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Projects

'Deej' Audio Controller

Communicates with host PC over serial to change volume on a per-application basis. Current volume, as saved in EEPROM, is displayed on a 10-segment LED bargraph per channel. 

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  • AVR ATTiny-2 Microcontroller​​

    • UART

    • EEPROM

    • Interrupts

  • Shift Registers for LED control​

  • Incremental Encoders

    • Push-button mute​

    • RC Debounce Circuit

  • Custom PCB with backside as faceplate​

    • 3D-printed enclosure​

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Low-Profile BLE Keypad

Bluetooth Low-Energy keypad uses diode-protected scanning matrix to detect keypresses and send HID packets to host device. Powered by small lithium ion battery with polyfuse and protection circuit.

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  • NRF52 Microcontroller

    • Task-Event Interrupts

    • Code runs beside Nordic Semiconductor 'SoftDevice' BLE Stack

    • I2C

  • Scanning matrix for expandability w/ less GPIO​

  • Long runtime on single charge

    • Slave Latency​

    • Scanning matrix doesn't run until keypress detected

  • Status LED indicates BLE pairing status

  • I2C EEPROM included for future features, such as switchable key 'layers'

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Wireless 'Cloud' LED Ring

Animated individually-addressable LEDs driven by microcontroller. Capable of being turned on by (local) capacitive touch, or wirelessly by another unit on the same channel. Each unit turns on the radio to listen only periodically to conserve battery.

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  • AVR AT-Tiny Microcontroller

    • Interrupts​

    • Timers

    • SPI

  • NRF24L01+ RFIC​

    • Polled RX for low-power​

    • Packet-based 2.4GHz protocol

  • Boost converter for LEDs​

  • LED patterns configurable with DIP switches​

  • Battery charge status animated on LEDs

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IN-18 Nixie Tube Clock

Displays current time with high-voltage, low current IN- series Nixie tubes. 12V DC input is stepped up to >150V DC to light Nixie tubes. Time is maintained through power-outage with backup coin cell.

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  • AVR ATMega Microcontroller

    • I2C​

    • Interrupts

  • I2C RTC with Battery Backup​

  • Multiple Power Domains - 5V, 12V, HV

  • Capacitive 'Guard Ring' shuts off HV when a finger is near, also acts as a toggle switch

  • Automatically adjusts for DST (legacy)

  • Custom PCB and acrylic top plate

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'µMeasure' Current Meter

Automatic shunt-switcher for auto-scaling current measurements. By switching in additional parallel resistances as needed, the device is capable of measuring current from microamps to amps through low-side shunts. 

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  • Automatic shunt switching

    • Comparators to detect burden voltage​

    • Latches to store current 'range' of measurement

    • Low-side FETs with FET drivers to quickly switch in parallel resistors

  • Mixed Analog/Digital Design​

    • Careful routing away from digital signals​

    • Instrumentation amplifier

    • 12-bit SAR ADC

  • Trim-pot configurable switching thresholds​

  • Testpoints for easy troubleshooting

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'Dext' Gesture-Based Input Device

College multi-disciplinary project to iterate on a gesture-based keyboard-equivalent input device. Worked with mechanical, software, computer, and biomedical engineers to create a functional prototype capable of typing with one hand.

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  • NRF52 in Arduino environment for BLE HID

  • Tactile switches in front of each finger (4)

  • Accelerometer to detect hand orientation (roll only)

  • With 3 hand orientations and 10 finger combinations, 30 characters were possible

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