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Overview

boards/realtek/rtl8721f_evb/doc/index.rst

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.. zephyr:board:: rtl8721f_evb

Overview

The Realtek RTL8721F Series is a low-power, single-chip microcontroller featuring dual RISC cores compatible with the Arm® Cortex®-M55 instruction set, designed for optimized power efficiency, RF performance, and ultra-low power consumption. It incorporates comprehensive low-power features such as fine-grained clock gating, multiple power modes, and dynamic power scaling. As a dual-band (2.4 GHz and 5 GHz) communication controller, the RTL8721F integrates Wi-Fi 6 (802.11a/b/g/n/ac/ax with 20 MHz bandwidth) and Bluetooth Core 5.4 Qualified specifications, combining a WLAN MAC, a 1T1R-capable WLAN baseband and RF, along with Bluetooth functionality to deliver complete wireless connectivity solutions. For more information, check RTL8721F-EVB_.

Hardware

The features of RTL8721F include the following:

  • Dual cores: two Real-M300 (or KM4 thereafter) processors

    • KM4TZ: KM4 with Arm TrustZone®-M security technology, usually works as Application Processor
    • KM4NS: KM4 without Arm TrustZone®-M security technology, usually works as Network Processor

  • 512KB on-chip SRAM

  • Wi-Fi 6 (802.11 a/b/g/n/ac/ax), 1T1R, 2.4GHz/5GHz dual-band

  • Bluetooth 5.0 LE

  • Peripheral Interface:

    • Flexible design of GPIO configuration
    • Multi-communication interfaces: SPI x 2, UART x 5, I2C x 2, I2C-like x 1
    • Hardware IR transceiver, easy to adapt to various IR protocols
    • Supports Real-Time Clock timer together with 4 basic timers
    • Supports 4 x 4 channels of PWM timer and 1 capture timer
    • Supports 2 group PMC timers
    • Supports a general 12-bit ADC: 8 external channels and 4 internal channels
    • Supports 9 channels of touch pad
    • Supports 8 independent channels of GDMA
    • Supports USB 2.0 High-speed in either Host or Device mode
    • Supports SDIO in both Host and Device modes, with options for 1-bit and 4-bit modes
    • Supports SD host controller to access SD card and eMMC device
    • Integrated Pixel Processing Engine (PPE) to process pixel data faster
    • LCDC
    • MJPEG hardware decoder to enhance HMI performance
    • A2C (compatible with ISO 11898-1, CAN Specification 2.0)
    • Ethernet MAC
    • Integrated audio codec supports 2 channels DMIC interface
    • I2S x 1: up to 384kHz sampling rate
    • Supports thermal detector to detect and monitor the real-time temperature inside the chip

  • Cryptographic hardware acceleration (TRNG, ECC/RSA, SHA-2, AES，Flash XIP decryption)

For more information, refer to the RTL8721F Application Note, the RTL8721F Datasheet, and the RTL8721F Pinmux Table_, depending on the chip you are using.

Supported Features

.. zephyr:board-supported-hw::

System Requirements

Binary Blobs

Realtek HAL requires binary blobs in order work. Run the command below to retrieve those files.

.. code-block:: console

west blobs fetch hal_realtek

.. note::

It is recommended running the command above after west update.

Programming and Debugging

.. zephyr:board-supported-runners::

Building

An example of building the :zephyr:code-sample:hello_world application is shown below:

.. zephyr-app-commands:: :zephyr-app: samples/hello_world :board: rtl8721f_evb :goals: build

Flashing

The standard flash target is supported by the board configuration.

Enter Download Mode

To flash the device, you must first put the SoC into download mode using the on-board FT232RL USB-to-UART converter. Follow these steps:

  1. USB Connection: Connect a USB cable to the USB2UART port.

  2. Enter Download Mode:

    • Press and hold the Download button.
    • While holding it, briefly press the Chip_En button to reset the SoC.
    • Release the Download button after the reset.

The SoC is now in download mode and ready to receive firmware.

.. note::

The <port_name> placeholder in the flash command must be replaced with the actual serial port (e.g., /dev/ttyUSB0 on Linux or COM3 on Windows).

An example for flashing the :zephyr:code-sample:hello_world application is shown below:

.. zephyr-app-commands:: :zephyr-app: samples/hello_world :board: rtl8721f_evb :goals: flash :flash-args: --port <port_name>

Enter Normal Mode

After flashing completes successfully, press the Chip_En button once to reboot the SoC. The device then boots into normal mode and executes the flashed Zephyr firmware.

Debugging

Debugging is supported via SWD using a J-Link debug probe connected to PA18 (SWD_CLK) and PA19 (SWD_DAT). An example debug command for the :zephyr:code-sample:hello_world application:

.. zephyr-app-commands:: :zephyr-app: samples/hello_world :board: rtl8721f_evb :maybe-skip-config: :goals: debug

References

.. target-notes::

.. _RTL8721F-EVB: https://aiot.realmcu.com/en/home.html .. _RTL8721F Application Note: https://aiot.realmcu.com/cn/latest/ .. _RTL8721F Datasheet: https://aiot.realmcu.com/en/datasheet/index.html .. _RTL8721F Pinmux Table: https://aiot.realmcu.com/en/pinmux/pinmux_table.html