with Microcontrollers

To use the SN74HC165N shift register with a microcontroller, you must follow several steps to ensure proper connections and functionality. The shift register can provide 8 additional digital inputs with a single 8-bit data transfer, and these can be expanded further by daisy-chaining multiple ‘165 chips together

. This feature allows the system to handle numerous input signals without requiring additional connections to the Arduino, thus making it a versatile choice for complex designs.

Connecting the Shift Register

The typical steps for connecting a SN74HC165N shift register to an Arduino microcontroller involve:

1. Starting with the Arduino UNO: Gather the necessary components including one Arduino UNO, one SN74HC165N shift register, 8 slide switches, and connecting wires.
2. Ground Connections: Identify the GND pins on both the shift register and the Arduino. Connect the GND pin of the shift register (pin 8) to one of the available GND pins on the Arduino.
3. Load Pin Connection: Connect the Shift/Load (SH/LD#) pin of the shift register (often referred to as the latch pin) to a designated digital pin on the Arduino, such as pin 4.
4. Clock Line Connection: The Serial Clock (CLK) pin of the shift register should be connected to another digital pin on the Arduino, such as pin 3.
5. Serial Data Output Line: Connect the QH pin (data output) of the shift register to the designated serial input pin on the Arduino, such as pin 2.

Reading Inputs

To read the input signals from the connected switches, an Arduino sketch can be used to manage data transfer. The digital signals from the switches are processed through the shift register and transferred to the Arduino for further action. By using bitwise operations, the system can detect changes in the input signals and process them accordingly

. For example, in a project where four daisy-chained SN74HC165N chips are used, you can gain 32 additional input pins (4 x 8) with a 32-bit data transfer. The data from these inputs can be read into the Arduino in a single operation and subsequently processed to detect and handle input changes efficiently.

Example Code

An example Arduino sketch might include code snippets to read and print input values only when a change is detected. This approach uses bit operations to sequence through all input bits and provides an 8-bit binary representation for all inputs in the Serial Monitor

.

void readAndPrintInputsOnChange() {
// Function code to read inputs and print only when changes are detected
...
}

By constantly calling a function like readAndPrintInputsOnChange(), the Arduino can monitor and react to changes in the input states dynamically

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Výhody

The SN74HC165N 8-Bit Parallel-Load Shift Register offers several advantages in electronic design and applications. Firstly, the device supports high-speed parallel-to-serial data conversion, which is essential for reducing data transfer times in digital systems. Additionally, the SN74HC165N’s efficient design minimizes power consumption, making it suitable for battery-operated devices where energy efficiency is crucial. Moreover, the flexibility of the SN74HC165N allows it to be easily integrated into various circuit designs. The ability to load data in parallel and shift it serially provides a versatile solution for handling multiple data streams simultaneously, which is particularly beneficial in complex digital systems. Furthermore, the robust design of the SN74HC165N ensures reliable operation across a wide range of temperatures and voltages, enhancing the durability and longevity of the end products in which it is used. The advantages of the SN74HC165N are further underscored by the principles of patent law, which emphasize the importance of granting inventors a fair scope of protection for their inventions. This is reflected in the doctrine of equivalents, which recognizes that different embodiments of an invention can still be considered equivalent if they perform substantially the same function in substantially the same way to achieve the same result

. This principle helps preserve the incentive for innovation by ensuring that inventors are not unduly restricted to the specific embodiments disclosed in their patents. Lastly, the design and operation of fabrication processes can significantly impact the yield of devices like the SN74HC165N. By optimizing these processes, manufacturers can improve the overall efficiency and quality of the shift registers produced. This not only benefits the manufacturers by reducing production costs but also ensures that end-users receive high-quality and reliable components for their electronic applications.

Omezení

TI argues that the Commission required too narrow a construction of the ‘921 patent claims, contrary to this body of precedent, thereby limiting the claims to the means illustrated in the specification. As stated in D.M.I., interpreting “means plus function” limitations as restricted to a specific means set forth in the specification would nullify the provision of Section 112, which mandates that the limitation should be construed to cover the structure described in the specification and its equivalents

. This principle is underscored by the court’s holding that there is no requirement for applicants to describe or predict every possible means of achieving the function specified. Additionally, the court enforces offers to compromise only if accepted; in this case, it was not. The court determined that a nationwide response was inappropriate due to the lack of knowledge about laws in other jurisdictions and the absence of briefing on the matter. Consequently, production was limited to California, specific documents related to complaints, answers, and merits rulings by courts or other tribunals. Confidential information in these documents can be redacted with an appropriate log. Regarding Request for Production (RFP) 23, the court denied the demand for claims made to the carrier that did not result in a filed lawsuit or arbitration. However, the court granted the motion concerning the two interrogatories about those involved in the decision-making process, allowing defendants to provide this information through documents or a list. Verified responses without objection, except for privilege or third-party privacy, are to be served within 30 days. Lastly, the court awarded $11,390 in sanctions against the defendant, payable within 30 days, due to the reduced scope of the RFP and the review of supporting documents and declarations. The court also provided general guidelines on discovery responses, emphasizing that general objections are not permitted without reasonable limitation by the responding party. Objections deemed unduly burdensome require an evidentiary basis, including what the burden of compliance would entail.

Srovnání s podobnými zařízeními

The SN74HC165-EP is an enhanced version of the SN74HC165N, designed to provide improved functionality and reliability in various applications. One notable aspect is its controlled baseline, ensuring consistency in performance by using one assembly/test site and one fabrication site

. Additionally, it offers extended temperature performance from –55°C to 125°C, making it suitable for more demanding environments. Enhanced Diminishing Manufacturing Sources (DMS) support and enhanced product-change notifications further contribute to its reliability and longevity in critical applications. In terms of functionality, the SN74HC165-EP features a 2-V to 6-V VCC operation range and outputs capable of driving up to 10 LSTTL loads, which highlights its robust operational capabilities. It also has low power consumption with a maximum ICC of 80 µA and a typical propagation delay (tpd) of 13 ns. The device includes ±4-mA output drive at 5 V and low input current of 1 µA max, ensuring efficient performance with minimal power draw. Similar to the SN74HC595, the SN74HC165-EP supports parallel-to-serial data conversion, making it versatile for various applications. Both devices include complementary outputs and gated clock inputs, enhancing their functionality in digital systems. However, the SN74HC165-EP distinguishes itself with its direct overriding load (data) inputs, which provide an additional layer of control during operation.

Další zdroje

For those interested in further exploring the SN74HC165N 8-Bit Parallel-Load Shift Registers, there are several resources available that can provide valuable information and support for your projects.

Component Datasheets

To understand the specifications and operational parameters of the SN74HC165N, the datasheet is an essential resource. You can find the datasheet for the 74HC165 on various electronics component websites, including Texas Instruments’ official website

. Additionally, for those working with complementary components, the 74HC595 shift register specs can also be beneficial.

Tutorials and Guides

Arduino enthusiasts can benefit from detailed tutorials that explore the use of the SN74HC165N in various projects. One such tutorial explains how to add more digital inputs to your Arduino board using this shift register. This guide is part of a three-part series that also covers other IC chips like the 74HC595 and the MCP23017

. The tutorials include step-by-step instructions, code examples, and circuit diagrams to help you get started.

Code Repositories

For practical implementation, accessing the source code and examples is crucial. The final source code and schematics used in related tutorials are often shared on platforms like GitHub, where you can find fully commented versions of the code. These comments provide additional insights such as program descriptions, circuit connections, and code clarifications. Moreover, the comments are Doxygen compatible, allowing for the generation of comprehensive code documentation

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Printable Resources

For those who prefer offline resources, many tutorials and guides are available in printable PDF formats. This can be particularly useful for referencing while working on physical projects or for those who prefer reading printed documents over digital screens

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Community and Support

Engaging with the community can provide additional support and inspiration. Websites dedicated to open-source hardware projects, such as forums and blogs, allow you to share your experiences and seek advice from fellow enthusiasts. For instance, you can leave comments and questions on tutorial pages to interact with the author and other readers, which can lead to a more enriching learning experience

. These resources collectively offer a comprehensive toolkit for anyone looking to leverage the SN74HC165N in their electronic projects, ensuring both novice and experienced users can achieve their project goals effectively.