PSoC™ 6 MCU: SAR ADC simultaneous sampling

This code example demonstrates simultaneous sampling of two SAR ADCs. This code example is supported on devices such as PSoC™ 62 MCU (CY8C62x4) which has two SAR ADCs.

The two SAR ADCs are configured to sample inputs simultaneously from pins P10.0 and P10.1. Data acquired from these pins is converted to equivalent voltage. The product of two input voltages is loaded onto the CTDAC, from which the output can be measured on pin P9.2. Because the output on the analog pins is limited to 3.3 V, the product of the output voltages are scaled to fit within this range. The voltage measured at the output pin P9.2 must be multiplied with 3.3 to obtain the actual result.

The input voltages are displayed on the UART.

View this README on GitHub.

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Requirements

• ModusToolbox™ software v3.0

• Board support package (BSP) minimum required version: 4.0.0

• Programming language: C

• Associated parts: All CY8C62x4 parts

Supported toolchains (make variable 'TOOLCHAIN')

• GNU Arm® embedded compiler v10.3.1.124 (GCC_ARM) - Default value of TOOLCHAIN
• Arm® compiler v6.16 (ARM)
• IAR C/C++ compiler v9.30.1 (IAR)

Supported kits (make variable 'TARGET')

• PSoC™ 62S4 pioneer kit (CY8CKIT-062S4) - Default value of TARGET

Hardware setup

This example uses the board's default configuration. See the kit user guide to ensure that the board is configured correctly.

Software setup

Install a terminal emulator if you don't have one. Instructions in this document use Tera Term.

This example requires no additional software or tools.

Using the code example

Create the project and open it using one of the following:

In Eclipse IDE for ModusToolbox™ software

1. Click the New Application link in the Quick Panel (or, use File > New > ModusToolbox™ Application). This launches the Project Creator tool.

2. Pick a kit supported by the code example from the list shown in the Project Creator - Choose Board Support Package (BSP) dialog.

   When you select a supported kit, the example is reconfigured automatically to work with the kit. To work with a different supported kit later, use the Library Manager to choose the BSP for the supported kit. You can use the Library Manager to select or update the BSP and firmware libraries used in this application. To access the Library Manager, click the link from the Quick Panel.

   You can also just start the application creation process again and select a different kit.

   If you want to use the application for a kit not listed here, you may need to update the source files. If the kit does not have the required resources, the application may not work.

3. In the Project Creator - Select Application dialog, choose the example by enabling the checkbox.

4. (Optional) Change the suggested New Application Name.

5. The Application(s) Root Path defaults to the Eclipse workspace which is usually the desired location for the application. If you want to store the application in a different location, you can change the Application(s) Root Path value. Applications that share libraries should be in the same root path.

6. Click Create to complete the application creation process.

For more details, see the Eclipse IDE for ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mt_ide_user_guide.pdf).

In command-line interface (CLI)

ModusToolbox™ software provides the Project Creator as both a GUI tool and the command line tool, "project-creator-cli". The CLI tool can be used to create applications from a CLI terminal or from within batch files or shell scripts. This tool is available in the {ModusToolbox™ software install directory}/tools_{version}/project-creator/ directory.

Use a CLI terminal to invoke the "project-creator-cli" tool. On Windows, use the command line "modus-shell" program provided in the ModusToolbox™ software installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ software tools. You can access it by typing modus-shell in the search box in the Windows menu. In Linux and macOS, you can use any terminal application.

The "project-creator-cli" tool has the following arguments:

Argument	Description	Required/optional
--board-id	Defined in the <id> field of the BSP manifest	Required
--app-id	Defined in the <id> field of the CE manifest	Required
--target-dir	Specify the directory in which the application is to be created if you prefer not to use the default current working directory	Optional
--user-app-name	Specify the name of the application if you prefer to have a name other than the example's default name	Optional

The following example clones the "mtb-example-psoc6-sar-adc-simultaneous-sampling" application with the desired name "Psoc6SarAdc" configured for the CY8CKIT-062S4 BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CKIT-062S4 --app-id mtb-example-psoc6-sar-adc-simultaneous-sampling --user-app-name Psoc6SarAdc --target-dir "C:/mtb_projects"

Note: The project-creator-cli tool uses the git clone and make getlibs commands to fetch the repository and import the required libraries. For more details, see the "Project creator tools" section of the ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

In third-party IDEs

Use one of the following options:

• Use the standalone Project Creator tool:

  1. Launch Project Creator from the Windows Start menu or from {ModusToolbox™ software install directory}/tools_{version}/project-creator/project-creator.exe.

  2. In the initial Choose Board Support Package screen, select the BSP, and click Next.

  3. In the Select Application screen, select the appropriate IDE from the Target IDE drop-down menu.

  4. Click Create and follow the instructions printed in the bottom pane to import or open the exported project in the respective IDE.

• Use command-line interface (CLI):

  1. Follow the instructions from the In command-line interface (CLI) section to create the application, and import the libraries using the make getlibs command.

  2. Export the application to a supported IDE using the make <ide> command.

  3. Follow the instructions displayed in the terminal to create or import the application as an IDE project.

For a list of supported IDEs and more details, see the "Exporting to IDEs" section of the ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

Operation

1. Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.

2. Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.

3. Program the board using one of the following:

   Using Eclipse IDE for ModusToolbox™ software

   1. Select the application project in the Project Explorer.

   2. In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4).

   Using CLI

   From the terminal, execute the make program command to build and program the application using the default toolchain to the default target. The default toolchain and target are specified in the application's Makefile but you can override those values manually:

   make program TARGET=<BSP> TOOLCHAIN=<toolchain>
   

   Example:

   make program TARGET=CY8CKIT-062S4 TOOLCHAIN=GCC_ARM
   

4. After programming, the application starts automatically. Ensure that input voltages are provided on analog input pins P10.0 and P10.1. Confirm that the input voltages are displayed on the UART terminal.

   Figure 1. Terminal output on program startup

   

5. Vary the input voltages and observe the change in SAR ADC readings. Measure the voltage product on analog output pin P9.2 and multiply the measured value with 3.3 to get actual result.

   Note: The voltage product value is scaled to fit within the allowed analog pin range of 0 V - 3.3 V. The CTDAC next value register can be set with a value from 0 to 4095, which translates linearly to the output pin voltage varying from 0 V to 3.3 V. The maximum product of two inputs can be 3.3 V x 3.3 V = 10.89 V. Because the physical pin voltage can vary from 0 V to 3.3 V and the actual voltage can vary from 0 to 10.89 V, the scaling factor is 3.3. That is, to determine the actual product voltage value, measure the voltage on pin P9.2 and multiply it by 3.3.

Debugging

You can debug the example to step through the code. In the IDE, use the <Application Name> Debug (KitProg3_MiniProg4) configuration in the Quick Panel. For details, see the "Program and debug" section in the Eclipse IDE for ModusToolbox™ software user guide.

Note: (Only while debugging) On the CM4 CPU, some code in main() may execute before the debugger halts at the beginning of main(). This means that some code executes twice - once before the debugger stops execution, and again after the debugger resets the program counter to the beginning of main(). See KBA231071 to learn about this and for the workaround.

Design and implementation

In this example, the two SAR ADCs (SAR0 and SAR1) are configured to sample the voltage from an I/O pin. The raw data acquired from the two pins is converted to an equivalent voltage, and are then multiplied together. The resultant product is scaled and then driven on the analog output pin P9.2 using a CTDAC. The input voltages are displayed on the UART.

In this example, a TCPWM is configured to trigger both the SAR ADCs periodically.

A CTDAC is configured in a buffered output configuration. The CTBm opamp is used as an output buffer in a voltage follower configuration.

The hardware configuration is done using the device configurator. The configuration is saved in a custom design.modus file in the application. In the firmware, the hardware is accessed using the peripheral driver library (PDL) rather than the higher-level hardware abstraction library (HAL). This is because the HAL provides several advanced features such as dual SAR ADC that is capable of simultaneous sampling and the deep sleep operation of the SAR ADCs (with the availability of the timer and the low-power oscillator) which are not available in other PSoC™ 6 MCU devices. This example uses these advanced features.

Figure 2. Flowchart

Resources and settings

This code example uses a custom configuration defined in the design.modus file located in <application_folder>/templates/TARGET_<BSP-NAME>/config/design.modus. There is a sub-folder for each board supported. The analog components used in this example are two SAR ADCs, one CTDAC, and one opamp. A TCPWM is also enabled in the device configurator for hardware triggering of the ADCs.

Figure 3. Device configurator

Simultaneous sampling requires that the simultaneous trigger option for SAR0 and SAR1 is enabled under the Programmable Analog selection, which is shown as follows:

Figure 4. Enabling simultaneous trigger for SAR0 and SAR1

For simultaneous sampling, both SAR ADCs (SAR0 and SAR1) must have the same settings. Because this example also supports hardware trigger, TCPWM0 is set as SOC input for the SAR ADCs. Because the SAR ADC has been configured as single-ended and VREF has been set as VDDA, the input voltage range on each analog input pin is 0 V - 3.3 V.

Figure 5. SAR0 and SAR1 configuration

The CTDAC is configured for buffered output. This requires the CTBm to be enabled and configured. The output from CTBm opamp is routed to pin P9.2, from which the scaled output voltage is to be measured. See Figure 6 for the settings that configure CTDAC for buffered output with CTBm as an opamp in a voltage follower configuration.

Figure 6. CTDAC configuration

Figure 7. CTBm configuration

In the TCPWM configuration (see Figure 8), the terminal count trigger is configured as the input to SAR0 and SAR1. The clock source to TCPWM is the peripheral clock (1 MHz). In the TCPWM configuration, the prescaler value is set to 1 and the period is set to 200000. Therefore, the TCPWM triggers every 200 ms (200000/1 MHz).

Figure 8. TCPWM configuration

Modifying the code example

1. This code example is designed with a very low SAR input trigger frequency for demonstration purpose to print the results on the UART. To achieve sampling at higher rates, decrease the period value in the TCPWM configuration and remove the printf statement.

2. Firmware trigger can also used to trigger the SAR ADCs by calling Cy_SAR_SimultStart.

Table 1. Application resources

Resource	Alias/object	Purpose
SAR (PDL)	SAR	SAR driver to measure input voltages
SYSANALOG (PDL)	PASS	SYSANALOG driver for AREF
CTB (PDL)	CTBM	Opamp for input buffer
CTDAC (PDL)	CTDAC	DAC driver to drive output to analog pins
UART (HAL)	cy_retarget_io_uart_obj	UART HAL object used by retarget-io for debug UART port

Related resources

Resources	Links
Application notes	AN228571 – Getting started with PSoC™ 6 MCU on ModusToolbox™ software AN215656 – PSoC™ 6 MCU: Dual-CPU system design
Code examples	Using ModusToolbox™ software on GitHub Using PSoC™ Creator
Device documentation	PSoC™ 6 MCU datasheets PSoC™ 6 technical reference manuals
Development kits	Select your kits from the evaluation board finder
Libraries on GitHub	mtb-pdl-cat1 – PSoC™ 6 peripheral driver library (PDL) mtb-hal-cat1 – Hardware abstraction layer (HAL) library retarget-io – Utility library to retarget STDIO messages to a UART port
Middleware on GitHub	capsense – CAPSENSE™ library and documents psoc6-middleware – Links to all PSoC™ 6 MCU middleware
Tools	Eclipse IDE for ModusToolbox™ software – ModusToolbox™ software is a collection of easy-to-use software and tools enabling rapid development with Infineon MCUs, covering applications from embedded sense and control to wireless and cloud-connected systems using AIROC™ Wi-Fi and Bluetooth® connectivity devices.

Other resources

Infineon provides a wealth of data at www.infineon.com to help you select the right device, and quickly and effectively integrate it into your design.

For PSoC™ 6 MCU devices, see How to design with PSoC™ 6 MCU - KBA223067 in the Infineon Developer community.

Document history

Document title: CE230701 - PSoC™ 6 MCU: SAR ADC simultaneous sampling

Version	Description of change
1.0.0	New code example
1.1.0	Updated to support v2.X CY8CKIT-062S4 BSP
1.2.0	Updated the design file to support ModusToolbox™ v2.3 and higher
2.0.0	Major update to support ModusToolbox™ v3.0. This version is not backward compatible with previous versions of ModusToolbox™

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