Fullscreen HTML5Med Res (??MB)HTML4

Introduction to Programming – Part 2 ˃Cypress’ System on a Chip Analog/digital signals and debugging Our last tutorial on using the Cypress Programmable System on a Chip covered programming and using these fascinating mixed analog/digital devices, but being an introductory article, didn’t go into great detail on how to use the programmable analog features which make them so unique. This followup article describes the more powerful CY8CKIT-059 board and explains how to use its capabilities. By Dennis Smith O ur previous article on using Cypress PSoCs (October 2018; siliconchip.com.au/Article/11269) introduced the Cypress Semiconductor CY8CKIT-049-42XX development code, a 32-bit ARM development platform. We described how to install and use its integrated development environment (IDE), and provided a sample program to read the temperature from an NTC thermistor and display it on an LCD screen. This article is based on the more powerful CY8CKIT-059 board, with attached Serial Wire Debug adaptor (SWD) and programmer, shown above. Incidentally, the included SWD adaptor and programmer can also be used with the 049-42XX boards. The main product page for the CY8CKIT-059-5LP development board, which contains links to extensive documentation and the relevant downloads, is at: siliconchip.com.au/link/ aaqn You may need to create a free Cypress account to download the files. The development board is available in Australia for just over $20 (at the time of writing) from element14, Mouser, RS Australia etc. The integrated development environment (IDE), called PSoC Creator, complete with compiler and device specific libraries is available to download for free from the product page above. The CY8CKIT-059-5LP board is 92 Silicon Chip designed around the CY8C5888LTILP097 chip (see www.cypress.com/ part/cy8c5888lti-lp097) which is available in 68-pin QFN or 100-pin TQFP packages (both surface-mounting). It contains an ARM Cortex-M3 32-bit CPU running at up to 80MHz, 256KB of flash memory and 64KB of SRAM; which makes it quite powerful as microcontrollers go. You can download the chip’s Product Overview document, which lists all of its important features, at: www. cypress.com/file/140796/ The chip also includes a coprocessor, called the Digital Filter Block (DFB), which is a 24-bit digital signal processor (DSP). A datasheet on this co-processor can be found at: www. cypress.com/file/315811/ The DFB is useful for certain tasks like matrix/vector multiplication or analog signal processing. Performing these jobs using the DFB frees up the main CPU for other tasks. It also includes programmable analog and digital components, such as ADCs, DACs, timers/PWM inputs, serial communication etc. CY8CKIT-059 Features 32-bit ARM microcontroller with 256KB flash and 64KB SRAM 24-channel direct memory access (DMA) controller Capacitive touch sensing Programmable analog blocks, including: • one 8- to 20-bit delta-sigma analog-to-digital converter (ADC) • two 12-bit successive approximation (SAR) ADCs • analog multiplexers, which can make the ADCs multi-channel capable • four 8-bit DACs • four comparators • four op amps • four programmable analog blocks (continuous time or switched capacitor) Programmable digital blocks: • four timers/counters/PWM (pulse width modulators) • 24 universal digital blocks (UDB), which include registers and an arithmetic logic unit (ALU) • Up to 72 input/output pins • On-chip JTAG/debugging • 1.2(1.7)-5.5V supply voltage Australia’s electronics magazine siliconchip.com.au A removable USB-to-serial and Serial Wire Debug adaptor is included in the kit. Once you have finished your project, the adapter can be snapped off and used as a general-purpose USB/ serial adaptor or as a Serial Wire Debug adaptor for any of the PSoC family boards. The adaptor can also be used as a USB to general-purpose I/O (GPIO) device. Becoming adept at programming PSoCs As with other micros, there’s a bit of a learning curve. The curve might be somewhat steeper with a PSoC than, say, an Arduino, but its ultimate capabilities are far greater. It has a 32-bit CPU rather than 8-bit, and much more memory, but is actually cheaper than most Arduino modules. Most importantly and uniquely, though, it has the configurable analog blocks which give you far greater flexibility and power when it comes to signal processing. Probably the biggest disadvantage of the PSoC compared to other 8-bit and 32-bit micros is that its extra capabilities translate into somewhat higher power requirements. You are also effectively stuck using the Creator IDE for programming PSoC boards; while it's possible to build the project yourself, it's impractical. It's important to note that since the community is smaller, fewer libraries are available for these devices compared to Arduino. Although, given the dodginess of some of the Arduino libraries we’ve come across, sometimes having to write your own code may be a blessing in disguise… to your “C:\Users\<USERNAME>\ Documents\PSoC Creator” folder. They can be placed in other folders if you want, but for this article, we’ll assume you’ve used this default location. Now plug the board into a USB 2.0 port on your PC. An orange LED on the USB-to-serial adaptor indicates that power is present, while a flashing blue LED indicates that all is well. Now unplug the board and plug it back in again, but this time, holding down the button at the rear of the board while you plug in. The blue light should now flash at a faster rate, indicating that the board is now in bootloader mode. With the 049-42XX board described in the previous article, the bootloader was the only way to load programs into the chip. This method still works with the CY8CKIT-059 board, but with this board, you can load your program straight into the board without having to enter bootloader mode. Preparing our first example We’ve provided two example projects this time, both included in the free download (ZIP package) on the Silicon Chip website. We’ll start with the “AnalogDebugExample” project first. Navigate to the “AnalogDebugExample.cydsn” folder and double click on “AnalogDebugExample.cyprj”. This will open PSoC Creator 4.2 IDE and load the project files automatically. Otherwise, you can open the IDE, click “Open Existing Project” from the Start page and navigate to the project folder. You should now see the block diagram shown in Fig.1. If it is not visible, double click on the “TopDesign. cysch” tab at the top of the left panel. Now click on the “Connections” tab at the bottom, and you should see the wiring diagram shown in Fig.2. This just provides a guide for how to configure the hardware and is not required when you make your own projects. You can also view what pins are actively being used on the main IC by going to the Pins item under Design Wide Resources in the left sidebar of the IDE. You should see the same diagram shown in Fig.3. Connect two pushbutton switches to your board, as Fig.2. You can wire the components directly to the board, or if you solder header strips to the development board, you can plug it into a breadboard and then connect the switches that way. But if you are planning to snap off the USB-to-serial adaptor board later, don’t solder terminal strips on just yet. Building and uploading To build the project before programming the hardware, click on the build icon in the tools bar just above the Workspace Explorer window (you can also just press CTRL+F5). If all is well, Using PSoC Creator If you need a refresher on using the software, refer to the previous article (October 2018) on how to get started with Cypress PSoC, including downloading and installing the PSoC Creator IDE. Note that the IDE only supports Windows PCs (7-10). If you already have the IDE installed, you only need to download the “CY8CKIT-059 Kit Only” file from: siliconchip.com.au/link/aaqn Otherwise, you can download the “CY8CKIT-059 Kit Setup” file below it, which gives you the above files as well as the IDE. With the IDE installed, download the project files for this article fromsiliconchip.com.au and unzip the files siliconchip.com.au Fig.1: block diagram of the first example program as shown in PSoC Creator. This program uses an Arbitrary Waveform Generator (WaveDAC8) to generate a tune that is played by pressing SW_1, and have its pitch/tempo varied via SW_2. Australia’s electronics magazine September 2019  93 Fig.2: wiring diagram for the first example program. Note the circuit diagram and the breadboard layout which show how to connect an LM380 audio amplifier and speaker to the CY8CKIT-059 board. you will see output similar to the text below in the Output Window: ------- Build Started: 06/18/2018 14:06:49 Project: AnalogDebug, Configuration: ARM GCC 5.4-2016-q2-update Debug ------Flash used: 6086 of 262144 bytes (2.3%). SRAM used: 2849 of 65536 bytes (4.3%). Stack: 2048 bytes. Heap: 128 bytes. ------- Build Succeeded: 06/18/2018 14:07:18 ------- Fig.3: the active pins of the main IC used in the “Analog Debug” example program. You can view this by clicking on the “Pins” item under “Design Wide Resources” in the left sidebar of the IDE. 94 Silicon Chip Australia’s electronics magazine If you get an error message in the Output Window about missing binaries for the ARM GCC and MDK toolchain, this is because the project is set for a ‘debug’ build and the default toolchain in the build settings is incorrect. To fix this, go to Project → Build Settings in the toolbar. In the Build Settings sub-menu, the second entry “Toolchain” should be set to “ARM GCC 5.4-2016-q2-update” or similar instead of the default “ARM MDK Generic”. Or it might be due to not having the correct binaries for the 059 board. Just having the 042 kit files from the previous article is not enough to successfully build this project. siliconchip.com.au After this, the project should build without any errors, but you might get two warnings about asynchronous paths which you can safely ignore. Unlike the PSoC 049-42XX boards, it is not necessary to press a button on the board before programming. If programming is successful, the log will show a message similar to the one below: Fig.4: a breakpoint (indicated in red) can be set by either clicking to the left of the line-number, or right-clicking the line and selecting “Insert Breakpoint”. Breakpoints determine when to temporarily stop code execution during debugging. ------- Rebuild Succeeded: 06/22/2018 12:45:59 ------Programming device 'PSoC 5LP CY8C5888LT*-LP097' with file 'K:\ARM Development\ Cypress PSoC\Active Projects\ AnalogDebugExample\ AnalogDebug.cydsn\CortexM3\ ARM_MDK_Generic\Debug\ AnalogDebug.hex'. Device ID Check Erasing... Programming of Flash Starting... Protecting... Verify Checksum... Finished Programming Device ‘PSoC 5LP CY8C5888LT*LP097’ was successfully programmed at 06/22/2018 12:46:09. If the chip is programmed successfully, and you have a suitable audio amplifier connected, the opening theme from “The Godfather” will play each time you press SW_1. Pressing SW_2 changes the pitch and tempo while playing a piano scale. The music is created using the built-in arbitrary waveform generator (discussed later). Interactive debugging One of the problems with many microcontroller development systems, including the popular Arduino environment, is that they don’t give you an easy way to debug your program. What do you do if you write some code, upload it to the board, and it doesn’t do what you expected? You generally end up having to add lots of print statements throughout your code, so you can watch the serial console to find out what’s going wrong. That can be time consuming. Wouldn’t it be handy if you could step through each line of your code and check the value returned by a function or from a calculation, while also being able to see the value of each currently active variable? While this is theoretically possible with an Arduino, it is not easy to orsiliconchip.com.au Connection diagram for the PSoC CY8CKIT-059 board. Source and prototyping guide: www.cypress.com/file/157971/download Australia’s electronics magazine September 2019  95 Fig.5: when debugging, the current point of execution is indicated in yellow. If you click the tab at the bottom left called “Locals”, you should be shown the current values of all variables that are currently ‘in scope’. You can also set a “Watchpoint” via right-clicking the variable, which means that the value of that variable will always be displayed when ‘visible’. ganise. But PSoC Creator has in-built debugging. It does this via the 0595LP’s USB-to-serial adaptor which contains its own 32-bit ARM processor. It receives commands from the IDE and communicates with the 059-5LP’s (or 049-42XX) CPU to execute code one line at a time. Since the IDE has access to the source code of your program (including all the library code written by Cypress and others), it is possible to step through each line of code with a press of a key. Using the example project, we can step through the code and see what is happening at each point. It helps to tell the IDE how far through the program we want to go before debugging should start. To do this, we set a ‘breakpoint’. Fig.4 shows what the IDE looks like when we set a breakpoint at the first statement in the code, as indicated by the red blob to the left of the “CyGlobalIntEnable” statement. To set a breakpoint, click in the shaded vertical area to the left of line numbering, or right-click the line you 96 Silicon Chip want to break at, and select “Insert Breakpoint”. Click again on the red circle to remove the breakpoint. Breakpoints can be set on any line. Once you have a breakpoint set, click on the “Debug” drop-down menu and select “debug” or press F5. The IDE will compile the code and program the 059-5LP. It will then begin execution of the code and stop at the first breakpoint it detects. The yellow highlighting shown in Fig.5 indicates where the program execution is currently up to. Now when you click on the Debug drop-down menu, you will see some additional menu items. The new menu items show which function keys you can use to step through the code; for example, F10 will execute the current statement and then step to the next one, F11 is similar but will step into the function itself when relevant. Try pressing F10, then F11 while the “DAC_Start();” statement is highlighted. This will move the debugger to inside the scope of that function which is located in the file DAC.c. Australia’s electronics magazine So if you want to find out what happens within a function that’s called on the currently highlighted line, press F11. If you are only interested in what the function returns, press F10. To see the value of a variable (eg, Button_1_Pressed), hover the mouse cursor over that variable and a popup window will display details of the variable and its contents. Note, however, that the variable must be ‘in scope’, that is, local (or ‘visible’) to the function currently being executed. By right-clicking on the variable, a popup window appears that allows a “Watchpoint” to be created, which means that the IDE will always show the value of that variable whenever it is in-scope. Arbitrary Waveform Generation (WaveDAC8) The above example program uses the Arbitrary Waveform Generator (WaveDAC8) component to play music. This component has an analog output which can provide sine, square, triangle and sawtooth waveforms. It siliconchip.com.au also has the facility for the user to draw their own waveform. You can double-click on the WaveDAC8 component to change its parameters and hear the difference; for example, you can change the waveform shape, and that will affect the timbre of the sound it produces. The test waveforms are shown in Fig.6. Once you’ve wired up the circuit as described earlier, and programmed the chip, pressing pushbutton SW_1 plays a theme song, while pressing SW_2 plays a musical scale, first with the “DAC” object, then in reverse with “DAC_1”, which are both WaveDAC8 components. This demonstrates the use of different waveforms, but the second DAC could also be used for multi-channel playback. The “Voice_Write()” function modifies the contents of a CPU register which enables one DAC while disabling the other. To play the music, I’ve created an array of values which represent the frequency of each note in the tune. These are passed (one at a time) to the “PlayNote()” function, which alters the clock frequency driving each WaveDAC8 unit, to produce a different output frequency. The values stored approximate the frequencies of the notes on a piano. To create a different song, make a new array using TheGodFather[] as a template and following the comments in the code. There are ways to turn audio files, like mp3s, into arrays of bytes which can then be used with this program. Of course, you wouldn’t easily be able to fit more than snippets into program memory. By duplicating the “Volume” control component (a Programmable Gain Amplifier) and the output potentio- Fig.7: The “Analog_Alarm” program alters the behaviour of an LED depending on the input voltage from PIN_1 using the chip’s in-built configure hardware. meter, you can turn this project into a stereo synthesiser. With a little extra programming you could also control the gain of the PGA(s) with the software to set the volume. A second example If you wish to learn more about the Analog components built into the Cypress CY8CKIT-059-5LP, here is a second sample project. It is called “Analog_Alarm” and is included in the download package for this article. Open it up in the IDE, as you did with the previous project. You can see the block diagram for this program in Fig.7. It uses two 8-bit voltage DACs, a voltage reference, three analog comparators, an XOR gate, a 4-input analog multiplexer, a lookup table and three PWM units to produce a voltage alarm. The input voltage comes from the wiper of a potentiometer (variable resistor) connected to input port P3[0]. Depending on the position of the potentiometer, it will drive the onboard LED as follows: 1. For any voltage below 1V, the onboard LED is off. 2. Between 1-2V, the LED pulsates. 3. Between 2-4V, the LED flashes at 100Hz. 4. Above 4V, the LED remains continuously lit. These voltage ranges can easily be changed in the code. You can replace the potentiometer with a voltage source (0-5V only), and you have a voltage monitor facility. More example projects Cypress code Examples: siliconchip. com.au/link/aarf 100 Projects in 100 Days: siliconchip. com.au/link/aarg CY8CKIT-059 driving a VGA monitor: siliconchip.com.au/link/aarh Open FPGA tools: github.com/ azonenberg/openfpga CNC wood router using a 059-5LP: github.com/holla2040/hyatt Cypress buyout Fig.6: the two waveforms used for DAC (left) and DAC_1 (right) shown in Fig.1. siliconchip.com.au Australia’s electronics magazine Recently Cypress Semiconductors was acquired by Infineon for approximately €9B. The acquisition seems to be primarily for Cypress’ automotive electronics, but their microcontrollers like the CY8CKIT-059 shown in this article are likely to continue being developed and sold. SC September 2019  97