XMC™ MCU: DMA ring buffer

This code example demonstrates how to receive data using DMA via a universal serial interface channel (USIC) and synchronize the processing with an OS task through a ring buffer.

For simplicity, the OS task is emulated inside this example with a SysTick timer interrupt.

Requirements

• ModusToolbox™ software v3.0
• SEGGER J-Link software
• Programming Language: C
• Associated parts: All XMC4000 MCU parts

Supported toolchains (make variable 'TOOLCHAIN')

• GNU Arm® embedded compiler v10.3.1 (GCC_ARM) - Default value of TOOLCHAIN
• Arm® compiler v6.16 (ARM)
• IAR C/C++ compiler v9.30.1 (IAR)

Supported kits (make variable 'TARGET')

• XMC4200 Platform2Go kit (KIT_XMC_PLT2GO_XMC4200)
• XMC4300 relax EtherCAT kit (KIT_XMC43_RELAX_ECAT_V1)
• XMC4400 Platform2Go kit (KIT_XMC_PLT2GO_XMC4400)
• XMC4500 relax kit (KIT_XMC45_RELAX_V1) - Default value of TARGET
• XMC4700 relax kit (KIT_XMC47_RELAX_V1)
• XMC4800 relax EtherCAT kit (KIT_XMC48_RELAX_ECAT_V1)

Hardware setup

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

Additionally, an USB-to-UART serial adapter is required to test the code example on the XMC4500 relax kit.

Software setup

Install a terminal emulator if you do not 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:

project-creator-cli --board-id KIT_XMC47_RELAX_V1 --app-id mtb-example-xmc-dma-ring-buffer --user-app-name DMARingBuffer --target-dir "C:/mtb_projects"

Operation

1. Connect the board to your PC using a micro-USB cable through the debug USB connector.

2. Open a terminal program and select the J-Link CDC UART COM port. Configure the terminal with baud rate of 115200, data bits of 8, stop bits of 1, and with parity and flow control set to none.

3. Program the board 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 (JLink).

4. After programming, the application starts automatically. Confirm that the welcome message ("DMA Ring Buffer example") is displayed on the UART terminal.

   Figure 1. DMA ring buffer example in terminal

   

5. Type inside the terminal.

6. Confirm that the text you type is echoed on the terminal.

Debugging

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

Design and implementation

The code consists of two parts as follows:

• Part 1: Defines and configures the DMA channel. The source address configured in the DMA is the 'RBUF' register (XMC_UART0_CH0->RBUF), where the data should be read from. The destination address is the address of the first element in the ring buffer array ring_buffer[0]. The data received via the UART and saved in the ring buffer is echoed to the UART. This task takes over the SysTick_Handler() interrupt function, which calls the uart_transmit() function to transmit the data from the ring buffer when new data is written by the DMA to the ring buffer.

• Part 2: Initializes and enables the DMA module in the main function using the configuration from Step 1. It also configures the system time using the SysTick_Config() function, which calls the SysTick_Handler() function every 1 ms.

Resources and settings

The project uses a custom design.modus file because the following settings were modified in the default design.modus file.

Figure 2. USIC channel

Related resources

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 XMC™ MCU devices, see 32-bit XMC™ industrial microcontroller based on Arm® Cortex®-M.

Document history

Document title: CE232572 – XMC™ MCU: DMA ring buffer

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