Category Archives for Projects

Bluetooth Low Energy Remote Control

Bluetooth is a protocol where a Master communicates with one or more Slaves; the Slaves cannot talk to each other. The Master is often a smartphone or computer, but this isn’t always desirable. A Bluetooth Master module will work very … Continue reading

13. February 2019 by sam
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FPGA-DSP Board for Narrowband SDR

When the push-to-talk (PTT) signal on header K7 is pulled logic Low (see Part 1, Figure 2), the FPGA goes into transmit mode. A CW carrier can then be generated with the DDS block in the FPGA, through the DAC, … Continue reading

07. February 2019 by sam
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GoNotify, a Flexible IoT Sensor Interface

Some time ago I wondered what the requirements for a connected device would be. First off, it had to be wireless, meaning it’s battery- or solar-powered. This in turn implies that it should consume as little energy as possible; hence … Continue reading

04. February 2019 by sam
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Filtered PWM

Figure 1 shows the spectrum of an unfiltered PWM signal with a basic frequency of 5 kHz and a duty cycle of 25%. As you can see, the harmonics at multiples of the basic frequency gradually fall off in amplitude … Continue reading

15. November 2018 by sam
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PWM Motor Control

The basic principle will be familiar to many readers: VDC is a DC voltage (DC for direct current, not to be confused with DC for Duty Cycle [2]). At switch-on the positive opamp input Vi is always greater than zero, … Continue reading

12. July 2018 by sam
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Truly Random-Number Generator

Because noise is random by nature, a noise source forms the basis of the RNG. The randomness of different types of electronic noise (shot, thermal, flicker, popcorn, avalanche, etc.) are well known. My RNG uses avalanche noise — which can … Continue reading

12. July 2018 by sam
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Swiss Pi Extensions – Servo Motor Extension

With the servo motor extension board (Figure 7) you can connect more servo motors to the Swiss Pi than the four supported directly. With two of these boards you can control a maximum of sixteen servo motors. The resistors protect … Continue reading

12. July 2018 by sam
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Swiss Pi Extensions – MOSFET Board

The MOSFET board (Figure 6) can be used to switch DC loads. The normal GPIO lines of the Swiss Pi or the PWM channels can be used for this purpose. Driving RGB LED strips is a typical application. For the … Continue reading

12. July 2018 by sam
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Swiss Pi Extensions – PWM to Voltage Converter

The PWM to 0–10 V converter board is intended to drive light dimmers (including LED dimmers), most of which use 0–10 V control signals. The PWM signal from the Swiss Pi is converted to a DC voltage by a RC … Continue reading

12. July 2018 by sam
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Swiss Pi Extensions – Current Loop Interface

Current loop interfaces are still widely used in the industrial sector for reading sensors, despite the advent of digital alternatives. Current loops are simple and robust, and they have a long working range. Consequently, there are a lot of sensors … Continue reading

12. July 2018 by sam
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