The test repository for the iSensor FX3 API and FX3 Firmware is hosted here. This repository includes source for all test cases (written in C# running on nUnit 2.6.4) and a simple nightly build CI script for a Windows host. All test cases are system level tests running on target hardware.

The FX3 API manages all the complex USB transactions and implements all the necessary tools to begin capturing high-speed, high-performance data in custom applications. This .NET-compatible API, written in VB.NET and C#, includes data streaming features tailored to reliably capturing inertial sensor data at the maximum data rate.

The FX3 Firmware was designed with compatibility and flexibility in mind. The firmware attempts to follow the Cypress program workflow and relies on FX3 system threading, execution priority, and event flags to execute firmware subroutines and transmit sensor data. Custom vendor commands trigger subroutines embedded in the firmware that read and write SPI data, measure external pulses, generate clock signals, and manage board configuration. Several SPI streaming modes are implemented, which allow applications to communicate with nearly every device in the iSensor portfolio. The freely-available, Eclipse-based, Cypress EZ USB Suite was used for all firmware development.

Static-generated documentation for the FX3 API .NET library and firmware can be found here: https://juchong.github.io/iSensor-FX3-API/

This firmware was designed around the Cypress EZ-USB FX3 SuperSpeed USB Controller (CYUSB3014 and CYUSB2014) family of USB interface ICs offered by Cypress.

The EVAL-ADIS-FX3 includes many additional firmware and hardware features that make testing, characterizing, and developing software for iSensor products easy. Firmware and API support for this board are included in release v2.5 onward.

The EVAL-ADIS-FX3 features include:

• A dedicated, onboard 3.3V, 2A linear regulator designed for high-transient applications
• A USB-C connector (USB 2.0 compatible only)
• An onboard, field-upgradable EEPROM with USB bootloader fallback
• A software-selectable OFF / 3.3V / 5V IMU supply output with overcurrent and short protection
• A JST-XH-2 external supply connector
• Selectable USB and external supply selection
• Onboard status LEDs for each IMU GPIO pin
• An iSensor standard, 16-pin, 2mm connector for compatibility with existing iSensor breakout boards and adapters
• An additional 10-pin, 2mm connector for feature expansion. As of writing, the firmware and API include support for:
• FX3 UART debugging
• Four additional GPIO pins for external test equipment triggering and sensing (separate from the IMU GPIOs)
• Separate 3.3V and 5V supplies from the DUT supply meant to power external level shifters, drivers, interface ICs, etc.
• An extra, “bit-banged” SPI port to allow for “non-standard” SPI configurations and communication with external hardware (ADCs, DACs, protocol interface ICs, etc.)
• An I2C port meant for interfacing with I2C-compatible inertial sensors
• Concurrent, multi-board data capture capability. Multiple EVAL-ADIS-FX3 boards can be connected to the same PC and can concurrently capture data independently of each other
• Very low CPU usage while capturing data, even on older Windows machines
• Windows 7, 8, and 10 compatibility
• 1.5“ x 1.75” PCB footprint

Design files for the breakout board is available in the hardware folder of the API repository.

A breakout board designed for interfacing iSensor devices with the Cypress SuperSpeed Explorer Kit (CYUSB3KIT-003) was introduced as a temporary solution while a more feature-rich offering was developed. Both boards will continue to be supported in future firmware revisions.

Design files for both breakout boards are available in the hardware folder of the API repository.

The Explorer Kit requires three jumpers to be installed to operate correctly as shown in the image below. Jumpers J2, J3, and J5 must be installed when using the SuperSpeed Explorer Kit. Jumper J4 must be open to allow booting from the onboard EEPROM.

The API is designed such that custom bootloader firmware is loaded into FX3 RAM prior to executing the Connect()function. This custom bootloader exposes LED blinking commands, a unique FX3 serial number in the USB vendor descriptor, and more importantly allows the main application firmware to be loaded over the bootloader firmware without a reboot. These features allow multiple FX3 boards to communicate with multiple application instances on a single machine. They also provide a means of visually identifying multiple FX3 boards when preparing to initiate a connection. All connected boards should be running the bootloader firmware to be considered as a "valid" board by the API. If an FX3 board is identified by the Cypress driver, but is not running the custom bootloader, then it will be ignored by the API. FX3 boards must be running the custom bootloader firmware prior to loading application firmware~

The API provides functions to detect, identify, and program FX3 boards in user applications. Once a valid board has been identified, the Connect() function will push the application firmware into FX3 RAM, overwriting the bootloader firmware. The function also verifies whether communication with the FX3 board is as expected.

The FX3 API translates high-level user commands into the necessary low-level Cypress API calls required to communicate with the FX3 firmware. The API also simplifies SPI configuration, data ready behavior, and device management. Using the vendor command structure outlined by Cypress, different SPI capture and streaming modes can be called based upon the user's requirements. Additional functionality such as generating clocks and pulses, measuring the time between pin pulses, waiting for external triggers, and a few other features have also been baked into the firmware and API.

An example application was developed to provide users with a simple starting point. The application repository can be found here.

As of v1.0.6, custom, signed, Analog Devices drivers must be used to communicate with the iSensor FX3 Firmware. The driver installation package can be found in the drivers folder in this repository or downloaded directly from here.

2. iSensor FX3 Eval

The FX3 API implements in-house closed-source interface libraries (IRegInterface and IPinFcns) included in the resources folder in this repository. These libraries are required to maintain control and consistency with other iSensor devices and are defined in the AdisApi.

This API (and the FX3-specific classes) should be used in place of the AdisBase and iSensorSpi classes for performing read/write operations. Unlike iSensorSpi, this class includes all the connection and SPI setup functions defined internally. This allows the FX3 API to perform the device connection and enumeration operations without having to pass the class an instance of AdisBase.