Hardware Integration: uINS-3 Module¶
Our module must be hand soldered ONLY! Solder reflow may result in damage! See Soldering for details.
|1||USB_P||I/O||USB Data Positive Line|
|2||USB_N||I/O||USB Data Negative Line|
|3||GPS_VBAT||-||GPS backup supply voltage. (1.4V to 3.6V) enables GPS hardware backup mode for hot or warm startup (faster GPS lock acquisition). MUST connect GPS_VBAT to VCC if no backup battery is used.|
|4||G1/Rx2*/RxCAN*||I/O||GPIO1. Serial 2 input (TTL). Serial input pin from CAN transceiver**.|
|5||G2/Tx2*/TxCAN*/STROBE||I/O||GPIO2. Serial 2 output (TTL). Serial output pin to CAN transceiver**. Strobe time sync input.|
|6||G6/Rx1/MOSI||I/O||GPIO6. Serial 1 input (TTL). SPI MOSI|
|7||G7/Tx1/MISO||I/O||GPIO7. Serial 1 output (TTL). SPI MISO|
|8||G8/CS/STROBE||I/O||GPIO8. SPI CS. Strobe time sync input.|
|9||G5/SCLK/STROBE||I/O||GPIO5. SPI SCLK. Strobe time sync input.|
|I/O||GPIO9. Hold LOW during boot to enable SPI on G5-G8. Strobe time sync input or output.|
|12||nRESET||I||System reset on logic low. May be left unconnected if not used.|
|17||Reserved (CE)||-||Leave unconnected. CHIP ERASE used in manufacturing. !!! WARNING !!! Asserting a logic high (+3.3V) will erase all IMX flash memory, including calibration data.|
|18||G4/Rx0||I/O||GPIO4. Serial 0 input (TTL)|
|19||G3/Tx0||I/O||GPIO3. Serial 0 output (TTL)|
|20||GPS_PPS||O||GPS PPS time synchronization output pulse (1Hz, 10% duty cycle)|
|22||VCC||-||3.3V regulated supply|
*Available on IMX-3.2 and later.
**External transceiver required for CAN interface.
The following schematic demonstrates a typical setup for the μINS module. A rechargeable lithium backup battery enables the GPS to perform a warm or hot start. If no backup battery is connected, GPS.VBAT should be connected to VCC and the module will perform a cold start on power up. If the system processor is not capable of updating the μINS firmware, it is recommended to add a header to an alternate μINS serial port for firmware updates via an external computer. The reset line is not necessary for typical use.
The following are recommended components for the typical application. Equivalent or better components may be used.
|BAT1||Panasonic||ML-614S/FN||BATTERY LITHIMU 3V RECHARGABLE SMD|
|D1||Panasonic||DB2J31400L||DIODE SCHOTTKY 30V 0.03A SMINI2|
|R1||RES 1.00K OHM 1/16W 1%|
|C1||CAP CER .10UF 50V X7R 10%|
The SPI interface is enabled by holding the pin 10 low during boot up.
These parts must be hand soldered ONLY! Solder reflow may result in damage!
The IMX, uAHRS, and uIMU are designed as surface mount components that can be hand soldered onto another circuit board. These parts are not designed to withstand the high temperatures associated with standard solder reflow processes. Solder assembly must be done using a soldering iron.
Recommend PCB Footprint and Layout¶
A single ceramic 100nF decoupling capacitor should be placed in close proximity between the Vcc and GND pins. It is recommended that this capacitor be on the same side of the PCB as the μINS and that there not be any vias between the capacitor and the Vcc and GND pins. The default forward direction is indicated in the PCB footprint figure and on the μINS silkscreen as the X axis. The forward direction is reconfigurable in software as necessary.
Open source hardware design files, libraries, and example projects for the IMX module are found at the Inertial Sense Hardware Design repository hosted on GitHub. These include schematic and layout files for printed circuit board designs, and 3D step models of the InertialSense products usable for CAD and circuit board designs.
Reference Design Projects¶
The EVB-2 and IG-1 circuit board projects serve as reference designs that illustrate implementation of the IMX PCB module.