Circuit printer: A rapid prototyping machine for electrical circuits

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Another interesting micrcontroller-based design project done by Bruce Land‘s students at Cornell this fall is a circuit printer, a rapid prototyping machine that prints electrical circuits on a piece of paper. Designed by Connor Archard and Feiran Chen, this printer uses an electrically conductive ink pen to rapidly create circuits. The circuit to be printed is drawn through an Web-app and can be sent to the printer from anywhere in the local area network. As shown in the following demo video, the Web-app allows users to draw out circuits quickly, converts them into vectors and then send them out frame by frame

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Single digit Nixie clock driven by PIC16F84A

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This IN-18 Nixie tube clock project  utilizes the PIC16F84A microcontroller and displays hours and minutes on a single tube. The circuitry is simple and the author used salvaged parts from a disposable camera to construct the high voltage power supply required for the Nixie tube. The time is displayed in the single digit by periodically flashing the digits from tens of hours to minutes. A tact switch is also implemented to set the time. It has to be pushed when the digit you want to change is being displayed. The current display is increased by one each time the switch is pressed and

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Bluetooth controlled robot car

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Christine and Shela‘s final project for the ECE4760 (Digital Systems Design Using Microcontrollers) class they took this fall was a Bluetooth controlled car with a dedicated remote control device. The car and the remote both uses Atmega1248P microcontrollers and HC-05 Bluetooth transceiver modules. The remote also consists of a MPU-6050 gyroscope/accelerometer module on board to sense the tilting angle of the remote. Once the two Bluetooth units are paired, the remote control device continuously sends out the tilt angle data to the car. The Atmega1248P on board the car then linearly maps the tilt angles to the the duty cycles of the

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STM32 External Interrupt

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In my earlier post on STM32 GPIOs I showed how to flash a LED with variable delay times. That example was based on polling method where the code continuously monitored the logic state of a GPIO input pin attached to a push button to determine the delay amount. Obviously that won’t be an efficient technique when a program will be of a considerable size and complexity. This is simply so because the CPU will have to check the GPIO’s logic state every time the super-loop (while (1) loop in the main function) repeats and the push button will also not

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Real-time sound spectrography using Atmega1284

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A sound spectrogram is a visual representation of the frequency components contained in an audio signal. The device that generates the spectrogram is called spectrograph. In a spectrogram, the horizontal axis is time and the vertical axis represents frequency. The spectrogram is color coded or gray-scaled to represent the relative intensity of the sound in each frequency region and time. Some of the applications of spectrograms are speech analysis and enhancement, studying bird and animal calls, music formation, etc. During pre-computer era, the spectrograms were generated using analog techniques that involved a series of bandpass filters. With the advent of

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