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Programmable System on a Chip

Almost all investigations ultimately rely on electronic instrumentation in order to collect, massage and transmit the data to a computer. However, we prefer that these not be black boxes, but rather that students know how to build instruments to collect data in a variety of ways. In this workshop, we will use a Programmable System on a Chip (PSoC) development kit from Cypress Semiconductor Corporation to build a variety of electronic instruments. This device is the focus of our electronic instrumentation class and is also used throughout our curriculum in our advanced laboratory class, and as part of student research.

The PSoC is a mixed signal processor. It has a 32bit ARM processor (like most smart phones). What makes this device truly unique and useful for the physics laboratory is the inclusion of programmable analog capabilities (two op-amps, programmable gain amplifiers, three analog to digital converters [1-20 bit, 2-12 bit], analog multiplexers, digital to analog converters, frequency mixer, comparators, and sample and hold elements) and 24 Universal Digital Blocks (UDB’s). The UDB’s are “FPGA-like” in that they can be programmed for a variety of digital devices from discrete logic gates up to counters, timers, pulse width modulators, etc. Finally, there are two digital filter blocks which are helpful for signal processing.

We will explore interfacing to analog and digital sensors to perform a variety of measurements. These sensors will include thermal sensors, photodiodes, accelerometers, 1-D image arrays, radiation sensors, and thermocouple vacuum gauges. We will go over I2C, SPI, and USB communication for sensor to PC data transmission.

In the workshop, attendees will develop a variety of electronic instruments. Then the instruments will be used to perform an investigation. Sample instruments will include:

  1. A coincidence counter and pulse interval measurement which will be used with a simple LED based Single Photon Avalanche Photodiode, and for radiation counting.
  2. A multichannel voltmeter with ramp generator which will be used to determine Planck’s constant using an LED.
  3. Construction of a spectrograph using the PSoC to read a linear photodiode array and analyze the spectrum.
  4. Interface to thermal sensors to perform several thermodynamic investigations.
  5. Lock-in Amplifier

Tentative Schedule
Day 1: Introduction to PSoC hardware capabilities and software. Overview of our current use of PSoC and successes with students. Diving in with simple programming tasks to familiarize with the software and programmer. Create functional volt-ammeter for introduction to external interfacing.

Day 2: Linear detector array and spectroscopy. Build a lock-in amplifier.

Day 3: Digital logic—Pulse Width modulators, Counters, Building a counter for the SPADs. LED as a SPAD experiments.

Attendees should bring their own laptop and a micro-usb cable. A notebook will also be helpful.

Costs: Cy8cKit-059—PSoC 5 prototyping kit, $10; LCD screen, $10; Breadboard, $30; and assorted sensors, $20-$70.