\u0417\u0435\u043c\u043b\u044f NI USB-8451<\/strong> is a USB I\u00b2C, SPI and digital I\/O interface designed for communicating with integrated circuits, sensors, memory devices and embedded-system peripherals. It allows a computer to generate serial commands and read device responses without developing a dedicated microcontroller interface.<\/p>\n The USB-8451 supports SPI clock rates up to 12 MHz and I\u00b2C clock rates up to 250 kHz. Eight chip-select outputs simplify communication with multiple SPI peripherals, while eight individually configurable digital I\/O lines support reset, interrupt, status and general control signals.<\/p>\n The I\u00b2C interface uses open-drain clock and data lines and supports standard clock selections from 32 kHz through 250 kHz. Software-configurable pull-up functionality and the programmable reference voltage help adapt the interface to different peripheral logic levels.<\/p>\n The USB-8451 is also compatible with many SMBus devices. Engineers should verify device addressing, voltage, pull-up resistance, clock-stretching behavior and protocol-specific timing before connecting a target circuit.<\/p>\n The SPI interface supplies SCLK, MOSI and MISO signals and supports clock selections up to 12 MHz. Eight chip-select outputs allow software to address several peripherals without adding a separate external decoder.<\/p>\n Before communication begins, configure the correct clock polarity, clock phase, bit order, chip-select behavior and clock rate specified by the peripheral manufacturer.<\/p>\n The eight DIO lines can be independently configured as inputs or outputs. They can monitor interrupt and status signals or control reset, enable, write-protect and mode-selection pins associated with the serial device.<\/p>\n Digital lines are intended for logic-level interfacing. External buffer or driver circuitry is required when controlling relays, lamps, motors or other higher-current loads.<\/p>\n Confirm whether the application requires the enclosed USB-8451 or the OEM version. Their mechanical connectors and intended installation methods are different.<\/p>\n The interface can configure registers and collect data from temperature sensors, accelerometers, ADCs, DACs and other serial peripherals. Its digital lines can simultaneously control reset or monitor a data-ready interrupt.<\/p>\n Automated software can write configuration data to compatible I\u00b2C or SPI memory, read it back and verify the result. Device voltage, addressing, page size and write-cycle timing must be configured correctly.<\/p>\n Install a compatible NI-845x driver before connecting the interface to the host computer.<\/p>\n Connect the USB cable, allow the computer to detect the device and confirm its presence in NI Measurement & Automation Explorer.<\/p>\n Determine the target logic voltage and configure the reference voltage and pull-up arrangement before wiring the device.<\/p>\n Connect the required I\u00b2C or SPI signals and establish a common ground. Keep high-speed SPI wiring short and avoid unterminated branches.<\/p>\n Start with a low clock rate and perform a known register-read or identification transaction before building the complete automated sequence.<\/p>\n Check the device address, common ground, pull-up resistors, reference voltage and whether the target uses a shifted or unshifted address representation.<\/p>\n Verify clock polarity, clock phase, bit order, chip-select assignment and maximum peripheral clock rate. Reduce the clock rate while diagnosing signal-integrity problems.<\/p>\n Use an external logic buffer or power driver. USB-8451 digital lines are intended for communication and logic control rather than powering external loads.<\/p>\n Shorten wiring, verify the ground connection and examine the signals with an oscilloscope or logic analyzer. Incorrect pull-up resistance can cause slow I\u00b2C edges.<\/p>\n Check the USB cable, port and NI-845x installation. Avoid unpowered hubs and test the interface on another known-good USB port.<\/p>\n It supports I\u00b2C, compatible SMBus communication, SPI and static digital I\/O.<\/p>\n The specified maximum SPI clock rate is 12 MHz.<\/p>\n The I\u00b2C interface supports selected clock rates up to 250 kHz.<\/p>\n The device provides eight dedicated chip-select outputs.<\/p>\n No. It generates and receives protocol transactions, while a logic analyzer primarily captures and analyzes existing digital activity.<\/p>\nKey Features of the USB-8451<\/h3>\n
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USB-8451 Technical Specifications<\/h2>\n
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\n Product Model<\/th>\n USB-8451<\/td>\n<\/tr>\n \n Product Type<\/th>\n USB I\u00b2C, SPI and digital I\/O interface<\/td>\n<\/tr>\n \n SPI Role<\/th>\n Controller\/master interface<\/td>\n<\/tr>\n \n Maximum SPI Clock<\/th>\n 12 MHz<\/td>\n<\/tr>\n \n SPI Transfer Size<\/th>\n 8 bits<\/td>\n<\/tr>\n \n SPI Chip Selects<\/th>\n 8<\/td>\n<\/tr>\n \n Maximum I\u00b2C Clock<\/th>\n 250 kHz<\/td>\n<\/tr>\n \n I\u00b2C Modes<\/th>\n Standard mode and supported rates through 250 kHz<\/td>\n<\/tr>\n \n Fast Mode Plus<\/th>\n Not supported<\/td>\n<\/tr>\n \n High-Speed I\u00b2C Mode<\/th>\n Not supported<\/td>\n<\/tr>\n \n Digital I\/O Lines<\/th>\n 8<\/td>\n<\/tr>\n \n DIO Direction<\/th>\n Individually software selectable<\/td>\n<\/tr>\n \n DIO Output Type<\/th>\n Push-pull or open-drain<\/td>\n<\/tr>\n \n USB Interface<\/th>\n USB Full-Speed, 12 Mb\/s<\/td>\n<\/tr>\n \n Auxiliary Supply<\/th>\n 5 V output<\/td>\n<\/tr>\n \n I\/O Connectors<\/th>\n 2 \u00d7 16-position screw-terminal headers<\/td>\n<\/tr>\n \n USB Connector<\/th>\n USB Type-B receptacle<\/td>\n<\/tr>\n \n Weight<\/th>\n 84 g<\/td>\n<\/tr>\n \n Operating Temperature<\/th>\n 0\u00b0C to 45\u00b0C<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n I2C Communication<\/h3>\n
SPI Communication<\/h3>\n
Eight Digital I\/O Lines<\/h3>\n
USB-8451 Part Number and Accessories<\/h2>\n
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\n Item<\/th>\n \u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435<\/th>\n<\/tr>\n \n USB-8451<\/td>\n Enclosed USB I\u00b2C\/SPI interface with screw-terminal connections<\/td>\n<\/tr>\n \n USB-8451 OEM<\/td>\n Board-level version intended for integration into custom systems<\/td>\n<\/tr>\n \n 16-Position Terminal Plugs<\/td>\n Provide field wiring access to serial and digital signals<\/td>\n<\/tr>\n \n USB Type-A to Type-B Cable<\/td>\n Provides host communication and operating power<\/td>\n<\/tr>\n \n Logic-Level Adapter<\/td>\n Used when the target voltage or electrical interface requires translation<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n USB-8451 Applications<\/h2>\n
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Sensor and IC Evaluation<\/h3>\n
EEPROM and Memory Programming<\/h3>\n
USB-8451 Installation Workflow<\/h2>\n
Step 1: Install the NI-845x Driver<\/h4>\n
Step 2: Connect and Identify the Hardware<\/h4>\n
Step 3: Configure the Electrical Interface<\/h4>\n
Step 4: Connect the Peripheral<\/h4>\n
Step 5: Test a Basic Transaction<\/h4>\n
USB-8451 Troubleshooting<\/h2>\n
The peripheral does not acknowledge an I2C command<\/h4>\n
SPI data is incorrect<\/h4>\n
The DIO line cannot drive the connected load<\/h4>\n
Communication is intermittent<\/h4>\n
The USB-8451 is not detected<\/h4>\n
USB-8451 Comparison<\/h2>\n
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\n \u041c\u043e\u0434\u0435\u043b\u044c<\/th>\n Interface<\/th>\n Best Suited For<\/th>\n<\/tr>\n \n USB-8451<\/td>\n 250 kHz I\u00b2C, 12 MHz SPI, 8 DIO<\/td>\n General embedded-device communication<\/td>\n<\/tr>\n \n USB-8451 OEM<\/td>\n Same interface in board-level format<\/td>\n Integration into custom fixtures and products<\/td>\n<\/tr>\n \n USB-8452<\/td>\n Higher-performance I\u00b2C\/SPI interface<\/td>\n Applications requiring faster communication or advanced streaming<\/td>\n<\/tr>\n \n USB-6000<\/a><\/td>\n Analog input, DIO and counter<\/td>\n Voltage measurement rather than serial-bus communication<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n USB-8451 Frequently Asked Questions<\/h2>\n
What protocols does the USB-8451 support?<\/h4>\n
What is the maximum SPI clock rate?<\/h4>\n
What is the maximum I2C clock rate?<\/h4>\n
How many SPI peripherals can be selected directly?<\/h4>\n
Does the USB-8451 replace a logic analyzer?<\/h4>\n
Request a Quote for the USB-8451<\/h3>\n