Tags: biomimetics/imageproc_pcb
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ImageProc 2.5 Rev. A Final silk screen and manufacturing modifications. Submitted for prototype manufacturing on 7/26/2012. ImageProc 2.5 updates the ImageProc with several new features and updated silicon, while focusing on on enhanced manufacturability and ease of modification. Software revisions to the octoroach and imageproc-lib codebases are forthcoming. Process/Manufacturing * Changed from 2- to 4-layer process for routing and modificiation flexibility * Functional units consolidated and rearranged for better isolation * All ICs now on top side, (almost) all passives on bottom * 6 mil trace/space for cheaper manufacturing processes in the prototyping stage * Plane pours on all layers. Stack-up is Ground/Ground/Power/Ground. Signals run in all layers. * All-new normalized part footprints, schematic symbols, and silk screen. * Schematic now uses 5 sheets for enhanced readability. A non-free EagleCAD license is now required to view the files. * A 10 mil tKeepout/bKeepout margin is now enforced at the boundaries of the board to ensure that the pick-and-place machine can reach all pads when the board is clamped into the board cradle. * Many nets have been added and others renamed for clarification * Much more conservative standards for component spacing Power * Panasonic MN13822-L voltage supervisor replaced with Torex XC61GC3002HR-G because the MN13822 has been discontinued * Micrel MIC5320-JGYML 1.8/2.5 V regulator replaced with MIC5335-JGYMT because the MIC5320 is no longer available from suppliers. Microcontroller * Many pins have been relocated to make room for new features. * Added bypass capacitors for each VDD/VSS pair and a filtering inductor to the VDD/AVDD connection, according to Microchip's recommendations Radio * ZigBee radio updated from Atmel AT86RF233 to the Atmel AT86RF233, which presents an identical electronic and software interface, but with silicon for an additional +1 dBm of transmit power * Replaced ECS ECS-2033-160 16 MHz crystal with NDK NX2520SA to meet the coupling capacitance and frequency tolerance standards required by Atmel * Completely revised passive values, tolerances, and dielectrics to conform with Atmel requirements * The antenna relocated to lower-right corner of the board, away from noisy motor control electronics. * Ground planes added and RF routing revised to conform with Atmel requirements and best practices. * Added TX/RX LEDs, to aid debugging radio issues Motor Control * Motor driver MOSFETs and Allegro H-bridge removed and replaced with four full 1A/channel H-bridges based on the TI DRV8833 dual H-bridge IC. This consumes all PWM pins on the dsPIC33 * Back-EMF sensing on all four H-bridge channels is made possible by four dual- to single-ended conversion amplifiers based on the Linear Technology LTC6088 quad op-amp. Back-EMF signals are connected to AN8/9/10/11. Connectors and Peripherals * InvenSense ITG-3200 accelerometer replaced with the InvenSense MPU-6000 Gyroscope+Accelerometer, freeing up I2C2. The MPU-6000 is an SPI part, and has been placed on SPI2 with the Atmel DataFlash. The SPI interface will allow for high-speed synchronous sampling of the IMU. The FSYNC input of the MPU-6000 has been connected to the HREF line of the camera interface, so the user may optionally synchronize IMU sampling with the camera lines. * Analog Devices ADXL345 accelerometer removed, as it was made redundant by the MPU-6000. * Atmel AT45DB321D 32 Mbit DataFlash replaced with Atmel AT45DB642D 64 Mbit part. * Solder pads are now 50x100 mil, for easier soldering and more reliable connections * Vias added to motor/power connections, for wire strain relief * Added additional two 6-pin Molex FPC connectors. Once exposes battery voltage and UART2 TX/RX, and is intended for the OMAP Backpack and FeelerProc peripherals. The other exposes I2C1 SCL/SDA and 3.3V, and is intended for daisy-chained connection to austriamicrosystems high-precision GMR magnetic absolute encoders