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ECE 477 DESIGN REVIEW TEAM 2 FALL 2011 Members: Bo Yuan, Yimin Xiao, Yang Yang, Jintao Zhang
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Outline Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation PCB layout Software design/development status Project completion timeline Questions / discussion
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Project Overview The project we propose is a digital oscilloscope with playback function that provides almost any function of a typical oscilloscope, such as digital sampling, signal processing, scaling, cursor setting, reconstruction and visualization of signals. Additional features such as recording and replicating signals as a function generator, and write data to external storage (SD card).
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Project-Specific Success Criteria An ability to sample analog voltage signal range from -12 V to 12 V via BNC; An ability to reconstruct and display the sampled signal on VGA display; An ability to create user interface and realize basic signal measurements, such as frequency and peak- to-peak voltage; An ability to store/load the sampled signal to/from external memory; An ability to replay a stored signal.
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Block Diagram
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Block Diagram, System Level
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Component Selection Rationale Power Supply: Using a standard 20 pin-Computer power supply unit. (Easy to use) Use linear transistor 7805/7905/78M33 to provide low noise signal. Although 5V and 3.3V are available from the power supply, but along with a ripple voltage at 300mV. No significant current will be drawn from +/-5V line, large ripple voltage will be used in driving the analog MUX (+/-12V) and FPGA module (+5V), which has its own on board linear power supply system. Using a 3V voltage reference for A/D conversion reference.
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Component Selection Rationale Analog circuit: MAX14752: Analog MUX Advantage: Large tolerance (VSS-2 to VDD+2) compare to ADG1414 (VSS- 0.3 to VDD+0.3). Easy to control: Serial bus control, no SPI line require. Got free sample from MAXIM, ADG1414 cost 8 dollar a piece. Disadvantage: High On-Resistance: 60 Ohm and ADG1414 is only 9.5 Ohm (Typ.). More Pins to MCU: Each require four lines to controller, but ADG1414 is SPI shift register which can be implemented serially.
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Component Selection Rationale INA118: Instrumentation Amplifier Advantage: low distortion, high tolerance (+/-40V), voltage shift up by V ref (1.5V). LF411: Output driver op-amp: Advantage: Low offset, low distortion, high power (capable to drive coaxial wires)
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Component Selection Rationale Digital Circuit: MCU – STM32F407VG Sampling rate 2.4 MHz maximum. Relatively large RAM size (192 KB). Crystal Clock: 26MHz Crystal: Allowed maximum external clock. ARM Cortex- M4 will use an internal PLL to generate higher frequency clock up to 168MHz. Secondary clock (32.768KHz) is also laid out on board in case for need of precise clocking. FPGA – Spartan 3E VGA support. Older version of the Spartan series, avoid voltage conversion.
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Packaging Design
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Schematic/Theory of Operation Analog Input/ Output
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Schematic/Theory of Operation Microprocessor
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Schematic/Theory of Operation Display Unit
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Schematic/Theory of Operation User Interface
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PCB Layout: General Layout
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PCB Layout: Through Hole/Via
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PCB Layout: Top Copper
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PCB Layout: Bottom Copper
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Software Design/Development Status
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Software Design Development Status BlockProgress Timer ConfigDone I 2 C Master ConfigDone I 2 C Slave ConfigIn progress ADC ConfigDone with one channel GPIOsIn progress SubroutinesNot started DACNot started USBDone with config VGA displayNot started
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Project Completion Timeline
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QUESTIONS / DISCUSSION
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