RTL8721F Evaluation Board

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 [1].

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 [2], the RTL8721F Datasheet [3], and the RTL8721F Pinmux Table [4], depending on the chip you are using.

Supported Features

The rtl8721f_evb board supports the hardware features listed below.

on-chip / on-board
Feature integrated in the SoC / present on the board.
2 / 2
Number of instances that are enabled / disabled.
Click on the label to see the first instance of this feature in the board/SoC DTS files.
vnd,foo
Compatible string for the Devicetree binding matching the feature.
Click on the link to view the binding documentation.

rtl8721f_evb/rtl8721f target

Type

Location

Description

Compatible

CPU

on-chip

ARM Cortex-M55 CPU1

arm,cortex-m55

Clock control

on-chip

Generic fixed-rate clock provider1

fixed-clock

GPIO & Headers

on-chip

Realtek Ameba GPIO controller3

realtek,ameba-gpio

Interrupt controller

on-chip

ARMv8.1-M NVIC (Nested Vectored Interrupt Controller)1

arm,v8.1m-nvic

MTD

on-chip

Flash node1

soc-nv-flash

on-board

Fixed partitions of a flash (or other non-volatile storage) memory1

fixed-partitions

Pin control

on-chip

Realtek Ameba pinctrl is a singleton node responsible for controlling pin function selection and pin properties1

realtek,ameba-pinctrl

Serial controller

on-chip

Ameba LOGUART1

realtek,ameba-loguart

SRAM

on-chip

Generic on-chip SRAM1

mmio-sram

Timer

on-chip

ARMv8.1-M System Tick1

arm,armv8.1m-systick

System Requirements

Binary Blobs

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

west blobs fetch hal_realtek

Note

It is recommended running the command above after west update.

Programming and Debugging

The rtl8721f_evb board supports the runners and associated west commands listed below.

flash debug debugserver reset attach rtt
amebaflash ✅ (default)
jlink ✅ ✅ (default) ✅ ✅ ✅ ✅

Building

An example of building the Hello World application is shown below:

# From the root of the zephyr repository
west build -b rtl8721f_evb samples/hello_world

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 Hello World application is shown below:

# From the root of the zephyr repository
west build -b rtl8721f_evb samples/hello_world
west flash --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 Hello World application:

# From the root of the zephyr repository
west build -b rtl8721f_evb samples/hello_world
west debug

References