Cypress Semiconductor / Mbed OS mbed-os-example-xip

This example demonstrates the Execute-In-Place (XIP) feature of PSoC 6 MCU using external serial memory.

PSoC 6 MCU External Flash Access in XIP Mode

This example demonstrates the Execute-In-Place (XIP) feature of PSoC® 6 MCU using the Serial Memory Interface (SMIF) peripheral. In this example, an application which blinks an LED is placed and executed from external QSPI memory. The user can change the LED blinking rate (1 Hz or 4 Hz) using the user button.

Tested with Mbed OS v6.2.1

Requirements

• Programming Language: C/C++
• Associated Parts: All PSoC® 6 MCU parts

• Mbed CLI

• ModusToolbox v2.1 or later

Note: You do not need to install ModusToolbox to build and run this code example. However, installing it is required when you need to:

• Debug using the Eclipse for ModusToolbox IDE. See the user guide for details.
• Customize the default device configuration using any of the Configurator tools
• Port this code example to a new target that is not listed under the Supported Kits

Supported Toolchains (Mbed CLI argument --toolchain)

• GNU Arm Embedded Compiler v9.2.1 (GCC_ARM)
• Arm compiler v6.14 (ARM)

Supported Kits (Mbed CLI argument --target)

• PSoC 6 Wi-Fi BT Prototyping Kit (CY8CPROTO-062-4343W)
• PSoC 6 WiFi-BT Pioneer Kit (CY8CKIT-062-WIFI-BT)
• PSoC 6 BLE Pioneer Kit (CY8CKIT-062-BLE)
• PSoC 62S2 Wi-Fi BT Pioneer Kit (CY8CKIT-062S2-43012)
• PSoC 62S1 Wi-Fi BT Pioneer Kit (CYW9P62S1-43438EVB-01)
• PSoC 62S1 Wi-Fi BT Pioneer Kit (CYW9P62S1-43012EVB-01)
• PSoC 62S3 Wi-Fi BT Prototyping Kit (CY8CPROTO-062S3-4343W)

Hardware Setup

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

Note: The PSoC 6 BLE Pioneer Kit (CY8CKIT-062-BLE) and the PSoC 6 WiFi-BT Pioneer Kit (CY8CKIT-062-WIFI-BT) ship with KitProg2 installed. The ModusToolbox software requires KitProg3. Before using this code example, make sure that the board is upgraded to KitProg3. The tool and instructions are available in the Firmware Loader GitHub repository. If you do not upgrade, you will see an error like “unable to find CMSIS-DAP device” or “KitProg firmware is out of date”.

For Mbed OS, the kit must be in DAPLink mode. Refer the KitProg3 User Guide (found in the Documentation tab in the Cypress Programming Solutions web page) for details of how to put the Pioneer Kit into DAPLINK mode.

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.

Import the Code Example using Mbed CLI Tool

Mbed CLI commands are used to import the code example and compile. See Working with Mbed CLI web page.

mbed import https://github.com/cypresssemiconductorco/mbed-os-example-xip

It first clones the code example repository from GitHub, and then deploys all the libraries. If you wish to perform the deploy process manually, follow the below commands:

Clone the GitHub code example repository:

git clone https://github.com/cypresssemiconductorco/mbed-os-example-xip && cd mbed-os-example-xip

Deploy the dependent libraries. The library files are identified with .lib extension.

mbed deploy

Set the current directory as root:

mbed new .

Operation

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

2. Program the board.

   mbed compile -m <TARGET> -t <TOOLCHAIN> --flash --sterm

   For instance, to build for the target CY8CPROTO_062_4343W with GCC_ARM toolchain, use the following command:

   mbed compile -m CY8CPROTO_062_4343W -t GCC_ARM --flash --sterm

Note: With the –sterm option, Mbed CLI opens a new terminal with 9600-8N1 as the setting after programming completes. Do not use this option if you want to connect using another serial terminal application such as PuTTY or Tera Term.

3. After programming, the application starts automatically. Confirm that user LED (LED1) is blinking at 1 Hz.

4. Press the user button (SW2) on the kit. The LED will start to blink more rapidly at 4 Hz.

5. Step 4 can be repeated any number of times to change the LED blink rate back and forth (1 Hz or 4 Hz).

Figure 1. Output in UART Terminal

Debugging

You can debug the example to step through the code. In the IDE, use the \ Debug (KitProg3_MiniProg4) configuration in the Quick Panel. For more details, see the “Program and Debug” section in the Eclipse IDE for ModusToolbox User Guide.

Follow the steps from Eclipse IDE for ModusToolbox User Guide to export the Mbed OS code example and import it into ModusToolbox IDE for programming and debugging.

Mbed OS also supports debugging using any IDE that supports GDB. We recommend the user to go through ARM Mbed’s documentation on the debugging steps.

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 - 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

This example demonstrates the Execute-In-Place (XIP) feature of PSoC 6 MCU
using the SMIF peripheral. In this example, an application which blinks an LED is placed and executed from external QSPI memory. The user can change the LED blnking rate (1 Hz or 4 Hz) using the user button.

The target board (see Supported Kits) has a QSPI based external flash memory. This example uses SMIF peripheral in XIP mode and Serial Flash library to execute program from the external QSPI based flash memory. The SMIF peripheral of PSoC 6 MCU is enabled in XIP mode by the Mbed OS initialization code mbed_sdk_init which is called before the main function executes. The code for XIP mode is enabled by defining the macros CY_ENABLE_XIP_PROGRAM and overriding the target configuration target.xip-enable to true. These are defined in the mbed_app.json file.

The functions in the source file xip_blinky_app.cpp - led_blink_external_memory, callback_lp_ticker and isr_user_button are placed in the cy_xip section of the memory by means of linker script instructions. The cy_xip section of the linker file is mapped to the external memory location starting at an address location 0x18000000 of the PSoC 6 MCU memory map.

In GCC Arm compiler, the object file xip_blinky_app.o is placed in cy_xip with the following linker instructions:

.cy_xip :
    {
        . = ALIGN(4);
        *xip_blinky_app.o (.text* ) 

    } > xip 

In Arm compiler this is achived by:

LR_EROM XIP_START XIP_SIZE
{
    .cy_xip XIP_START  XIP_SIZE
    {
        xip_blinky_app.o (.text*)
    }      
}

See the respective compiler linker scripts for more details.

Further, the macro CY_ENABLE_XIP_PROGRAM defined in the mbed_app.json file instructs the programming tool (DAPLink) to program the code placed in cy_xip section into the external memory.

Resources and Settings

The following resources are used in this example.

Table 1. Application Resources

Related Resources

Other Resources

Cypress provides a wealth of data at www.cypress.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 Cypress community.

Document History

Document Title: CE230998 - PSoC 6 MCU External Flash Access in XIP Mode

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