The LabRat:  Simplify PSoC Programming

The PSoC 3 First Touch Starter Kit gives users opportunities to learn more about the Cypress programmable embedded system-on-chip, or PSoC. The PSoC 3 family provides a wide array of internal capabilities and peripheral devices. But unlike most microcontrollers (MCUs), the PSoC devices rely on internal programmable logic that can place and route devices such as counters, timers, DMA channels and ADCs. Some functions, such as 4- and 8-bit counters, already exist within a PSoC chip. The PSoC Creator tools create others as needed and implements them in Universal Digital Blocks (UDBs) of programmable logic. A single-cycle 8051 core (67 MHz) provides the PSoC processor core.

You can find the data sheet for the CY8C3866AXI-040ES2 chip used on the board here. To me, the success of the hardware depends greatly on the innovative PSoC Creator software that simplifies system design and programming. Click here for information, video tutorials and data sheets for the PSoC 3 family.

I enjoyed working with this kit and except for the lack of a workbook or reference manual for the PSoC Creator tools, it rates highly.  I gave it a "4" rating for Meets Expectations only because the kit lacks do-it-yourself projects or follow-on exercises. If you want to concentrate on solving problems rather than becoming enmeshed in the details of complicated functions and I/O ports, I highly recommend the PSoC chips and the PSoC Creator software.
Support for the Micrium uC/OS II and the Segger embOS should become active soon for the higher-end PSoC 5 family of devices that include an 80-MHz ARM Cortex-M3 CPU rather than an 8051.

In addition to the PSoC chip, the board includes a CapSense touch-sensor slider, a proximity sensor, eight LEDs, a thermistor, an accelerometer, a USB interface and a push-button. The board communicates directly with a host PC through a standard USB cable. The board can run from a 9-V battery or from power through the USB cable. (Disconnect the battery after you use the board as a stand-alone device.)

Instructions on a one-page Quick Start Guide show how to connect the board to the 9-V battery and rapidly wave the board back and forth to display a "rasterized" message — PSoC Rocks! —  in the air as the LEDs turn on and off in response to the board's accelerometer signal. After I tested the board, I printed the "PSoC 3 First Touch Starter Kit Guide" provided on the CD, and followed the steps to load the PSoC Creator and PSoC Programmer software, and four sample projects. The first project opens the PSoC Rocks! project folders and lets users easily change any of the six messages the board will display and the duration of each message. At first I couldn't find the kit files, but only because my lab PC had not completed installing them on my Windows XP lab computer. Be patient when installing the software tools.

The PSoC Rocks! project worked as expected, and my modified message displayed "Lab Rat!" The Starter Kit Guide includes three other projects, a bubble-level emulator, a proximity sensor, and a CapSense slider control. I skipped them because I wanted to learn how to use the PSoC Creator software and make up my own experiment.

The PSoC Creator software includes a schematic-capture-like screen that lets developers select functional analog and digital building blocks such as timers, ports, clocks, UARTs, analog multiplexers, ADCs, DACs, and so on and move them into a TopDesign window. By using these blocks you avoid writing low-level code to control devices and I/O ports. The LED-display project, for example, contains three block; read the accelerometer's Y-axis voltage, set up the accelerometer and output the 8-bit LED values. The LED-output section uses graphical "wires" to connect an LED-control port to a set of inverters and then to two ports of four LEDs each.

When I double clicked on a component, PSoC Creator opened a configuration window that let me set start-up and operating conditions. Each configuration window also links to a data sheet that explained a component's operation, its input and output signals, configuration information, the application program interfaces (APIs), how the APIs operate, and sample code.

I chose to create an 8-bit binary counter that would display its count on the eight LEDs. But I couldn't figure out how to relate the building-block schematic diagram with the code to do something useful. An application person at Cypress suggested I watch the video:  "101 Introduction to the Architecture" that included a simple experiment that toggles an LED on or off based on an internal time delay. That video helped and its associated project operated properly. But I still needed a hand with an 8-bit counter. To view the video and three others, click here.

Cypress doesn't yet have step-by-step tutorials that explain how to do things with the PSoC Creator software and for that reason I rated the kit's documentation a "3." The examples in the Starter Kit Guide only have users duplicate steps rather than solve given problems, with answers provided later.

So, I talked with a member of the PSoC Creator team at Cypress and he walked me through a four-bit counter example. Based on his explanations, I quickly extended the design to an eight-bit counter that evening. My online version of this review includes or points to a tutorial that explains the steps I used to create the 8-bit counter. You can use that explanation as a do-it-yourself experiment that links hardware and software. My compiled programs flowed to the target PSoC chip through the USB cable and I used debug functions to monitor chip and program actions. It felt good to see the eight LEDs flash as expected for a binary counter.

Developing an application still requires writing C code. The schematic approach eliminates difficulties working with chip-level functions and devices, but the overall operation still depends on your C code. You can see that aspect of a design in my 8-bit counter example that required only eight lines of code to control an interrupt-driven program.

This kit and the PSoC creator have a lot of potential because they create a code "outline" based on the PSoC functional building blocks you use in a design and thus remove developers from the nitty-gritty details of register controls for I/O ports, configuring a 12-bit ADC, and so on. Schematic-diagram-like "wires" make connections as needed between these blocks through Universal Digital Blocks (UDBs). The PSoC Creator tools automatically use the UDBs to create any needed functions, such as 32-bit counters, and route signals between existing resources and I/O pins. Imagine having to write the code for a CAN-bus controller vs. dragging a CAN-bus controller into a schematic and using several configuration screens and prebuilt API functions. The latter approach wins every time.
I enjoyed working with this kit and except for the lack of a workbook or reference manual for the PSoC Creator tools, rate it highly. Perhaps Cypress will have that type of information available soon.

If you want to concentrate on solving problems rather than becoming enmeshed in the details of complicated functions and I/O ports, I highly recommend the PSoC chips and the PSoC Creator software.  Support for the Micrium uC/OS II and the Segger embOS should become active soon for the PSoC 5 family of devices that include an 80-MHz ARM Cortex-M3 CPU rather than an 8051.

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